add usart example for STM32F042-nucleo

F0-nolib/README

@@ -1 +0,0 @@
-This directory contains examples for F0 without any library

F0-nolib/uart_blink_dma/Makefile

@@ -0,0 +1,137 @@
+BINARY		= uartblink
+BOOTPORT	?= /dev/ttyUSB0
+BOOTSPEED	?= 115200
+# MCU FAMILY
+FAMILY		= F0
+# MCU code
+MCU			= F030x4
+DEFS		= -DEBUG
+# change this linking script depending on particular MCU model,
+# for example, if you have STM32F103VBT6, you should write:
+LDSCRIPT	= ld/stm32f030f.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
+PREFIX		?= /opt/bin/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
+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 -Werror -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
+	@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)
+
+.PHONY: clean flash boot

F0-nolib/uart_blink_dma/Readme.md

@@ -0,0 +1,7 @@
+Code for STM32F030F4 chinese board
+USART Rx by interrupts, Tx by DMA
+- Toggle onboard green LED once per second.
+- Echo received by USART1 data (not more than 64 bytes including '\n') on B115200:
+	- if PA6 not connected to ground echo text directly
+	- otherwice echo it reversly
+- Light up LED on PA5 (opendrain) when receive data and turn it off when send.

F0-nolib/uart_blink_dma/ld/stm32f030f.ld

@@ -0,0 +1,12 @@
+/* Linker script for STM32F030f4, 16K flash, 4K RAM. */
+
+/* Define memory regions. */
+MEMORY
+{
+    rom   (rx) : ORIGIN = 0x08000000, LENGTH = 16K
+    ram  (rwx) : ORIGIN = 0x20000000, LENGTH = 4K
+}
+
+/* Include the common ld script. */
+INCLUDE stm32f0.ld
+

F0-nolib/uart_blink_dma/main.c

@@ -0,0 +1,91 @@
+/*
+ * 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 "stm32f0.h"
+#include "usart.h"
+
+volatile uint32_t Tms = 0;
+
+/* Called when systick fires */
+void sys_tick_handler(void){
+    ++Tms;
+}
+
+static void gpio_setup(void){
+    /* Enable clocks to the GPIO subsystems (A&B) */
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
+    /* Set green leds (PA5 & PA5) as output */
+    GPIOA->MODER = GPIO_MODER_MODER4_O | GPIO_MODER_MODER5_O;
+    GPIOA->OTYPER = 1 << 5; // PA5 - opendrain, PA4 - pushpull
+    /* PA6 - switch blink rate (pullup input) */
+    GPIOA->PUPDR = GPIO_PUPDR_PUPDR6_0;
+}
+
+/**
+ * reverce line
+ */
+char *rline(char *in, int L){
+    static char out[UARTBUFSZ];
+    if(L > UARTBUFSZ - 1) return in;
+    char *optr = out, *iptr = &in[L-1];
+    for(; L > 0; --L) *optr++ = *iptr--;
+    *optr = '\n';
+    return out;
+}
+
+int main(void){
+    uint32_t lastT = 0;
+    int L = 0, dummyctr = 0;
+    uint32_t ostctr = 0;
+    char *txt;
+    sysreset();
+    SysTick_Config(6000, 1);
+    gpio_setup();
+    USART1_config();
+    //StartHSE();
+    pin_set(GPIOA, 1<<5); // clear extern LED
+    /* Do nothing in main loop */
+    while (1){
+        if(lastT > Tms || Tms - lastT > 499){
+            pin_toggle(GPIOA, 1<<4); // blink by onboard LED once per second
+            lastT = Tms;
+        }
+        if(usart1rx()){ // usart1 received data, store in in buffer
+            L = usart1_getline(&txt);
+            if(!pin_read(GPIOA, 1<<6)){ // there's a jumper: reverse string
+                txt = rline(txt, L);
+            }
+            pin_clear(GPIOA, 1<<5); // set extern LED
+        }
+        if(L){ // text waits for sending
+            if(ALL_OK == usart1_send(txt, L)){
+                L = 0;
+                pin_set(GPIOA, 1<<5); // clear extern LED
+            }
+        }else if(ostctr != Tms){
+            ostctr = Tms;
+            if(++dummyctr > 5000){ // once per 5 seconds
+                dummyctr = 0;
+                if(ALL_OK != usart1_send("Dummy text\n", 11)) pin_toggle(GPIOA, 1<<5);
+            }
+        }
+    }
+}

F0-nolib/uart_blink_dma/usart.c

@@ -0,0 +1,154 @@
+/*
+ * usart.c
+ *
+ * Copyright 2017 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 "usart.h"
+#include <string.h> // memcpy
+
+extern volatile uint32_t Tms;
+
+static int datalen[2] = {0,0}; // received data line length (including '\n')
+
+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
+;
+
+static int  rbufno = 0; // current rbuf number
+static char rbuf[2][UARTBUFSZ], tbuf[UARTBUFSZ]; // receive & transmit buffers
+static char *recvdata = NULL;
+
+void USART1_config(){
+    /* Enable the peripheral clock of GPIOA */
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
+    /* GPIO configuration for USART1 signals */
+    /* (1) Select AF mode (10) on PA9 and PA10 */
+    /* (2) AF1 for USART1 signals */
+    GPIOA->MODER = (GPIOA->MODER & ~(GPIO_MODER_MODER9|GPIO_MODER_MODER10))\
+                | (GPIO_MODER_MODER9_1 | GPIO_MODER_MODER10_1); /* (1) */
+    GPIOA->AFR[1] = (GPIOA->AFR[1] &~ (GPIO_AFRH_AFRH1 | GPIO_AFRH_AFRH2))\
+                | (1 << (1 * 4)) | (1 << (2 * 4)); /* (2) */
+    /* Enable the peripheral clock USART1 */
+    RCC->APB2ENR |= RCC_APB2ENR_USART1EN;
+    /* Configure USART1 */
+    /* (1) oversampling by 16, 115200 baud */
+    /* (2) 8 data bit, 1 start bit, 1 stop bit, no parity */
+    USART1->BRR = 480000 / 1152; /* (1) */
+    USART1->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE; /* (2) */
+    /* polling idle frame Transmission */
+    while(!(USART1->ISR & USART_ISR_TC)){}
+    USART1->ICR |= USART_ICR_TCCF; /* clear TC flag */
+    USART1->CR1 |= USART_CR1_RXNEIE; /* enable TC, TXE & RXNE interrupt */
+    RCC->AHBENR |= RCC_AHBENR_DMA1EN;
+    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
+    USART1->CR3 = USART_CR3_DMAT;
+    NVIC_SetPriority(DMA1_Channel2_3_IRQn, 3);
+    NVIC_EnableIRQ(DMA1_Channel2_3_IRQn);
+    /* Configure IT */
+    /* (3) Set priority for USART1_IRQn */
+    /* (4) Enable USART1_IRQn */
+    NVIC_SetPriority(USART1_IRQn, 0); /* (3) */
+    NVIC_EnableIRQ(USART1_IRQn); /* (4) */
+}
+
+void usart1_isr(){
+    #ifdef CHECK_TMOUT
+    static uint32_t tmout = 0;
+    #endif
+    if(USART1->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 = USART1->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
+        }
+    }
+}
+
+void dma1_channel2_3_isr(){
+    if(DMA1->ISR & DMA_ISR_TCIF2){ // Tx
+        DMA1->IFCR |= DMA_IFCR_CTCIF2; // clear TC flag
+        txrdy = 1;
+    }
+}
+
+/**
+ * return length of received data (without trailing zero
+ */
+int usart1_getline(char **line){
+    if(bufovr){
+        bufovr = 0;
+        linerdy = 0;
+        return 0;
+    }
+    *line = recvdata;
+    linerdy = 0;
+    return dlen;
+}
+
+TXstatus usart1_send(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    if(len > UARTBUFSZ) return STR_TOO_LONG;
+    txrdy = 0;
+    DMA1_Channel2->CCR &= ~DMA_CCR_EN;
+    memcpy(tbuf, str, len);
+    DMA1_Channel2->CNDTR = len;
+    DMA1_Channel2->CCR |= DMA_CCR_EN; // start transmission
+    return ALL_OK;
+}
+
+TXstatus usart1_send_blocking(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    int i;
+    for(i = 0; i < len; ++i){
+        USART1->TDR = *str++;
+        while(!(USART1->ISR & USART_ISR_TXE));
+    }
+    txrdy = 1;
+    return ALL_OK;
+}

F0-nolib/uart_blink_dma/usart.h

@@ -0,0 +1,51 @@
+/*
+ * usart.h
+ *
+ * Copyright 2017 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 __USART_H__
+#define __USART_H__
+
+#include "stm32f0.h"
+
+// input and output buffers size
+#define UARTBUFSZ  (64)
+// timeout between data bytes
+#define TIMEOUT_MS (1500)
+// check timeout
+#define CHECK_TMOUT
+
+typedef enum{
+    ALL_OK,
+    LINE_BUSY,
+    STR_TOO_LONG
+} TXstatus;
+
+#define usart1rx()  (linerdy)
+#define usart1ovr() (bufovr)
+
+extern int linerdy, bufovr, txrdy;
+
+void USART1_config();
+int usart1_getline(char **line);
+TXstatus usart1_send(const char *str, int len);
+TXstatus usart1_send_blocking(const char *str, int len);
+
+
+#endif // __USART_H__

F0-nolib/uart_nucleo/Makefile

@@ -0,0 +1,137 @@
+BINARY		= usart
+BOOTPORT	?= /dev/ttyUSB0
+BOOTSPEED	?= 115200
+# MCU FAMILY
+FAMILY		= F0
+# MCU code
+MCU			= F042x6
+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
+PREFIX		?= /opt/bin/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
+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 -Werror -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
+	@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)
+
+.PHONY: clean flash boot

F0-nolib/uart_nucleo/Readme

@@ -0,0 +1,9 @@
+This is a simple USART over DMA application with software end of string control.
+Speed 115200. Received string echoes back.
+run
+DEFS=-DCHECK_TMOUT make
+to add timeout 1.5s for each letter
+
+DEFS="-DCHECK_TMOUT -DTIMEOUT_MS=xx" make
+to make another timeout
+

F0-nolib/uart_nucleo/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/uart_nucleo/main.c

@@ -0,0 +1,95 @@
+/*
+ * 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 "stm32f0.h"
+#include "usart.h"
+
+volatile uint32_t Tms = 0;
+
+/* Called when systick fires */
+void sys_tick_handler(void){
+    ++Tms;
+}
+
+static void gpio_setup(void){
+    // Set green led (PB3) as output
+    RCC->AHBENR |= RCC_AHBENR_GPIOBEN;
+    GPIOB->MODER = GPIO_MODER_MODER3_O;
+}
+
+void printi(int16_t val){
+    char buf[6], rbuf[5];
+    int l = 0, bpos = 0;
+    if(!val){
+        buf[0] = '0';
+        l = 1;
+    }else{
+        if(val < 0){
+            buf[0] = '-';
+            bpos = 1;
+            val = -val;
+        }
+        while(val){
+            rbuf[l++] = val % 10 + '0';
+            val /= 10;
+        }
+        int i;
+        bpos += l;
+        for(i = 0; i < l; ++i){
+            buf[--bpos] = rbuf[i];
+        }
+    }
+    while(ALL_OK != usart2_send_blocking(buf, l+bpos));
+    while(ALL_OK != usart2_send_blocking("\n", 1));
+}
+
+int main(void){
+    uint32_t lastT = 0, dctr = 0;
+    int16_t L = 0;
+    char *txt;
+    sysreset();
+    SysTick_Config(6000, 1);
+    gpio_setup();
+    usart2_setup();
+
+    while (1){
+        if(lastT > Tms || Tms - lastT > 499){
+            pin_toggle(GPIOB, 1<<3); // blink by onboard LED once per second
+            lastT = Tms;
+        }
+        if(usart2rx()){ // usart1 received data, store in in buffer
+            L = usart2_getline(&txt);
+            printi(L);
+            // do something with received data
+        }
+        if(L){ // text waits for sending
+            if(ALL_OK == usart2_send(txt, L)){
+                L = 0;
+            }
+        }
+        if(dctr > Tms || Tms - dctr > 4999){// once per 5 seconds
+            dctr = Tms;
+            while(ALL_OK != usart2_send_blocking("Dummy text\n", 11));
+        }
+    }
+    return 0;
+}
+

F0-nolib/uart_nucleo/usart.c

@@ -0,0 +1,152 @@
+/*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 "usart.h"
+#include <string.h>
+
+extern volatile uint32_t Tms;
+static int datalen[2] = {0,0}; // received data line length (including '\n')
+
+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 usart2_getline(char **line){
+    if(bufovr){
+        bufovr = 0;
+        linerdy = 0;
+        return 0;
+    }
+    *line = recvdata;
+    linerdy = 0;
+    return dlen;
+}
+
+TXstatus usart2_send(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    if(len > UARTBUFSZ) return STR_TOO_LONG;
+    txrdy = 0;
+    memcpy(tbuf, str, len);
+    DMA1_Channel4->CCR &= ~DMA_CCR_EN;
+    DMA1_Channel4->CNDTR = len;
+    DMA1_Channel4->CCR |= DMA_CCR_EN; // start transmission
+    return ALL_OK;
+}
+
+TXstatus usart2_send_blocking(const char *str, int len){
+    if(!txrdy) return LINE_BUSY;
+    int i;
+    bufovr = 0;
+    for(i = 0; i < len; ++i){
+        USART2->TDR = *str++;
+        while(!(USART2->ISR & USART_ISR_TXE));
+    }
+    txrdy = 1;
+    return ALL_OK;
+}
+
+
+// Nucleo's USART2 connected to VCP proxy of st-link
+void usart2_setup(){
+    // setup pins: PA2 (Tx - AF1), PA15 (Rx - AF1)
+    RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_DMAEN;
+    // AF mode (AF1)
+    GPIOA->MODER = (GPIOA->MODER & ~(GPIO_MODER_MODER2|GPIO_MODER_MODER15))\
+                | (GPIO_MODER_MODER2_1 | GPIO_MODER_MODER15_1);
+    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);
+}
+
+
+void dma1_channel4_5_isr(){
+    if(DMA1->ISR & DMA_ISR_TCIF4){ // Tx
+        DMA1->IFCR |= DMA_IFCR_CTCIF4; // clear TC flag
+        txrdy = 1;
+    }
+}
+
+void usart2_isr(){
+    #ifdef CHECK_TMOUT
+    static uint32_t tmout = 0;
+    #endif
+    if(USART2->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 = USART2->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
+        }
+    }
+}

F0-nolib/uart_nucleo/usart.h

@@ -0,0 +1,48 @@
+/*
+ * 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
+
+typedef enum{
+    ALL_OK,
+    LINE_BUSY,
+    STR_TOO_LONG
+} TXstatus;
+
+#define usart2rx()  (linerdy)
+#define usart2ovr() (bufovr)
+
+extern int linerdy, bufovr, txrdy;
+
+void usart2_setup();
+int usart2_getline(char **line);
+TXstatus usart2_send(const char *str, int len);
+TXstatus usart2_send_blocking(const char *str, int len);
+
+#endif // __USART_H__