add basic LED+USART example

This commit is contained in:
King Kévin 2016-01-17 14:54:54 +01:00
parent ebd0bc03b2
commit f0d2933ff8
4 changed files with 289 additions and 0 deletions

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/* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */
/* this library handles the USART
* it uses the TX and RX pins (depending on which USART is used)
*/
/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdio.h> // standard I/O facilities
#include <stdlib.h> // general utilities
/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/stm32/usart.h> // universal synchronous asynchronous receiver transmitter library
#include <libopencm3/cm3/nvic.h> // interrupt handler
#include "usart.h" // USART header and definitions
/* input and output ring buffer, indexes, and available memory */
uint8_t rx_buffer[USART_BUFFER] = {0};
volatile uint8_t rx_i = 0;
volatile uint8_t rx_used = 0;
uint8_t tx_buffer[USART_BUFFER] = {0};
volatile uint8_t tx_i = 0;
volatile uint8_t tx_used = 0;
/* show the user how much data received over USART is ready */
volatile uint8_t usart_received = 0; // same as rx_used, but since the user can write this variable we don't rely on it
/* setup USART port */
void usart_setup(void)
{
rcc_periph_clock_enable(USART_RCC); // enable USART1 clock
gpio_set_mode(USART_PORT, GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, USART_PIN_TX); // setup GPIO pin USART transmit
gpio_set_mode(USART_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, USART_PIN_RX); // setup GPIO pin USART receive
/* setup UART parameters */
usart_set_baudrate(USART, 115200);
usart_set_databits(USART, 8);
usart_set_stopbits(USART, USART_STOPBITS_1);
usart_set_mode(USART, USART_MODE_TX_RX);
usart_set_parity(USART, USART_PARITY_NONE);
usart_set_flow_control(USART, USART_FLOWCONTROL_NONE);
nvic_enable_irq(USART_IRQ); // enable the USART2 interrupt
usart_enable(USART); // enable USART
/* reset buffer states */
tx_i = 0;
tx_used = 0;
rx_i = 0;
rx_used = 0;
usart_received = 0;
}
/* put character on USART (blocking) */
void usart_putchar_blocking(char c)
{
if (c == '\n') { // add carrier return before line feed. this is recommended for most UART terminals
usart_putchar_blocking('\r'); // a second carrier return doesn't influence the terminal
}
usart_flush(); // empty buffer first
usart_send_blocking(USART, c); // send character
}
/* ensure all data has been transmitted (blocking) */
void usart_flush(void)
{
while (tx_used) { // idle until buffer is empty
__asm__("wfi"); // sleep until interrupt
}
usart_wait_send_ready(USART); // wait until transmit register is empty (transmission might not be complete)
}
/* get character from USART (blocking) */
char usart_getchar(void)
{
while (!rx_used) { // idle until data is available
__asm__("wfi"); // sleep until interrupt;
}
char to_return = rx_buffer[rx_i]; // get the next available character
rx_i = (rx_i+1)%sizeof(rx_buffer); // update used buffer
rx_used--; // update used buffer
usart_received = rx_used; // update available data
return to_return;
}
/* put character on USART stream (non-blocking using a buffer) */
void usart_putchar_nonblocking(char c)
{
while (tx_used>=sizeof(tx_buffer)) { // idle until buffer has some space
__asm__("wfi");
}
tx_buffer[(tx_i+tx_used)%sizeof(tx_buffer)] = c; // put character in buffer
tx_used++; // update used buffer
usart_enable_tx_interrupt(USART); // enable transmit interrupt
}
#if (USART==USART1)
void usart1_isr(void)
#elif (USART==USART2)
void usart2_isr(void)
#elif (USART==USART3)
void usart3_isr(void)
#endif
{ // USART interrupt
if (usart_get_interrupt_source(USART, USART_SR_TXE)) { // data has been transmitted
if (!tx_used) { // no data in the buffer to transmit
usart_disable_tx_interrupt(USART); // disable transmit interrupt
} else {
usart_send(USART,tx_buffer[tx_i]); // put data in transmit register
tx_i = (tx_i+1)%sizeof(rx_buffer); // update location on buffer
tx_used--; // update used size
}
}
if (usart_get_interrupt_source(USART, USART_SR_RXNE)) { // data has been received
// only save data if there is space in the buffer
if (rx_used>=sizeof(rx_buffer)) {
usart_recv(USART); // read to clear interrupt
} else {
rx_buffer[(rx_i+rx_used)%sizeof(rx_buffer)] = usart_recv(USART); // put character in buffer
rx_used++; // update used buffer
usart_received = rx_used; // update available data
}
}
}

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/* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */
/* This library handles the USART */
/* which USART to use */
#define USART USART1
#define USART_RCC RCC_USART1
#define USART_IRQ NVIC_USART1_IRQ
#define USART_PORT GPIOA
#define USART_PIN_TX GPIO_USART1_TX
#define USART_PIN_RX GPIO_USART1_RX
/* serial baudrate, in bits per second (with 8N1 8 bits, no parity bit, 1 stop bit settings) */
#define BAUD 115200
/* USART RX and TX buffer sizes */
#define USART_BUFFER 64
/* show the user how much received is available */
extern volatile uint8_t usart_received;
/* setup USART port */
void usart_setup(void);
/* put character on USART (blocking) */
void usart_putchar_blocking(char c);
/* ensure all data has been transmitted (blocking) */
void usart_flush(void);
/* get character from USART (blocking) */
char usart_getchar(void);
/* put character on USART (non-blocking until buffer is full) */
void usart_putchar_nonblocking(char c);

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/* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */
/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdio.h> // standard I/O facilities
#include <stdlib.h> // standard utilities
#include <unistd.h> // standard streams
#include <errno.h> // error number utilities
/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/cm3/scb.h> // vector table definition
/* own libraries */
#include "main.h" // board definitions
#include "usart.h" // USART utilities
/* default output (i.e. for printf) */
int _write(int file, char *ptr, int len)
{
int i;
if (file == STDOUT_FILENO || file == STDERR_FILENO) {
for (i = 0; i < len; i++) {
if (ptr[i] == '\n') { // add carrier return before line feed. this is recommended for most UART terminals
usart_putchar_nonblocking('\r'); // a second line feed doesn't break the display
}
usart_putchar_nonblocking(ptr[i]); // send byte over USART
}
return i;
}
errno = EIO;
return -1;
}
static void clock_setup(void)
{
rcc_clock_setup_in_hse_8mhz_out_72mhz(); // use 8 MHz high speed external clock to generate 72 MHz internal clock
rcc_periph_clock_enable(LED_RCC); //enable clock for LED
}
static void gpio_setup(void)
{
/* set LED pin to 'output push-pull' */
gpio_set_mode(LED_PORT, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, LED_PIN);
}
int main(void)
{
int i, c = 0;
SCB_VTOR = (uint32_t) 0x08002000; // relocate vector table because of the bootloader
clock_setup();
gpio_setup();
usart_setup();
setbuf(stdout, NULL); // set standard out buffer to NULL to immediately print
setbuf(stderr, NULL); // set standard error buffer to NULL to immediately print
/* blink the LED with every transmitted character */
while (1) {
gpio_toggle(LED_PORT, LED_PIN); /* LED on/off */
printf("%c",c+'0');
c = (c == 9) ? 0 : c + 1; /* increment c */
for (i = 0; i < 8000000; i++) /* wait a bit */
__asm__("nop");
}
return 0;
}

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/* 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 3 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, see <http://www.gnu.org/licenses/>.
*
*/
/* Copyright (c) 2016 King Kévin <kingkevin@cuvoodoo.info> */
/* LED is on pin 11/PA1 */
#define LED_PORT GPIOA
#define LED_PIN GPIO1
#define LED_RCC RCC_GPIOA
/* default output (i.e. for printf) */
int _write(int file, char *ptr, int len);