120 lines
4.9 KiB
C
120 lines
4.9 KiB
C
/* 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/>.
|
|
*
|
|
*/
|
|
/** library for UART communication (code)
|
|
* @file uart.c
|
|
* @author King Kévin <kingkevin@cuvoodoo.info>
|
|
* @date 2016-2018
|
|
* @note peripherals used: USART @ref uart
|
|
*/
|
|
|
|
/* 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 <libopencmsis/core_cm3.h> // Cortex M3 utilities
|
|
|
|
#include "uart.h" // UART header and definitions
|
|
#include "global.h" // common methods
|
|
|
|
/** @defgroup uart USART peripheral used for UART communication
|
|
* @{
|
|
*/
|
|
#define UART_ID 1 /**< USART peripheral */
|
|
/** @} */
|
|
|
|
#define UART_BAUDRATE 115200 /**< serial baudrate, in bits per second (with 8N1 8 bits, no parity bit, 1 stop bit settings) */
|
|
|
|
/* output ring buffer, indexes, and available memory */
|
|
static volatile uint8_t tx_buffer[64] = {0}; /**< ring buffer for data to transmit */
|
|
static volatile uint8_t tx_i = 0; /**< current position of transmitted data */
|
|
static volatile uint8_t tx_used = 0; /**< how much data needs to be transmitted */
|
|
|
|
void uart_setup(void)
|
|
{
|
|
/* enable UART I/O peripheral */
|
|
rcc_periph_clock_enable(RCC_USART_PORT(UART_ID)); // enable clock for UART port peripheral
|
|
rcc_periph_clock_enable(RCC_USART(UART_ID)); // enable clock for UART peripheral
|
|
rcc_periph_clock_enable(RCC_AFIO); // enable pin alternate function (UART)
|
|
gpio_set_mode(USART_TX_PORT(UART_ID), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, USART_TX_PIN(UART_ID)); // setup GPIO pin UART transmit
|
|
gpio_set_mode(USART_RX_PORT(UART_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, USART_RX_PIN(UART_ID)); // setup GPIO pin UART receive
|
|
gpio_set(USART_RX_PORT(UART_ID), USART_RX_PIN(UART_ID)); // pull up to avoid noise when not connected
|
|
|
|
/* setup UART parameters */
|
|
usart_set_baudrate(USART(UART_ID), UART_BAUDRATE);
|
|
usart_set_databits(USART(UART_ID), 8);
|
|
usart_set_stopbits(USART(UART_ID), USART_STOPBITS_1);
|
|
usart_set_mode(USART(UART_ID), USART_MODE_TX_RX);
|
|
usart_set_parity(USART(UART_ID), USART_PARITY_NONE);
|
|
usart_set_flow_control(USART(UART_ID), USART_FLOWCONTROL_NONE);
|
|
|
|
nvic_enable_irq(USART_IRQ(UART_ID)); // enable the UART interrupt
|
|
usart_enable_rx_interrupt(USART(UART_ID)); // enable receive interrupt
|
|
usart_enable(USART(UART_ID)); // enable UART
|
|
|
|
/* reset buffer states */
|
|
tx_i = 0;
|
|
tx_used = 0;
|
|
}
|
|
|
|
void uart_putchar_blocking(char c)
|
|
{
|
|
uart_flush(); // empty buffer first
|
|
usart_send_blocking(USART(UART_ID), c); // send character
|
|
}
|
|
|
|
void uart_flush(void)
|
|
{
|
|
while (tx_used) { // idle until buffer is empty
|
|
__WFI(); // sleep until interrupt
|
|
}
|
|
usart_wait_send_ready(USART(UART_ID)); // wait until transmit register is empty (transmission might not be complete)
|
|
}
|
|
|
|
void uart_putchar_nonblocking(char c)
|
|
{
|
|
while (tx_used>=LENGTH(tx_buffer)) { // idle until buffer has some space
|
|
usart_enable_tx_interrupt(USART(UART_ID)); // enable transmit interrupt
|
|
// don't go to sleep since this might prevent an interrupt
|
|
}
|
|
usart_disable_tx_interrupt(USART(UART_ID)); // disable transmit interrupt to prevent index corruption
|
|
tx_buffer[(tx_i+tx_used)%LENGTH(tx_buffer)] = c; // put character in buffer
|
|
tx_used++; // update used buffer
|
|
usart_enable_tx_interrupt(USART(UART_ID)); // enable transmit interrupt
|
|
}
|
|
|
|
/** UART interrupt service routine called when data has been transmitted or received */
|
|
void USART_ISR(UART_ID)(void)
|
|
{
|
|
if (usart_get_flag(USART(UART_ID), USART_SR_TXE)) { // data has been transmitted
|
|
if (!tx_used) { // no data in the buffer to transmit
|
|
usart_disable_tx_interrupt(USART(UART_ID)); // disable transmit interrupt
|
|
} else {
|
|
usart_send(USART(UART_ID),tx_buffer[tx_i]); // put data in transmit register
|
|
tx_i = (tx_i+1)%LENGTH(tx_buffer); // update location on buffer
|
|
tx_used--; // update used size
|
|
}
|
|
}
|
|
while (usart_get_flag(USART(UART_ID), USART_SR_RXNE)) { // data has been received (repeat while receiving)
|
|
char c = usart_recv(USART(UART_ID)); // save character and free UART buffer
|
|
user_input_store(c); // store data
|
|
}
|
|
}
|