loopback CAN mode

F0-nolib/canbus/src/CANbus.geany

@@ -0,0 +1,32 @@
+[editor]
+line_wrapping=false
+line_break_column=100
+auto_continue_multiline=true
+
+[file_prefs]
+final_new_line=true
+ensure_convert_new_lines=true
+strip_trailing_spaces=true
+replace_tabs=true
+
+[indentation]
+indent_width=4
+indent_type=0
+indent_hard_tab_width=4
+detect_indent=false
+detect_indent_width=false
+indent_mode=3
+
+[project]
+name=CANbus
+base_path=/home/eddy/Docs/SAO/ELECTRONICS/STM32/F0-srcs/canbus/src
+
+[long line marker]
+long_line_behaviour=1
+long_line_column=100
+
+[files]
+current_page=-1
+
+[VTE]
+last_dir=/home/eddy

F0-nolib/canbus/src/Makefile

@@ -0,0 +1,145 @@
+BINARY		= canbus
+BOOTPORT	?= /dev/ttyUSB0
+BOOTSPEED	?= 57600
+# MCU FAMILY
+FAMILY		= F0
+# MCU code
+MCU			= F042x6
+# hardware definitions
+DEFS		+= -DUSARTNUM=1
+#DEFS		+= -DCHECK_TMOUT
+#DEFS		+= -DEBUG
+# change this linking script depending on particular MCU model,
+# for example, if you have STM32F103VBT6, you should write:
+LDSCRIPT	= ld/stm32f042k.ld
+
+INDEPENDENT_HEADERS=
+
+FP_FLAGS	?= -msoft-float
+ASM_FLAGS	= -mthumb -mcpu=cortex-m0 -march=armv6-m -mtune=cortex-m0
+ARCH_FLAGS	= $(ASM_FLAGS) $(FP_FLAGS)
+
+###############################################################################
+# Executables
+OPREFIX		?= /opt/bin/arm-none-eabi
+#PREFIX		?= /usr/x86_64-pc-linux-gnu/arm-none-eabi/gcc-bin/7.3.0/arm-none-eabi
+PREFIX		?= $(OPREFIX)
+
+RM			:= rm -f
+RMDIR		:= rmdir
+CC			:= $(PREFIX)-gcc
+LD			:= $(PREFIX)-gcc
+AR			:= $(PREFIX)-ar
+AS			:= $(PREFIX)-as
+OBJCOPY		:= $(OPREFIX)-objcopy
+OBJDUMP		:= $(OPREFIX)-objdump
+GDB			:= $(OPREFIX)-gdb
+STFLASH		:= $(shell which st-flash)
+STBOOT		:= $(shell which stm32flash)
+
+###############################################################################
+# Source files
+OBJDIR 		= mk
+LDSCRIPT	?= $(BINARY).ld
+SRC			:= $(wildcard *.c)
+OBJS		:= $(addprefix $(OBJDIR)/, $(SRC:%.c=%.o))
+STARTUP		= $(OBJDIR)/startup.o
+OBJS 		+= $(STARTUP)
+DEPS		:= $(OBJS:.o=.d)
+
+INC_DIR ?= ../../inc
+
+INCLUDE 	:= -I$(INC_DIR)/F0 -I$(INC_DIR)/cm
+LIB_DIR		:= $(INC_DIR)/ld
+
+###############################################################################
+# C flags
+CFLAGS		+= -O2 -g -MD -D__thumb2__=1
+CFLAGS		+= -Wall -Wextra -Wshadow -Wimplicit-function-declaration
+CFLAGS		+= -Wredundant-decls $(INCLUDE)
+# -Wmissing-prototypes -Wstrict-prototypes
+CFLAGS		+= -fno-common -ffunction-sections -fdata-sections
+
+###############################################################################
+# Linker flags
+LDFLAGS		+= --static -nostartfiles
+#--specs=nano.specs
+LDFLAGS		+= -L$(LIB_DIR)
+LDFLAGS		+= -T$(LDSCRIPT)
+LDFLAGS		+= -Wl,-Map=$(OBJDIR)/$(BINARY).map
+LDFLAGS		+= -Wl,--gc-sections
+
+###############################################################################
+# Used libraries
+LDLIBS		+= -Wl,--start-group -lc -lgcc -Wl,--end-group
+LDLIBS		+= $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
+
+DEFS		+= -DSTM32$(FAMILY) -DSTM32$(MCU)
+
+#.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 list
+
+elf: $(ELF)
+bin: $(BIN)
+hex: $(HEX)
+list: $(LIST)
+
+ifneq ($(MAKECMDGOALS),clean)
+-include $(DEPS)
+endif
+
+$(OBJDIR):
+	mkdir $(OBJDIR)
+
+$(STARTUP): $(INC_DIR)/startup/vector.c
+	$(CC) $(CFLAGS) $(DEFS) $(INCLUDE) $(ARCH_FLAGS) -o $@ -c $<
+
+$(OBJDIR)/%.o: %.c
+	@echo "  CC      $<"
+	$(CC) $(CFLAGS) $(DEFS) $(INCLUDE) $(ARCH_FLAGS) -o $@ -c $<
+
+#$(OBJDIR)/%.d: %.c $(OBJDIR)
+#	$(CC) -MM -MG $< | sed -e 's,^\([^:]*\)\.o[ ]*:,$(@D)/\1.o $(@D)/\1.d:,' >$@
+
+$(BIN): $(ELF)
+	@echo "  OBJCOPY $(BIN)"
+	$(OBJCOPY) -Obinary $(ELF) $(BIN)
+
+$(HEX): $(ELF)
+	@echo "  OBJCOPY $(HEX)"
+	$(OBJCOPY) -Oihex $(ELF) $(HEX)
+
+$(LIST): $(ELF)
+	@echo "  OBJDUMP $(LIST)"
+	$(OBJDUMP) -S $(ELF) > $(LIST)
+
+$(ELF): $(OBJDIR) $(OBJS)
+	@echo "  LD      $(ELF)"
+	$(LD) $(LDFLAGS) $(ARCH_FLAGS) $(OBJS) $(LDLIBS) -o $(ELF)
+
+clean:
+	@echo "  CLEAN"
+	$(RM) $(OBJS) $(DEPS) $(ELF) $(HEX) $(LIST) $(OBJDIR)/*.map *.d
+	@rmdir $(OBJDIR) 2>/dev/null || true
+
+
+flash: $(BIN)
+	@echo "  FLASH  $(BIN)"
+	$(STFLASH) write $(BIN) 0x8000000
+
+boot: $(BIN)
+	@echo "  LOAD $(BIN) through bootloader"
+	$(STBOOT) -b$(BOOTSPEED) $(BOOTPORT) -w $(BIN)
+
+gentags:
+	CFLAGS="$(CFLAGS) $(DEFS)" geany -g $(BINARY).c.tags *[hc] 2>/dev/null
+
+.PHONY: clean flash boot gentags

F0-nolib/canbus/src/can.c

@@ -0,0 +1,131 @@
+/*
+ *                                                                                                  geany_encoding=koi8-r
+ * can.c
+ *
+ * Copyright 2018 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 "can.h"
+#include "hardware.h"
+#include "usart.h"
+
+#define CMD_TOGGLE (0xDA)
+#define CAN_ID_MASK (0xFF70U)
+#define CAN_ID1 (0x651U)
+#define CAN_ID2 (0x652U)
+#define FILTER_LIST (0) /* 0: filter mode = identifier mask, 1: filter mode = identifier list */
+
+#define CAN_FLAG_GOTDUMMY (1)
+static uint8_t CAN_addr = 255;
+static uint8_t CAN_flags = 0;
+
+// get CAN address data from GPIO pins
+void readCANaddr(){
+    CAN_addr = READ_CAN_INV_ADDR();
+    CAN_addr = ~CAN_addr & 0x7;
+}
+
+uint8_t getCANaddr(){
+    return CAN_addr;
+}
+
+void CAN_setup(){
+    if(CAN_addr == 255) readCANaddr();
+    // Configure GPIO: PB8 - CAN_Rx, PB9 - CAN_Tx
+    /* (1) Select AF mode (10) on PB8 and PB9 */
+    /* (2) AF4 for CAN signals */
+    GPIOB->MODER = (GPIOB->MODER & ~(GPIO_MODER_MODER8 | GPIO_MODER_MODER9))
+                 | (GPIO_MODER_MODER8_AF | GPIO_MODER_MODER9_AF); /* (1) */
+    GPIOB->AFR[1] = (GPIOB->AFR[1] &~ (GPIO_AFRH_AFRH0 | GPIO_AFRH_AFRH1))\
+                  | (4 << (0 * 4)) | (4 << (1 * 4)); /* (2) */
+    /* Enable the peripheral clock CAN */
+    RCC->APB1ENR |= RCC_APB1ENR_CANEN;
+      /* Configure CAN */
+    /* (1) Enter CAN init mode to write the configuration */
+    /* (2) Wait the init mode entering */
+    /* (3) Exit sleep mode */
+    /* (4) Loopback mode, set timing to 1Mb/s: BS1 = 4, BS2 = 3, prescaler = 6 */
+    /* (5) Leave init mode */
+    /* (6) Wait the init mode leaving */
+    /* (7) Enter filter init mode, (16-bit + mask, filter 0 for FIFO 0) */
+    /* (8) Acivate filter 0 */
+    /* (9) Identifier list mode */
+    /* (11) Set the Id list */
+    /* (12) Set the Id + mask (all bits of standard id will care) */
+    /* (13) Leave filter init */
+    /* (14) Set FIFO0 message pending IT enable */
+    CAN->MCR |= CAN_MCR_INRQ; /* (1) */
+    while((CAN->MSR & CAN_MSR_INAK)!=CAN_MSR_INAK) /* (2) */
+    {
+    /* add time out here for a robust application */
+    }
+    CAN->MCR &=~ CAN_MCR_SLEEP; /* (3) */
+    CAN->BTR |= CAN_BTR_LBKM | 2 << 20 | 3 << 16 | 5 << 0; /* (4) */
+    CAN->MCR &=~ CAN_MCR_INRQ; /* (5) */
+    while((CAN->MSR & CAN_MSR_INAK)==CAN_MSR_INAK) /* (6) */
+    {
+    /* add time out here for a robust application */
+    }
+    CAN->FMR = CAN_FMR_FINIT; /* (7) */
+    CAN->FA1R = CAN_FA1R_FACT0; /* (8) */
+    #if (FILTER_LIST)
+    CAN->FM1R = CAN_FM1R_FBM0; /* (9) */
+    CAN->sFilterRegister[0].FR1 = CAN_ID2 << 5 | CAN_ID1 << (16+5); /* (10) */
+    #else
+    CAN->sFilterRegister[0].FR1 = CAN_ID1 << 5 | CAN_ID_MASK << 16; /* (11) */
+    #endif /* FILTER_LIST */
+
+    CAN->FMR &=~ CAN_FMR_FINIT; /* (12) */
+    CAN->IER |= CAN_IER_FMPIE0; /* (13) */
+
+    /* Configure IT */
+    /* (14) Set priority for CAN_IRQn */
+    /* (15) Enable CAN_IRQn */
+    NVIC_SetPriority(CEC_CAN_IRQn, 0); /* (16) */
+    NVIC_EnableIRQ(CEC_CAN_IRQn); /* (17) */
+}
+
+void can_proc(){
+    if(CAN_flags){
+        if(CAN_flags & CAN_FLAG_GOTDUMMY){
+            SEND("Got dummy message\n");
+        }
+        CAN_flags = 0;
+    }
+}
+
+void can_send_dummy(){
+    if((CAN->TSR & CAN_TSR_TME0) == CAN_TSR_TME0){ /* check mailbox 0 is empty */
+        CAN->sTxMailBox[0].TDTR = 1; /* fill data length = 1 */
+        CAN->sTxMailBox[0].TDLR = CMD_TOGGLE; /* fill 8-bit data */
+        CAN->sTxMailBox[0].TIR = (uint32_t)(CAN_ID1 << 21 | CAN_TI0R_TXRQ); /* fill Id field and request a transmission */
+    }
+}
+
+void cec_can_isr(){
+    uint32_t CAN_ReceiveMessage = 0;
+
+    if(CAN->RF0R & CAN_RF0R_FMP0){ /* check if a message is filtered and received by FIFO 0 */
+        LED_blink(LED1); /* Toggle LED1 */
+        CAN_ReceiveMessage = CAN->sFIFOMailBox[0].RDLR; /* read data */
+        CAN->RF0R |= CAN_RF0R_RFOM0; /* release FIFO */
+        if((CAN_ReceiveMessage & 0xFF) == CMD_TOGGLE){
+            CAN_flags |= CAN_FLAG_GOTDUMMY;
+        }
+    }
+}

F0-nolib/canbus/src/can.h

@@ -0,0 +1,37 @@
+/*
+ *                                                                                                  geany_encoding=koi8-r
+ * can.h
+ *
+ * Copyright 2018 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 __CAN_H__
+#define __CAN_H__
+
+#include "hardware.h"
+
+void readCANaddr();
+uint8_t getCANaddr();
+
+void CAN_setup();
+
+void can_send_dummy();
+void can_proc();
+
+#endif // __CAN_H__

F0-nolib/canbus/src/hardware.c

@@ -0,0 +1,43 @@
+/*
+ *                                                                                                  geany_encoding=koi8-r
+ * hardware.c - hardware-dependent macros & functions
+ *
+ * Copyright 2018 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 "hardware.h"
+#include "usart.h"
+
+void gpio_setup(void){
+    // here we turn on clocking for all periph.
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN | RCC_AHBENR_GPIOCEN | RCC_AHBENR_DMAEN;
+    // Set LEDS (PC13/14) as output
+    GPIOC->MODER = (GPIOC->MODER & ~(GPIO_MODER_MODER13  | GPIO_MODER_MODER14)
+                    ) |
+                    GPIO_MODER_MODER13_O | GPIO_MODER_MODER14_O;
+    // PB14(0), PB15(1), PA8(2) - CAN address, pullup inputs
+    GPIOA->PUPDR = (GPIOA->PUPDR & ~(GPIO_PUPDR_PUPDR8)
+                    ) |
+                    GPIO_PUPDR_PUPDR8_0;
+    GPIOB->PUPDR = (GPIOB->PUPDR & ~(GPIO_PUPDR_PUPDR14 | GPIO_PUPDR_PUPDR15)
+                    ) |
+                    GPIO_PUPDR_PUPDR14_0 | GPIO_PUPDR_PUPDR15_0;
+    pin_set(LED0_port, LED0_pin); // clear LEDs
+    pin_set(LED1_port, LED1_pin);
+}

F0-nolib/canbus/src/hardware.h

@@ -0,0 +1,52 @@
+/*
+ *                                                                                                  geany_encoding=koi8-r
+ * hardware.h
+ *
+ * Copyright 2018 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_H__
+#define __HARDWARE_H__
+
+#include "stm32f0.h"
+
+#define CONCAT(a,b)     a ## b
+#define STR_HELPER(s)   #s
+#define STR(s)          STR_HELPER(s)
+
+#define FORMUSART(X)    CONCAT(USART, X)
+#define USARTX          FORMUSART(USARTNUM)
+
+// LEDS: 0 - PC13, 1 - PC14
+// LED0
+#define LED0_port   GPIOC
+#define LED0_pin    (1<<13)
+// LED1
+#define LED1_port   GPIOC
+#define LED1_pin    (1<<14)
+
+#define LED_blink(x) pin_toggle(x ## _port, x ## _pin)
+
+
+// CAN address - PB14(0), PB15(1), PA8(2)
+#define READ_CAN_INV_ADDR()  (((GPIOA->IDR & (1<<8))>>6)|((GPIOB->IDR & (3<<14))>>14))
+
+void gpio_setup(void);
+
+#endif // __HARDWARE_H__

F0-nolib/canbus/src/ld/stm32f042k.ld

@@ -0,0 +1,12 @@
+/* Linker script for STM32F042x6, 32K flash, 6K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+    rom   (rx) : ORIGIN = 0x08000000, LENGTH = 32K
+    ram  (rwx) : ORIGIN = 0x20000000, LENGTH = 6K
+}
+
+/* Include the common ld script. */
+INCLUDE stm32f0.ld
+

F0-nolib/canbus/src/main.c

@@ -0,0 +1,123 @@
+/*
+ * main.c
+ *
+ * Copyright 2017 Edward V. Emelianoff <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 "hardware.h"
+#include "usart.h"
+#include "can.h"
+
+volatile uint32_t Tms = 0;
+
+/* Called when systick fires */
+void sys_tick_handler(void){
+    ++Tms;
+}
+
+void iwdg_setup(){
+    /* Enable the peripheral clock RTC */
+    /* (1) Enable the LSI (40kHz) */
+    /* (2) Wait while it is not ready */
+    RCC->CSR |= RCC_CSR_LSION; /* (1) */
+    while((RCC->CSR & RCC_CSR_LSIRDY) != RCC_CSR_LSIRDY); /* (2) */
+    /* Configure IWDG */
+    /* (1) Activate IWDG (not needed if done in option bytes) */
+    /* (2) Enable write access to IWDG registers */
+    /* (3) Set prescaler by 64 (1.6ms for each tick) */
+    /* (4) Set reload value to have a rollover each 2s */
+    /* (5) Check if flags are reset */
+    /* (6) Refresh counter */
+    IWDG->KR = IWDG_START; /* (1) */
+    IWDG->KR = IWDG_WRITE_ACCESS; /* (2) */
+    IWDG->PR = IWDG_PR_PR_1; /* (3) */
+    IWDG->RLR = 1250; /* (4) */
+    while(IWDG->SR); /* (5) */
+    IWDG->KR = IWDG_REFRESH; /* (6) */
+}
+
+int main(void){
+    uint32_t lastT = 0;
+    int L;
+    char *txt;
+    sysreset();
+    SysTick_Config(6000, 1);
+    gpio_setup();
+    usart_setup();
+    iwdg_setup();
+    readCANaddr();
+    CAN_setup();
+
+    SEND("Greetings! My address is ");
+    printu(getCANaddr());
+    newline();
+    if(RCC->CSR & RCC_CSR_IWDGRSTF){ // watchdog reset occured
+        SEND("WDGRESET=1\n");
+    }
+    if(RCC->CSR & RCC_CSR_SFTRSTF){ // software reset occured
+        SEND("SOFTRESET=1\n");
+    }
+    RCC->CSR |= RCC_CSR_RMVF; // remove reset flags
+
+    while (1){
+        IWDG->KR = IWDG_REFRESH; // refresh watchdog
+        if(lastT > Tms || Tms - lastT > 499){
+            LED_blink(LED0);
+            lastT = Tms;
+        }
+        can_proc();
+        if(usartrx()){ // usart1 received data, store in in buffer
+            L = usart_getline(&txt);
+            char _1st = txt[0];
+            if(L == 2 && txt[1] == '\n'){
+                L = 0;
+                switch(_1st){
+                    case 'C':
+                        can_send_dummy();
+                    break;
+                    case 'G':
+                        SEND("Can address: ");
+                        printu(getCANaddr());
+                        newline();
+                    break;
+                    case 'R':
+                        NVIC_SystemReset();
+                    break;
+                    case 'W':
+                        SEND("Wait for reboot\n");
+                        while(1){nop();};
+                    break;
+                    default: // help
+                        SEND(
+                        "'C' - send dummy byte over CAN\n"
+                        "'G' - get CAN address\n"
+                        "'R' - software reset\n"
+                        "'W' - test watchdog\n"
+                        );
+                    break;
+                }
+            }
+        }
+        if(L){ // text waits for sending
+            while(LINE_BUSY == usart_send(txt, L));
+            L = 0;
+        }
+    }
+    return 0;
+}
+

F0-nolib/canbus/src/usart.c

@@ -0,0 +1,238 @@
+/*us
+ * usart.c
+ *
+ * Copyright 2017 Edward V. Emelianoff <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 "stm32f0.h"
+#include "hardware.h"
+#include "usart.h"
+#include <string.h>
+
+extern volatile uint32_t Tms;
+static int datalen[2] = {0,0}; // received data line length (including '\n')
+
+volatile int linerdy = 0,        // received data ready
+    dlen = 0,           // length of data (including '\n') in current buffer
+    bufovr = 0,         // input buffer overfull
+    txrdy = 1           // transmission done
+;
+
+
+int rbufno = 0; // current rbuf number
+static char rbuf[UARTBUFSZ][2], tbuf[UARTBUFSZ]; // receive & transmit buffers
+static char *recvdata = NULL;
+
+/**
+ * return length of received data (without trailing zero
+ */
+int usart_getline(char **line){
+    if(bufovr){
+        bufovr = 0;
+        linerdy = 0;
+        return 0;
+    }
+    *line = recvdata;
+    linerdy = 0;
+    return dlen;
+}
+
+TXstatus usart_send(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    if(len > UARTBUFSZ) return STR_TOO_LONG;
+    txrdy = 0;
+    memcpy(tbuf, str, len);
+#if USARTNUM == 2
+    DMA1_Channel4->CCR &= ~DMA_CCR_EN;
+    DMA1_Channel4->CNDTR = len;
+    DMA1_Channel4->CCR |= DMA_CCR_EN; // start transmission
+#elif USARTNUM == 1
+    DMA1_Channel2->CCR &= ~DMA_CCR_EN;
+    DMA1_Channel2->CNDTR = len;
+    DMA1_Channel2->CCR |= DMA_CCR_EN;
+#else
+#error "Not implemented"
+#endif
+    return ALL_OK;
+}
+
+TXstatus usart_send_blocking(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    int i;
+    bufovr = 0;
+    for(i = 0; i < len; ++i){
+        USARTX -> TDR = *str++;
+        while(!(USARTX->ISR & USART_ISR_TXE));
+    }
+    return ALL_OK;
+}
+
+void usart_putchar(const char ch){
+    while(!txrdy);
+    USARTX -> TDR = ch;
+    while(!(USARTX->ISR & USART_ISR_TXE));
+}
+
+void newline(){
+    while(!txrdy);
+    USARTX -> TDR = '\n';
+    while(!(USARTX->ISR & USART_ISR_TXE));
+}
+
+
+void usart_setup(){
+// Nucleo's USART2 connected to VCP proxy of st-link
+#if USARTNUM == 2
+    // setup pins: PA2 (Tx - AF1), PA15 (Rx - AF1)
+    // AF mode (AF1)
+    GPIOA->MODER = (GPIOA->MODER & ~(GPIO_MODER_MODER2|GPIO_MODER_MODER15))\
+                | (GPIO_MODER_MODER2_AF | GPIO_MODER_MODER15_AF);
+    GPIOA->AFR[0] = (GPIOA->AFR[0] &~GPIO_AFRH_AFRH2) | 1 << (2 * 4); // PA2
+    GPIOA->AFR[1] = (GPIOA->AFR[1] &~GPIO_AFRH_AFRH7) | 1 << (7 * 4); // PA15
+    // DMA: Tx - Ch4
+    DMA1_Channel4->CPAR = (uint32_t) &USART2->TDR; // periph
+    DMA1_Channel4->CMAR = (uint32_t) tbuf; // mem
+    DMA1_Channel4->CCR |= DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE; // 8bit, mem++, mem->per, transcompl irq
+    // Tx CNDTR set @ each transmission due to data size
+    NVIC_SetPriority(DMA1_Channel4_5_IRQn, 3);
+    NVIC_EnableIRQ(DMA1_Channel4_5_IRQn);
+    NVIC_SetPriority(USART2_IRQn, 0);
+    // setup usart2
+    RCC->APB1ENR |= RCC_APB1ENR_USART2EN; // clock
+    // oversampling by16, 115200bps (fck=48mHz)
+    //USART2_BRR = 0x1a1; // 48000000 / 115200
+    USART2->BRR = 480000 / 1152;
+    USART2->CR3 = USART_CR3_DMAT; // enable DMA Tx
+    USART2->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE; // 1start,8data,nstop; enable Rx,Tx,USART
+    while(!(USART2->ISR & USART_ISR_TC)); // polling idle frame Transmission
+    USART2->ICR |= USART_ICR_TCCF; // clear TC flag
+    USART2->CR1 |= USART_CR1_RXNEIE;
+    NVIC_EnableIRQ(USART2_IRQn);
+// USART1 of main board
+#elif USARTNUM == 1
+    // PA9 - Tx, PA10 - Rx (AF1)
+    GPIOA->MODER = (GPIOA->MODER & ~(GPIO_MODER_MODER9 | GPIO_MODER_MODER10))\
+                | (GPIO_MODER_MODER9_AF | GPIO_MODER_MODER10_AF);
+    GPIOA->AFR[1] = (GPIOA->AFR[1] & ~(GPIO_AFRH_AFRH1 | GPIO_AFRH_AFRH2)) |
+                1 << (1 * 4) | 1 << (2 * 4); // PA9, PA10
+    // USART1 Tx DMA - Channel2 (default value in SYSCFG_CFGR1)
+    DMA1_Channel2->CPAR = (uint32_t) &USART1->TDR; // periph
+    DMA1_Channel2->CMAR = (uint32_t) tbuf; // mem
+    DMA1_Channel2->CCR |= DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_TCIE; // 8bit, mem++, mem->per, transcompl irq
+    // Tx CNDTR set @ each transmission due to data size
+    NVIC_SetPriority(DMA1_Channel2_3_IRQn, 3);
+    NVIC_EnableIRQ(DMA1_Channel2_3_IRQn);
+    NVIC_SetPriority(USART1_IRQn, 0);
+    // setup usart1
+    RCC->APB2ENR |= RCC_APB2ENR_USART1EN;
+    USART1->BRR = 480000 / 1152;
+    USART1->CR3 = USART_CR3_DMAT; // enable DMA Tx
+    USART1->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE; // 1start,8data,nstop; enable Rx,Tx,USART
+    while(!(USART1->ISR & USART_ISR_TC)); // polling idle frame Transmission
+    USART1->ICR |= USART_ICR_TCCF; // clear TC flag
+    USART1->CR1 |= USART_CR1_RXNEIE;
+    NVIC_EnableIRQ(USART1_IRQn);
+#else
+#error "Not implemented"
+#endif
+}
+
+#if USARTNUM == 2
+void usart2_isr(){
+// USART1
+#elif USARTNUM == 1
+void usart1_isr(){
+#else
+#error "Not implemented"
+#endif
+    #ifdef CHECK_TMOUT
+    static uint32_t tmout = 0;
+    #endif
+    if(USARTX->ISR & USART_ISR_RXNE){ // RX not emty - receive next char
+        #ifdef CHECK_TMOUT
+        if(tmout && Tms >= tmout){ // set overflow flag
+            bufovr = 1;
+            datalen[rbufno] = 0;
+        }
+        tmout = Tms + TIMEOUT_MS;
+        if(!tmout) tmout = 1; // prevent 0
+        #endif
+        // read RDR clears flag
+        uint8_t rb = USARTX->RDR;
+        if(datalen[rbufno] < UARTBUFSZ){ // put next char into buf
+            rbuf[rbufno][datalen[rbufno]++] = rb;
+            if(rb == '\n'){ // got newline - line ready
+                linerdy = 1;
+                dlen = datalen[rbufno];
+                recvdata = rbuf[rbufno];
+                // prepare other buffer
+                rbufno = !rbufno;
+                datalen[rbufno] = 0;
+                #ifdef CHECK_TMOUT
+                // clear timeout at line end
+                tmout = 0;
+                #endif
+            }
+        }else{ // buffer overrun
+            bufovr = 1;
+            datalen[rbufno] = 0;
+            #ifdef CHECK_TMOUT
+            tmout = 0;
+            #endif
+        }
+    }
+}
+
+// print 32bit unsigned int
+void printu(uint32_t val){
+    char bufa[11], bufb[10];
+    int l = 0, bpos = 0;
+    if(!val){
+        bufa[0] = '0';
+        l = 1;
+    }else{
+        while(val){
+            bufb[l++] = val % 10 + '0';
+            val /= 10;
+        }
+        int i;
+        bpos += l;
+        for(i = 0; i < l; ++i){
+            bufa[--bpos] = bufb[i];
+        }
+    }
+    while(LINE_BUSY == usart_send_blocking(bufa, l+bpos));
+}
+
+#if USARTNUM == 2
+void dma1_channel4_5_isr(){
+    if(DMA1->ISR & DMA_ISR_TCIF4){ // Tx
+        DMA1->IFCR |= DMA_IFCR_CTCIF4; // clear TC flag
+        txrdy = 1;
+    }
+}
+// USART1
+#elif USARTNUM == 1
+void dma1_channel2_3_isr(){
+    if(DMA1->ISR & DMA_ISR_TCIF2){ // Tx
+        DMA1->IFCR |= DMA_IFCR_CTCIF2; // clear TC flag
+        txrdy = 1;
+    }
+}
+#else
+#error "Not implemented"
+#endif

F0-nolib/canbus/src/usart.h

@@ -0,0 +1,60 @@
+/*
+ * usart.h
+ *
+ * Copyright 2017 Edward V. Emelianoff <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 __USART_H__
+#define __USART_H__
+
+// input and output buffers size
+#define UARTBUFSZ  (64)
+// timeout between data bytes
+#ifndef TIMEOUT_MS
+#define TIMEOUT_MS (1500)
+#endif
+
+// macro for static strings
+#define SEND(str) do{}while(LINE_BUSY == usart_send_blocking(str, sizeof(str)-1))
+
+#ifdef EBUG
+#define MSG(str)  do{SEND(__FILE__ " (L" STR(__LINE__) "): " str);}while(0)
+#else
+#define MSG(str)
+#endif
+
+typedef enum{
+    ALL_OK,
+    LINE_BUSY,
+    STR_TOO_LONG
+} TXstatus;
+
+#define usartrx()  (linerdy)
+#define usartovr() (bufovr)
+
+extern volatile int linerdy, bufovr, txrdy;
+
+void usart_setup();
+int usart_getline(char **line);
+TXstatus usart_send(const char *str, int len);
+TXstatus usart_send_blocking(const char *str, int len);
+void newline();
+void usart_putchar(const char ch);
+void printu(uint32_t val);
+
+#endif // __USART_H__