diff --git a/stepper_motion/Makefile b/stepper_motion/Makefile
new file mode 100644
index 0000000..632b018
--- /dev/null
+++ b/stepper_motion/Makefile
@@ -0,0 +1,133 @@
+BINARY		= usb_cdc_simple
+BOOTPORT	?= /dev/ttyUSB0
+BOOTSPEED	?= 115200
+# change this linking script depending on particular MCU model,
+# for example, if you have STM32F103VBT6, you should write:
+LDSCRIPT	= ld/stm32f103x8.ld
+LIBNAME		= opencm3_stm32f1
+DEFS		= -DSTM32F1 -DEBUG
+
+OBJDIR = mk
+INDEPENDENT_HEADERS=
+
+FP_FLAGS	?= -msoft-float
+ARCH_FLAGS	= -mthumb -mcpu=cortex-m3 $(FP_FLAGS) -mfix-cortex-m3-ldrd
+
+###############################################################################
+# Executables
+PREFIX		?= arm-none-eabi
+
+RM			:= rm -f
+RMDIR		:= rmdir
+CC			:= $(PREFIX)-gcc
+LD			:= $(PREFIX)-gcc
+AR			:= $(PREFIX)-ar
+AS			:= $(PREFIX)-as
+OBJCOPY		:= $(PREFIX)-objcopy
+OBJDUMP		:= $(PREFIX)-objdump
+GDB			:= $(PREFIX)-gdb
+STFLASH		= $(shell which st-flash)
+STBOOT		= $(shell which stm32flash)
+
+###############################################################################
+# Source files
+LDSCRIPT	?= $(BINARY).ld
+SRC			= $(wildcard *.c)
+OBJS		= $(addprefix $(OBJDIR)/, $(SRC:%.c=%.o))
+
+ifeq ($(strip $(OPENCM3_DIR)),)
+OPENCM3_DIR := /usr/local/arm-none-eabi
+$(info Using $(OPENCM3_DIR) path to library)
+endif
+
+INCLUDE_DIR	= $(OPENCM3_DIR)/include
+LIB_DIR		= $(OPENCM3_DIR)/lib
+SCRIPT_DIR	= $(OPENCM3_DIR)/scripts
+
+###############################################################################
+# C flags
+CFLAGS		+= -Os -g
+CFLAGS		+= -Wall -Wextra -Wshadow -Wimplicit-function-declaration
+CFLAGS		+= -Wredundant-decls
+# -Wmissing-prototypes -Wstrict-prototypes
+CFLAGS		+= -fno-common -ffunction-sections -fdata-sections
+
+###############################################################################
+# C & C++ preprocessor common flags
+CPPFLAGS	+= -MD
+CPPFLAGS	+= -Wall -Werror
+CPPFLAGS	+= -I$(INCLUDE_DIR) $(DEFS)
+
+###############################################################################
+# Linker flags
+LDFLAGS		+= --static -nostartfiles
+LDFLAGS		+= -L$(LIB_DIR)
+LDFLAGS		+= -T$(LDSCRIPT)
+LDFLAGS		+= -Wl,-Map=$(*).map
+LDFLAGS		+= -Wl,--gc-sections
+
+###############################################################################
+# Used libraries
+LDLIBS		+= -l$(LIBNAME)
+LDLIBS		+= -Wl,--start-group -lc -lgcc -Wl,--end-group
+
+.SUFFIXES: .elf .bin .hex .srec .list .map .images
+.SECONDEXPANSION:
+.SECONDARY:
+
+ELF		:= $(OBJDIR)/$(BINARY).elf
+LIST	:= $(OBJDIR)/$(BINARY).list
+BIN		:= $(BINARY).bin
+HEX		:= $(BINARY).hex
+
+all: bin
+
+elf: $(ELF)
+bin: $(BIN)
+hex: $(HEX)
+list: $(LIST)
+
+$(OBJDIR):
+	mkdir $(OBJDIR)
+
+$(OBJDIR)/%.o: %.c
+	@printf "  CC      $<\n"
+	$(CC) $(CFLAGS) $(CPPFLAGS) $(ARCH_FLAGS) -o $@ -c $<
+
+$(SRC) : %.c : %.h $(INDEPENDENT_HEADERS)
+	@touch $@
+
+%.h: ;
+
+$(BIN): $(ELF)
+	@printf "  OBJCOPY $(BIN)\n"
+	$(OBJCOPY) -Obinary $(ELF) $(BIN)
+
+$(HEX): $(ELF)
+	@printf "  OBJCOPY $(HEX)\n"
+	$(OBJCOPY) -Oihex $(ELF) $(HEX)
+
+$(LIST): $(ELF)
+	@printf "  OBJDUMP $(LIST)\n"
+	$(OBJDUMP) -S $(ELF) > $(LIST)
+
+$(ELF): $(OBJDIR) $(OBJS) $(LDSCRIPT) $(LIB_DIR)/lib$(LIBNAME).a
+	@printf "  LD      $(ELF)\n"
+	$(LD) $(LDFLAGS) $(ARCH_FLAGS) $(OBJS) $(LDLIBS) -o $(ELF)
+
+clean:
+	@printf "  CLEAN\n"
+	$(RM) $(OBJS) $(OBJDIR)/*.d $(ELF) $(HEX) $(LIST) $(OBJDIR)/*.map
+	$(RMDIR) $(OBJDIR)
+
+flash: $(BIN)
+	@printf "  FLASH  $(BIN)\n"
+	$(STFLASH) write $(BIN) 0x8000000
+
+boot: $(BIN)
+	@printf "  LOAD $(BIN) through bootloader\n"
+	$(STBOOT) -b$(BOOTSPEED) $(BOOTPORT) -w $(BIN)
+
+.PHONY: clean elf hex list flash boot
+
+#-include $(OBJS:.o=.d)
diff --git a/stepper_motion/README b/stepper_motion/README
new file mode 100644
index 0000000..1acf5bf
--- /dev/null
+++ b/stepper_motion/README
@@ -0,0 +1,5 @@
+Very simple USB-CDC
+
+written for chinese devboard based on STM32F103RBT6
+
+Press H for help
\ No newline at end of file
diff --git a/stepper_motion/cdcacm.c b/stepper_motion/cdcacm.c
new file mode 100644
index 0000000..5f032ad
--- /dev/null
+++ b/stepper_motion/cdcacm.c
@@ -0,0 +1,314 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2010 Gareth McMullin <gareth@blacksphere.co.nz>
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "cdcacm.h"
+#include "user_proto.h"
+#include "main.h"
+
+// Buffer for USB Tx
+static uint8_t USB_Tx_Buffer[USB_TX_DATA_SIZE];
+static uint8_t USB_Tx_ptr = 0;
+// connection flag
+uint8_t USB_connected = 0;
+static const struct usb_device_descriptor dev = {
+	.bLength = USB_DT_DEVICE_SIZE,
+	.bDescriptorType = USB_DT_DEVICE,
+	.bcdUSB = 0x0200,
+	.bDeviceClass = USB_CLASS_CDC,
+	.bDeviceSubClass = 0,
+	.bDeviceProtocol = 0,
+	.bMaxPacketSize0 = 64,
+	.idVendor = 0x0483,
+	.idProduct = 0x5740,
+	.bcdDevice = 0x0200,
+	.iManufacturer = 1,
+	.iProduct = 2,
+	.iSerialNumber = 3,
+	.bNumConfigurations = 1,
+};
+
+char usbdatabuf[USB_RX_DATA_SIZE]; // buffer for received data
+int usbdatalen = 0;  // lenght of received data
+
+/*
+ * This notification endpoint isn't implemented. According to CDC spec its
+ * optional, but its absence causes a NULL pointer dereference in Linux
+ * cdc_acm driver.
+ */
+static const struct usb_endpoint_descriptor comm_endp[] = {{
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bEndpointAddress = 0x83,
+	.bmAttributes = USB_ENDPOINT_ATTR_INTERRUPT,
+	.wMaxPacketSize = 16,
+	.bInterval = 255,
+}};
+
+static const struct usb_endpoint_descriptor data_endp[] = {{
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bEndpointAddress = 0x01,
+	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
+	.wMaxPacketSize = 64,
+	.bInterval = 1,
+}, {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+	.bEndpointAddress = 0x82,
+	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
+	.wMaxPacketSize = 64,
+	.bInterval = 1,
+}};
+
+static const struct {
+	struct usb_cdc_header_descriptor header;
+	struct usb_cdc_call_management_descriptor call_mgmt;
+	struct usb_cdc_acm_descriptor acm;
+	struct usb_cdc_union_descriptor cdc_union;
+} __attribute__((packed)) cdcacm_functional_descriptors = {
+	.header = {
+		.bFunctionLength = sizeof(struct usb_cdc_header_descriptor),
+		.bDescriptorType = CS_INTERFACE,
+		.bDescriptorSubtype = USB_CDC_TYPE_HEADER,
+		.bcdCDC = 0x0110,
+	},
+	.call_mgmt = {
+		.bFunctionLength =
+			sizeof(struct usb_cdc_call_management_descriptor),
+		.bDescriptorType = CS_INTERFACE,
+		.bDescriptorSubtype = USB_CDC_TYPE_CALL_MANAGEMENT,
+		.bmCapabilities = 0,
+		.bDataInterface = 1,
+	},
+	.acm = {
+		.bFunctionLength = sizeof(struct usb_cdc_acm_descriptor),
+		.bDescriptorType = CS_INTERFACE,
+		.bDescriptorSubtype = USB_CDC_TYPE_ACM,
+		.bmCapabilities = 0,
+	},
+	.cdc_union = {
+		.bFunctionLength = sizeof(struct usb_cdc_union_descriptor),
+		.bDescriptorType = CS_INTERFACE,
+		.bDescriptorSubtype = USB_CDC_TYPE_UNION,
+		.bControlInterface = 0,
+		.bSubordinateInterface0 = 1,
+	 },
+};
+
+static const struct usb_interface_descriptor comm_iface[] = {{
+	.bLength = USB_DT_INTERFACE_SIZE,
+	.bDescriptorType = USB_DT_INTERFACE,
+	.bInterfaceNumber = 0,
+	.bAlternateSetting = 0,
+	.bNumEndpoints = 1,
+	.bInterfaceClass = USB_CLASS_CDC,
+	.bInterfaceSubClass = USB_CDC_SUBCLASS_ACM,
+	.bInterfaceProtocol = USB_CDC_PROTOCOL_AT,
+	.iInterface = 0,
+
+	.endpoint = comm_endp,
+
+	.extra = &cdcacm_functional_descriptors,
+	.extralen = sizeof(cdcacm_functional_descriptors),
+}};
+
+static const struct usb_interface_descriptor data_iface[] = {{
+	.bLength = USB_DT_INTERFACE_SIZE,
+	.bDescriptorType = USB_DT_INTERFACE,
+	.bInterfaceNumber = 1,
+	.bAlternateSetting = 0,
+	.bNumEndpoints = 2,
+	.bInterfaceClass = USB_CLASS_DATA,
+	.bInterfaceSubClass = 0,
+	.bInterfaceProtocol = 0,
+	.iInterface = 0,
+
+	.endpoint = data_endp,
+}};
+
+static const struct usb_interface ifaces[] = {{
+	.num_altsetting = 1,
+	.altsetting = comm_iface,
+}, {
+	.num_altsetting = 1,
+	.altsetting = data_iface,
+}};
+
+static const struct usb_config_descriptor config = {
+	.bLength = USB_DT_CONFIGURATION_SIZE,
+	.bDescriptorType = USB_DT_CONFIGURATION,
+	.wTotalLength = 0,
+	.bNumInterfaces = 2,
+	.bConfigurationValue = 1,
+	.iConfiguration = 0,
+	.bmAttributes = 0x80,
+	.bMaxPower = 0x32,
+
+	.interface = ifaces,
+};
+
+static const char *usb_strings[] = {
+	"Organisation, author",
+	"device",
+	"version",
+};
+
+// default line coding: B115200, 1stop, 8bits, parity none
+struct usb_cdc_line_coding linecoding = {
+	.dwDTERate   = 115200,
+	.bCharFormat = USB_CDC_1_STOP_BITS,
+	.bParityType = USB_CDC_NO_PARITY,
+	.bDataBits   = 8,
+};
+
+/* Buffer to be used for control requests. */
+uint8_t usbd_control_buffer[128];
+
+/**
+ * This function runs every time it gets a request for control parameters get/set
+ * parameter SET_LINE_CODING used to change USART1 parameters: if you want to
+ * change them, just connect through USB with required parameters
+ */
+static int cdcacm_control_request(usbd_device *usbd_dev, struct usb_setup_data *req, uint8_t **buf,
+		uint16_t *len, void (**complete)(usbd_device *usbd_dev, struct usb_setup_data *req)){
+	(void)complete;
+	(void)buf;
+	(void)usbd_dev;
+	char local_buf[10];
+	struct usb_cdc_line_coding  lc;
+
+	switch (req->bRequest) {
+	case SET_CONTROL_LINE_STATE:{
+		if(req->wValue){ // terminal is opened
+			USB_connected = 1;
+		}else{ // terminal is closed
+			USB_connected = 0;
+		}
+		/*
+		 * This Linux cdc_acm driver requires this to be implemented
+		 * even though it's optional in the CDC spec, and we don't
+		 * advertise it in the ACM functional descriptor.
+		 */
+		struct usb_cdc_notification *notif = (void *)local_buf;
+		/* We echo signals back to host as notification. */
+		notif->bmRequestType = 0xA1;
+		notif->bNotification = USB_CDC_NOTIFY_SERIAL_STATE;
+		notif->wValue = 0;
+		notif->wIndex = 0;
+		notif->wLength = 2;
+		local_buf[8] = req->wValue & 3;
+		local_buf[9] = 0;
+		usbd_ep_write_packet(usbd_dev, 0x83, local_buf, 10);
+	}break;
+	case SET_LINE_CODING:
+		if (!len || (*len != sizeof(struct usb_cdc_line_coding)))
+			return 0;
+		memcpy((void *)&lc, (void *)*buf, *len);
+		// Mark & Space parity don't support by hardware, check it
+		if(lc.bParityType == USB_CDC_MARK_PARITY || lc.bParityType == USB_CDC_SPACE_PARITY){
+			return 0; // error
+		}else{
+//			memcpy((void *)&linecoding, (void *)&lc, sizeof(struct usb_cdc_line_coding));
+//			UART_setspeed(USART1, &linecoding);
+		}
+	break;
+	case GET_LINE_CODING: // return linecoding buffer
+		if(len && *len == sizeof(struct usb_cdc_line_coding))
+			memcpy((void *)*buf, (void *)&linecoding, sizeof(struct usb_cdc_line_coding));
+		//usbd_ep_write_packet(usbd_dev, 0x83, (char*)&linecoding, sizeof(linecoding));
+	break;
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+static void cdcacm_data_rx_cb(usbd_device *usbd_dev, uint8_t ep){
+	(void)ep;
+	int len = usbd_ep_read_packet(usbd_dev, 0x01, usbdatabuf + usbdatalen, USB_RX_DATA_SIZE - usbdatalen);
+	usbdatalen += len;
+	if(usbdatalen >= USB_RX_DATA_SIZE){ // buffer overflow - drop all its contents
+		usbdatalen = 0;
+	}
+}
+
+static void cdcacm_data_tx_cb(usbd_device *usbd_dev, uint8_t ep){
+	(void)ep;
+	(void)usbd_dev;
+
+	usb_send_buffer();
+}
+
+static void cdcacm_set_config(usbd_device *usbd_dev, uint16_t wValue)
+{
+	(void)wValue;
+	(void)usbd_dev;
+
+	usbd_ep_setup(usbd_dev, 0x01, USB_ENDPOINT_ATTR_BULK, USB_RX_DATA_SIZE, cdcacm_data_rx_cb);
+	usbd_ep_setup(usbd_dev, 0x82, USB_ENDPOINT_ATTR_BULK, USB_TX_DATA_SIZE, cdcacm_data_tx_cb);
+	usbd_ep_setup(usbd_dev, 0x83, USB_ENDPOINT_ATTR_INTERRUPT, 16, NULL);
+
+	usbd_register_control_callback(
+				usbd_dev,
+				USB_REQ_TYPE_CLASS | USB_REQ_TYPE_INTERFACE,
+				USB_REQ_TYPE_TYPE | USB_REQ_TYPE_RECIPIENT,
+				cdcacm_control_request);
+}
+
+static usbd_device *current_usb = NULL;
+
+usbd_device *USB_init(){
+	current_usb = usbd_init(&stm32f103_usb_driver, &dev, &config,
+		usb_strings, 3, usbd_control_buffer, sizeof(usbd_control_buffer));
+	if(!current_usb) return NULL;
+	usbd_register_set_config_callback(current_usb, cdcacm_set_config);
+	return current_usb;
+}
+
+mutex_t send_block_mutex = MUTEX_UNLOCKED;
+/**
+ * Put byte into USB buffer to send
+ * @param byte - a byte to put into a buffer
+ */
+void usb_send(uint8_t byte){
+	mutex_lock(&send_block_mutex);
+	USB_Tx_Buffer[USB_Tx_ptr++] = byte;
+	mutex_unlock(&send_block_mutex);
+	if(USB_Tx_ptr == USB_TX_DATA_SIZE){ // buffer can be overflowed - send it!
+		usb_send_buffer();
+	}
+}
+
+/**
+ * Send all data in buffer over USB
+ * this function runs when buffer is full or on SysTick
+ */
+void usb_send_buffer(){
+	if(MUTEX_LOCKED == mutex_trylock(&send_block_mutex)) return;
+	if(USB_Tx_ptr){
+		if(current_usb && USB_connected){
+			// usbd_ep_write_packet return 0 if previous packet isn't transmit yet
+			while(USB_Tx_ptr != usbd_ep_write_packet(current_usb, 0x82, USB_Tx_Buffer, USB_Tx_ptr));
+			usbd_poll(current_usb);
+		}
+		USB_Tx_ptr = 0;
+	}
+	mutex_unlock(&send_block_mutex);
+}
diff --git a/stepper_motion/cdcacm.h b/stepper_motion/cdcacm.h
new file mode 100644
index 0000000..1051d83
--- /dev/null
+++ b/stepper_motion/cdcacm.h
@@ -0,0 +1,54 @@
+/*
+ * ccdcacm.h
+ *
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#pragma once
+#ifndef __CCDCACM_H__
+#define __CCDCACM_H__
+
+#include <libopencm3/usb/usbd.h>
+
+// commands through EP0
+#define SEND_ENCAPSULATED_COMMAND   0x00
+#define GET_ENCAPSULATED_RESPONSE   0x01
+#define SET_COMM_FEATURE            0x02
+#define GET_COMM_FEATURE            0x03
+#define CLEAR_COMM_FEATURE          0x04
+#define SET_LINE_CODING             0x20
+#define GET_LINE_CODING             0x21
+#define SET_CONTROL_LINE_STATE      0x22
+#define SEND_BREAK                  0x23
+
+// Size of input/output buffers
+#define USB_TX_DATA_SIZE            64
+#define USB_RX_DATA_SIZE            64
+
+// USB connection flag
+extern uint8_t USB_connected;
+extern struct usb_cdc_line_coding linecoding;
+
+extern char usbdatabuf[];
+extern int usbdatalen;
+
+usbd_device *USB_init();
+void usb_send(uint8_t byte);
+void usb_send_buffer();
+
+#endif // __CCDCACM_H__
diff --git a/stepper_motion/hardware_ini.c b/stepper_motion/hardware_ini.c
new file mode 100644
index 0000000..91bf8ce
--- /dev/null
+++ b/stepper_motion/hardware_ini.c
@@ -0,0 +1,99 @@
+/*
+ * hardware_ini.c - functions for HW initialisation
+ *
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+/*
+ * All hardware-dependent initialisation & definition should be placed here
+ * and in hardware_ini.h
+ *
+ */
+
+#include "main.h"
+#include "hardware_ini.h"
+
+/**
+ * GPIO initialisaion: clocking + pins setup
+ */
+void GPIO_init(){
+	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN |
+			RCC_APB2ENR_IOPBEN | RCC_APB2ENR_IOPCEN | RCC_APB2ENR_IOPDEN |
+			RCC_APB2ENR_IOPEEN);
+/*
+	// Buttons: pull-up input
+	gpio_set_mode(BTNS_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN,
+			BTN_S2_PIN | BTN_S3_PIN);
+	// turn on pull-up
+	gpio_set(BTNS_PORT, BTN_S2_PIN | BTN_S3_PIN);
+	// LEDS: opendrain output
+	gpio_set_mode(LEDS_PORT, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN,
+			LED_D1_PIN | LED_D2_PIN);
+	// turn off LEDs
+	gpio_set(LEDS_PORT, LED_D1_PIN | LED_D2_PIN);
+	*/
+/*
+	// USB_DISC: push-pull
+	gpio_set_mode(USB_DISC_PORT, GPIO_MODE_OUTPUT_2_MHZ,
+				GPIO_CNF_OUTPUT_PUSHPULL, USB_DISC_PIN);
+	// USB_POWER: open drain, externall pull down with R7 (22k)
+	gpio_set_mode(USB_POWER_PORT, GPIO_MODE_INPUT,
+				GPIO_CNF_INPUT_FLOAT, USB_POWER_PIN);
+*/
+}
+
+
+/*
+ * SysTick used for system timer with period of 1ms
+ */
+void SysTick_init(){
+	systick_set_clocksource(STK_CSR_CLKSOURCE_AHB_DIV8); // Systyck: 72/8=9MHz
+	systick_set_reload(8999); // 9000 pulses: 1kHz
+	systick_interrupt_enable();
+	systick_counter_enable();
+}
+
+/*
+// check buttons S2/S3
+void check_btns(){
+	static uint8_t oldstate[2] = {1,1}; // old buttons state
+	uint8_t newstate[2], i;
+	static uint32_t Old_timer[2] = {0,0};
+	newstate[0] = gpio_get(BTNS_PORT, BTN_S2_PIN) ? 1 : 0;
+	newstate[1] = gpio_get(BTNS_PORT, BTN_S3_PIN) ? 1 : 0;
+	for(i = 0; i < 2; i++){
+		uint8_t new = newstate[i];
+		// pause for 60ms
+		uint32_t O = Old_timer[i];
+		if(O){
+			if(Timer - O > 60 || O > Timer){
+				P("Button S");
+				usb_send('2' + i);
+				if(new) P("released");
+				else P("pressed");
+				newline();
+				oldstate[i] = new;
+				Old_timer[i] = 0;
+			}
+		}
+		else if(new != oldstate[i]){
+			Old_timer[i] = Timer;
+		}
+	}
+}
+*/
diff --git a/stepper_motion/hardware_ini.h b/stepper_motion/hardware_ini.h
new file mode 100644
index 0000000..5e00745
--- /dev/null
+++ b/stepper_motion/hardware_ini.h
@@ -0,0 +1,58 @@
+/*
+ * hardware_ini.h
+ *
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#pragma once
+#ifndef __HARDWARE_INI_H__
+#define __HARDWARE_INI_H__
+
+/*
+ * Timers:
+ * SysTick - system time
+ */
+
+
+void GPIO_init();
+void SysTick_init();
+
+/*
+ * USB interface
+ * connect boot1 jumper to gnd, boot0 to gnd; and reconnect boot0 to +3.3 to boot flash
+ */
+/*
+// USB_DICS (disconnect) - PC11
+#define USB_DISC_PIN		GPIO11
+#define USB_DISC_PORT		GPIOC
+// USB_POWER (high level when USB connected to PC)
+#define USB_POWER_PIN		GPIO10
+#define USB_POWER_PORT		GPIOC
+// change signal level on USB diconnect pin
+#define usb_disc_high()   gpio_set(USB_DISC_PORT, USB_DISC_PIN)
+#define usb_disc_low()    gpio_clear(USB_DISC_PORT, USB_DISC_PIN)
+// in case of n-channel FET on 1.5k pull-up change on/off disconnect means low level
+// in case of pnp bipolar transistor or p-channel FET on 1.5k pull-up disconnect means high level
+#define usb_disconnect()  usb_disc_high()
+#define usb_connect()     usb_disc_low()
+*/
+// my simple devboard have no variants for programmed connection/disconnection of USB
+#define usb_disconnect()
+#define usb_connect()
+
+#endif // __HARDWARE_INI_H__
diff --git a/stepper_motion/ld/devices.data b/stepper_motion/ld/devices.data
new file mode 100644
index 0000000..7f29538
--- /dev/null
+++ b/stepper_motion/ld/devices.data
@@ -0,0 +1,9 @@
+stm32f103?4* stm32f1 ROM=16K RAM=6K
+stm32f103?6* stm32f1 ROM=32K RAM=10K
+stm32f103?8* stm32f1 ROM=64K RAM=20K
+stm32f103?b* stm32f1 ROM=128K RAM=20K
+stm32f103?c* stm32f1 ROM=256K RAM=48K
+stm32f103?d* stm32f1 ROM=384K RAM=64K
+stm32f103?e* stm32f1 ROM=512K RAM=64K
+stm32f103?f* stm32f1 ROM=768K RAM=96K
+stm32f103?g* stm32f1 ROM=1024K RAM=96K
diff --git a/stepper_motion/ld/stm32f103x4.ld b/stepper_motion/ld/stm32f103x4.ld
new file mode 100644
index 0000000..efed65e
--- /dev/null
+++ b/stepper_motion/ld/stm32f103x4.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 16K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 6K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103x6.ld b/stepper_motion/ld/stm32f103x6.ld
new file mode 100644
index 0000000..13f05f9
--- /dev/null
+++ b/stepper_motion/ld/stm32f103x6.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH =  32K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 10K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103x8.ld b/stepper_motion/ld/stm32f103x8.ld
new file mode 100644
index 0000000..2c4640f
--- /dev/null
+++ b/stepper_motion/ld/stm32f103x8.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH =  64K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 20K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103xB.ld b/stepper_motion/ld/stm32f103xB.ld
new file mode 100644
index 0000000..138444d
--- /dev/null
+++ b/stepper_motion/ld/stm32f103xB.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 128K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 20K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103xC.ld b/stepper_motion/ld/stm32f103xC.ld
new file mode 100644
index 0000000..fda76bf
--- /dev/null
+++ b/stepper_motion/ld/stm32f103xC.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 256K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 48K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103xD.ld b/stepper_motion/ld/stm32f103xD.ld
new file mode 100644
index 0000000..0f996c2
--- /dev/null
+++ b/stepper_motion/ld/stm32f103xD.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 384K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 64K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103xE.ld b/stepper_motion/ld/stm32f103xE.ld
new file mode 100644
index 0000000..b0fcb69
--- /dev/null
+++ b/stepper_motion/ld/stm32f103xE.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 512K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 64K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103xF.ld b/stepper_motion/ld/stm32f103xF.ld
new file mode 100644
index 0000000..62d47db
--- /dev/null
+++ b/stepper_motion/ld/stm32f103xF.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 768K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 96K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/ld/stm32f103xG.ld b/stepper_motion/ld/stm32f103xG.ld
new file mode 100644
index 0000000..0c0c968
--- /dev/null
+++ b/stepper_motion/ld/stm32f103xG.ld
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for STM32F100x4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 1024K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH =  96K
+}
+
+/* Include the common ld script. */
+INCLUDE libopencm3_stm32f1.ld
+
diff --git a/stepper_motion/main.c b/stepper_motion/main.c
new file mode 100644
index 0000000..18fe34a
--- /dev/null
+++ b/stepper_motion/main.c
@@ -0,0 +1,89 @@
+/*
+ * main.c
+ *
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include "main.h"
+#include "hardware_ini.h"
+#include "cdcacm.h"
+#include "steppers.h"
+
+volatile uint32_t Timer = 0; // global timer (milliseconds)
+usbd_device *usbd_dev;
+
+int main(){
+	uint32_t Old_timer = 0;
+
+	// RCC clocking: 8MHz oscillator -> 72MHz system
+	rcc_clock_setup_in_hse_8mhz_out_72mhz();
+
+	GPIO_init();
+
+	usb_disconnect(); // turn off USB while initializing all
+	steppers_init();
+
+	// USB
+	usbd_dev = USB_init();
+
+	// SysTick is a system timer with 1ms period
+	SysTick_init();
+
+	// wait a little and then turn on USB pullup
+//	for (i = 0; i < 0x800000; i++)
+//		__asm__("nop");
+
+	usb_connect(); // turn on USB
+
+	while(1){
+		usbd_poll(usbd_dev);
+		if(usbdatalen){ // there's something in USB buffer
+			usbdatalen = parce_incoming_buf(usbdatabuf, usbdatalen);
+		}
+		//check_and_parce_UART(USART1); // also check data in UART buffers
+		if(Timer - Old_timer > 999){ // one-second cycle
+			Old_timer += 1000;
+		}else if(Timer < Old_timer){ // Timer overflow
+			Old_timer = 0;
+		}
+	}
+}
+
+
+/**
+ * SysTick interrupt: increment global time & send data buffer through USB
+ */
+void sys_tick_handler(){
+	Timer++;
+	usbd_poll(usbd_dev);
+	usb_send_buffer();
+}
+
+// pause function, delay in ms
+void Delay(uint16_t _U_ time){
+	uint32_t waitto = Timer + time;
+	while(Timer < waitto);
+}
+
+/**
+ * print current time in milliseconds: 4 bytes for ovrvlow + 4 bytes for time
+ * with ' ' as delimeter
+ */
+void print_time(){
+	print_int(Timer);
+}
diff --git a/stepper_motion/main.h b/stepper_motion/main.h
new file mode 100644
index 0000000..4de99af
--- /dev/null
+++ b/stepper_motion/main.h
@@ -0,0 +1,54 @@
+/*
+ * main.h
+ *
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+
+#pragma once
+#ifndef __MAIN_H__
+#define __MAIN_H__
+
+#include <stdlib.h>
+#include <string.h>					// memcpy
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/usart.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/usb/cdc.h>
+#include <libopencm3/usb/usbd.h>
+#include <libopencm3/cm3/systick.h>
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/adc.h>
+#include <libopencm3/stm32/dma.h>
+#include <libopencm3/stm32/spi.h>
+
+#define ADC_CHANNELS_NUMBER    (10)
+
+#include "sync.h" // mutexes
+#include "user_proto.h"
+
+#define _U_    __attribute__((__unused__))
+#define  U8(x)  ((uint8_t)  x)
+#define U16(x)  ((uint16_t) x)
+#define U32(x)  ((uint32_t) x)
+
+extern volatile uint32_t Timer; // global timer (milliseconds)
+void Delay(uint16_t time);
+
+#endif // __MAIN_H__
+
diff --git a/stepper_motion/steppers.c b/stepper_motion/steppers.c
new file mode 100644
index 0000000..9c9f082
--- /dev/null
+++ b/stepper_motion/steppers.c
@@ -0,0 +1,150 @@
+/*
+ * steppers.c
+ *
+ * Copyright 2015 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include "steppers.h"
+#include "user_proto.h"
+#include <libopencm3/stm32/timer.h>
+
+
+volatile int32_t Glob_steps = 0;
+volatile int Dir = 0; // 0 - stop, 1 - move to +, -1 - move to -
+int32_t stepper_period = STEPPER_DEFAULT_PERIOD;
+
+/**
+ * Init TIM2_CH3 (& remap to 5V tolerant PB10) [STEP] and PB11 [DIR]
+ */
+void steppers_init(){
+	// Turn off JTAG & SWD, remap TIM2_CH3 to PB10 (five tolerant)
+	rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_AFIOEN | RCC_APB2ENR_IOPBEN);
+	gpio_primary_remap(AFIO_MAPR_SWJ_CFG_JTAG_OFF_SW_OFF, AFIO_MAPR_TIM2_REMAP_PARTIAL_REMAP2);
+	// setup PB10 & PB11 - both opendrain
+	gpio_set_mode(GPIO_BANK_TIM2_PR2_CH3, GPIO_MODE_OUTPUT_2_MHZ,
+		GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, GPIO_TIM2_PR2_CH3);
+	//	GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_TIM2_PR2_CH3);
+	gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_2_MHZ,
+		GPIO_CNF_OUTPUT_OPENDRAIN, GPIO11);
+	rcc_periph_clock_enable(RCC_TIM2);
+	timer_reset(TIM2);
+	// timers have frequency of 1MHz -- 1us for one step
+	timer_set_mode(TIM2, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP);
+	// 36MHz of APB1 x2 = 72MHz
+	TIM2_PSC = STEPPER_TIM_DEFAULT_PRESCALER;  // prescaler is (div - 1)
+	TIM2_CR1 = 0;
+	TIM2_CCER = 0;
+	TIM2_CCMR2 = 0;
+	TIM2_DIER = 0;
+	TIM2_SR = 0; // clear all flags
+	// PWM_OUT for TIM2_CH3
+	TIM2_CCMR2 = TIM_CCMR2_CC3S_OUT | TIM_CCMR2_OC3M_PWM1;
+	// active is low
+	TIM2_CCER = TIM_CCER_CC3E | TIM_CCER_CC3P;
+	// enable update IRQ
+	TIM2_DIER = TIM_DIER_UIE;
+	TIM2_ARR  = STEPPER_DEFAULT_PERIOD;
+	TIM2_CCR3 = STEPPER_PULSE_LEN;
+	nvic_enable_irq(NVIC_TIM2_IRQ);
+}
+
+/**
+ * Set stepper period
+ */
+uint8_t set_stepper_speed(int32_t Period){
+	if(Period > STEPPER_MIN_PERIOD && Period < STEPPER_MAX_PERIOD){
+		P("Set stepper period to ");
+		if(Period > STEPPER_TIM_MAX_ARRVAL){ // redefine prescaler when value is too large
+			TIM2_PSC = STEPPER_TIM_HUNDR_PRESCALER;
+			Period /= 100;
+			print_int(Period*100);
+			TIM2_ARR = --Period;
+		}else{ // default prescaler - for 1MHz
+			print_int(Period);
+			TIM2_PSC = STEPPER_TIM_DEFAULT_PRESCALER;
+			TIM2_ARR = --Period;
+		}
+		stepper_period = Period;
+		newline();
+	}
+	return 0;
+}
+
+void stop_stepper(){
+	TIM2_CCR3 = 0;
+	TIM2_CR1 = 0;
+	Glob_steps = 0;
+	Dir = 0;
+	gpio_set(GPIOB, GPIO11); // clear "direction"
+	P("Stopped!\n");
+}
+
+/**
+ * move stepper motor to N steps
+ * if motor is moving - just add Nsteps to current counter
+ */
+uint8_t move_stepper(int32_t Nsteps){
+	int dir = 1;
+	if(!Nsteps) return 0;
+	if(TIM2_CR1){ // moving
+		if(!gpio_get(GPIOB, GPIO11)) dir = 0; // negative direction
+		Glob_steps += Nsteps;
+		if(Glob_steps < 0){
+			Glob_steps = -Glob_steps;
+			dir = !dir;
+		}
+	}else{ // start timer if not moving
+		if(Nsteps < 0){ // change direction
+			dir = 0;
+			Nsteps = -Nsteps;
+		}
+		Glob_steps = Nsteps;
+		TIM2_ARR = stepper_period;
+		TIM2_CCR3 = STEPPER_PULSE_LEN;
+		TIM2_CR1 = TIM_CR1_CEN;
+	}
+	// set/clear direction
+	P("Rotate ");
+	if(dir){
+		gpio_set(GPIOB, GPIO11);
+	}else{
+		gpio_clear(GPIOB, GPIO11);
+		P("counter-");
+	}
+	P("clockwise to ");
+	print_int(Glob_steps);
+	P(" steps\n");
+	return 0;
+}
+
+void tim2_isr(){
+	// Next step
+	if(TIM2_SR & TIM_SR_UIF){
+		if(--Glob_steps < 1){ // stop timer as steps ends
+			stop_stepper();
+		}
+	}
+	TIM2_SR = 0;
+}
+
+
+int32_t stepper_get_period(){
+	int32_t r = stepper_period + 1;
+	if(TIM2_PSC == STEPPER_TIM_DEFAULT_PRESCALER) return r;
+	else return r * 100;
+}
diff --git a/stepper_motion/steppers.h b/stepper_motion/steppers.h
new file mode 100644
index 0000000..cf701b7
--- /dev/null
+++ b/stepper_motion/steppers.h
@@ -0,0 +1,50 @@
+/*
+ * steppers.h
+ *
+ * Copyright 2015 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+#pragma once
+#ifndef __STEPPERS_H__
+#define __STEPPERS_H__
+
+#include "main.h"
+// minimal period - 100us (10000ticks per second)
+#define STEPPER_MIN_PERIOD      (99)
+// default period
+#define STEPPER_DEFAULT_PERIOD  (1299)
+// high (off) pulse length: 70us (minimum value according documentation is 0.5us)
+#define STEPPER_PULSE_LEN       (69)
+// TIM2 have 16bit ARR register, so max P with fixed prescaler is 65536
+#define STEPPER_TIM_MAX_ARRVAL  (65536)
+// max period allowed: 6553600us = 6.5s
+#define STEPPER_MAX_PERIOD      (6553601)
+// default prescaler for 1MHz
+#define STEPPER_TIM_DEFAULT_PRESCALER  (71)
+// prescaler for 100kHz
+#define STEPPER_TIM_HUNDR_PRESCALER    (7199)
+void steppers_init();
+
+uint8_t set_stepper_speed(int32_t Period);
+uint8_t move_stepper(int32_t Nsteps);
+void stop_stepper();
+extern volatile int32_t Glob_steps;
+#define stepper_get_steps()  (Glob_steps)
+
+extern int32_t stepper_period;
+int32_t stepper_get_period();
+#endif // __STEPPERS_H__
diff --git a/stepper_motion/sync.c b/stepper_motion/sync.c
new file mode 100644
index 0000000..ba688c3
--- /dev/null
+++ b/stepper_motion/sync.c
@@ -0,0 +1,93 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Fergus Noble <fergusnoble@gmail.com>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * TODO:
+ *   implement mutexes for other type of MCU (which doesn't have strex & ldrex)
+ */
+
+#include <libopencm3/cm3/sync.h>
+
+/* DMB is supported on CM0 */
+void __dmb()
+{
+	__asm__ volatile ("dmb");
+}
+
+/* Those are defined only on CM3 or CM4 */
+#if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
+
+uint32_t __ldrex(volatile uint32_t *addr)
+{
+	uint32_t res;
+	__asm__ volatile ("ldrex %0, [%1]" : "=r" (res) : "r" (addr));
+	return res;
+}
+
+uint32_t __strex(uint32_t val, volatile uint32_t *addr)
+{
+	uint32_t res;
+	__asm__ volatile ("strex %0, %2, [%1]"
+			  : "=&r" (res) : "r" (addr), "r" (val));
+	return res;
+}
+
+void mutex_lock(mutex_t *m)
+{
+	uint32_t status = 0;
+
+	do {
+		/* Wait until the mutex is unlocked. */
+		while (__ldrex(m) != MUTEX_UNLOCKED);
+
+		/* Try to acquire it. */
+		status = __strex(MUTEX_LOCKED, m);
+
+	/* Did we get it? If not then try again. */
+	} while (status != 0);
+
+	/* Execute the mysterious Data Memory Barrier instruction! */
+	__dmb();
+}
+
+void mutex_unlock(mutex_t *m)
+{
+	/* Ensure accesses to protected resource are finished */
+	__dmb();
+
+	/* Free the lock. */
+	*m = MUTEX_UNLOCKED;
+}
+
+/*
+ * Try to lock mutex
+ * if it's already locked or there was error in STREX, return MUTEX_LOCKED
+ * else return MUTEX_UNLOCKED
+ */
+mutex_t mutex_trylock(mutex_t *m){
+	uint32_t status = 0;
+	mutex_t old_lock = __ldrex(m); // get mutex value
+	// set mutex
+	status = __strex(MUTEX_LOCKED, m);
+	if(status == 0) __dmb();
+	else old_lock = MUTEX_LOCKED;
+	return old_lock;
+}
+
+#endif
diff --git a/stepper_motion/sync.h b/stepper_motion/sync.h
new file mode 100644
index 0000000..bfe837b
--- /dev/null
+++ b/stepper_motion/sync.h
@@ -0,0 +1,53 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Fergus Noble <fergusnoble@gmail.com>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBOPENCM3_CM3_SYNC_H
+#define LIBOPENCM3_CM3_SYNC_H
+
+void __dmb(void);
+
+/* Implements synchronisation primitives as discussed in the ARM document
+ * DHT0008A (ID081709) "ARM Synchronization Primitives" and the ARM v7-M
+ * Architecture Reference Manual.
+*/
+
+/* --- Exclusive load and store instructions ------------------------------- */
+
+/* Those are defined only on CM3 or CM4 */
+#if defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7EM__)
+
+uint32_t __ldrex(volatile uint32_t *addr);
+uint32_t __strex(uint32_t val, volatile uint32_t *addr);
+
+/* --- Convenience functions ----------------------------------------------- */
+
+/* Here we implement some simple synchronisation primitives. */
+
+typedef uint32_t mutex_t;
+
+#define MUTEX_UNLOCKED 0
+#define MUTEX_LOCKED   1
+
+void mutex_lock(mutex_t *m);
+void mutex_unlock(mutex_t *m);
+mutex_t mutex_trylock(mutex_t *m);
+
+#endif
+
+#endif
diff --git a/stepper_motion/usb_cdc_simple.bin b/stepper_motion/usb_cdc_simple.bin
new file mode 100755
index 0000000..ef8526f
Binary files /dev/null and b/stepper_motion/usb_cdc_simple.bin differ
diff --git a/stepper_motion/user_proto.c b/stepper_motion/user_proto.c
new file mode 100644
index 0000000..67bc4f2
--- /dev/null
+++ b/stepper_motion/user_proto.c
@@ -0,0 +1,208 @@
+/*
+ * user_proto.c
+ *
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include "cdcacm.h"
+#include "main.h"
+#include "hardware_ini.h"
+#include "steppers.h"
+
+// integer value given by user
+static volatile int32_t User_value = 0;
+enum{
+	UVAL_START,		// user start to write integer value
+	UVAL_ENTERED,	// value entered but not printed
+	UVAL_BAD		// entered bad value
+};
+uint8_t Uval_ready = UVAL_BAD;
+
+int read_int(char *buf, int cnt);
+
+intfun I = NULL; // function to process entered integer
+
+#define READINT() do{i += read_int(&buf[i+1], len-i-1);}while(0)
+
+void help(){
+	P("G\tgo to N steps\n");
+	P("H\tshow this help\n");
+	P("P\tset stepper period (us)\n");
+	P("S\tstop motor\n");
+	P("T\tshow current approx. time\n");
+	P("W\tshow current steps value\n");
+	P("X\tshow current stepper period\n");
+}
+
+
+/**
+ * parce command buffer buf with length len
+ * return 0 if buffer processed or len if there's not enough data in buffer
+ */
+int parce_incoming_buf(char *buf, int len){
+	uint8_t command;
+	//uint32_t utmp;
+	int i = 0;
+	if(Uval_ready == UVAL_START){ // we are in process of user's value reading
+		i += read_int(buf, len);
+	}
+	if(Uval_ready == UVAL_ENTERED){
+		//print_int(User_value); // printout readed integer value for error control
+		Uval_ready = UVAL_BAD; // clear Uval
+		I(User_value);
+		return 0;
+	}
+	for(; i < len; i++){
+		command = buf[i];
+		if(!command) continue; // omit zero
+		switch (command){
+			case 'G':
+				I = move_stepper;
+				READINT();
+			break;
+			case 'H': // show help
+				help();
+			break;
+			case 'P':
+				I = set_stepper_speed;
+				READINT();
+			break;
+			case 'S':
+				stop_stepper();
+			break;
+			case 'T':
+				newline();
+				print_int(Timer); // be careful for Time >= 2^{31}!!!
+				newline();
+			break;
+			case 'W':
+				print_int(stepper_get_steps());
+				newline();
+			break;
+			case 'X':
+				print_int(stepper_get_period());
+				newline();
+			break;
+			case '\n': // show newline, space and tab as is
+			case '\r':
+			case ' ':
+			case '\t':
+			break;
+			default:
+				command = '?'; // echo '?' on unknown command in byte mode
+		}
+		usb_send(command); // echo readed byte
+	}
+	return 0; // all data processed - 0 bytes leave in buffer
+}
+
+/**
+ * Send char array wrd thru USB or UART
+ */
+void prnt(uint8_t *wrd){
+	if(!wrd) return;
+	while(*wrd) usb_send(*wrd++);
+}
+
+/**
+ * Read from TTY integer value given by user (in DEC).
+ *    Reading stops on first non-numeric symbol.
+ *    To work with symbol terminals reading don't stops on buffer's end,
+ *    it waits for first non-numeric char.
+ *    When working on string terminals, terminate string by '\n', 0 or any other symbol
+ * @param buf - buffer to read from
+ * @param cnt - buffer length
+ * @return amount of readed symbols
+ */
+int read_int(char *buf, int cnt){
+	int readed = 0, i;
+	static int enteredDigits; // amount of entered digits
+	static int sign; // sign of readed value
+	if(Uval_ready){ // this is first run
+		Uval_ready = UVAL_START; // clear flag
+		enteredDigits = 0; // 0 digits entered
+		User_value = 0; // clear value
+		sign = 1; // clear sign
+	}
+	if(!cnt) return 0;
+	for(i = 0; i < cnt; i++, readed++){
+		uint8_t chr = buf[i];
+		if(chr == '-'){
+			if(enteredDigits == 0){ // sign should be first
+				sign = -1;
+				continue;
+			}else{ // '-' after number - reject entered value
+				Uval_ready = UVAL_BAD;
+				break;
+			}
+		}
+		if(chr < '0' || chr > '9'){
+			if(enteredDigits)
+				Uval_ready = UVAL_ENTERED;
+			else
+				Uval_ready = UVAL_BAD; // bad symbol
+			break;
+		}
+		User_value = User_value * 10 + (int32_t)(chr - '0');
+		enteredDigits++;
+	}
+	if(Uval_ready == UVAL_ENTERED) // reading has met an non-numeric character
+		User_value *= sign;
+	return readed;
+}
+
+/**
+ * Print buff as hex values
+ * @param buf - buffer to print
+ * @param l   - buf length
+ * @param s   - function to send a byte
+ */
+void print_hex(uint8_t *buff, uint8_t l){
+	void putc(uint8_t c){
+		if(c < 10)
+			usb_send(c + '0');
+		else
+			usb_send(c + 'a' - 10);
+	}
+	usb_send('0'); usb_send('x'); // prefix 0x
+	while(l--){
+		putc(buff[l] >> 4);
+		putc(buff[l] & 0x0f);
+	}
+}
+
+/**
+ * Print decimal integer value
+ * @param N - value to print
+ * @param s - function to send a byte
+ */
+void print_int(int32_t N){
+	uint8_t buf[10], L = 0;
+	if(N < 0){
+		usb_send('-');
+		N = -N;
+	}
+	if(N){
+		while(N){
+			buf[L++] = N % 10 + '0';
+			N /= 10;
+		}
+		while(L--) usb_send(buf[L]);
+	}else usb_send('0');
+}
+
diff --git a/stepper_motion/user_proto.h b/stepper_motion/user_proto.h
new file mode 100644
index 0000000..4b0fc3a
--- /dev/null
+++ b/stepper_motion/user_proto.h
@@ -0,0 +1,47 @@
+/*
+ * user_proto.h
+ *
+ * Copyright 2014 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#pragma once
+#ifndef __USER_PROTO_H__
+#define __USER_PROTO_H__
+
+#include "cdcacm.h"
+
+// shorthand for prnt
+#define P(arg)   do{prnt((uint8_t*)arg);}while(0)
+// debug message - over USB
+#ifdef EBUG
+	#define DBG(a)    do{prnt((uint8_t*)a);}while(0)
+#else
+	#define DBG(a)
+#endif
+
+typedef uint8_t (*intfun)(int32_t);
+
+void prnt(uint8_t *wrd);
+#define newline()   usb_send('\n')
+
+void print_int(int32_t N);
+void print_hex(uint8_t *buff, uint8_t l);
+
+int parce_incoming_buf(char *buf, int len);
+
+#endif // __USER_PROTO_H__