58 lines
1.3 KiB
C
58 lines
1.3 KiB
C
#include "usart.h"
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#include "os/delay.h"
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#include <stddef.h>
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#include <stdint.h>
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#define USART_SR_TXE (1 << 7)
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typedef struct uart_s {
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uint32_t USART_SR;
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uint32_t USART_DR;
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uint32_t USART_BRR;
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uint32_t USART_CR1;
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uint32_t USART_CR2;
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uint32_t USART_CR3;
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uint32_t USART_GTPR;
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} uart_c;
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volatile uart_c *const USART1 = (uart_c *)0x40011000;
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static uint32_t usart_tx_ready(void) {
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return (USART1->USART_SR & USART_SR_TXE) >> 7;
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}
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uint32_t usart_tx_write(const uint8_t *data_bytes, uint32_t n_bytes) {
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if (data_bytes == NULL) return USART_TX_ERROR;
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for (int i = 0; i < n_bytes; i++) {
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unsigned int timeout = TIMEOUT;
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while (!usart_tx_ready()) {
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delay_ms(1);
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timeout--;
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if (timeout == 0) return USART_TX_BUSY;
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}
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USART1->USART_DR = *data_bytes;
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data_bytes++;
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}
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return USART_TX_COMPLETE;
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}
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uint32_t usart_tx_write_string(const uint8_t *data_bytes) {
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if (data_bytes == NULL) return USART_TX_ERROR;
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while (*data_bytes != '\0') {
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unsigned int timeout = TIMEOUT;
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while (!usart_tx_ready()) {
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delay_ms(1);
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timeout--;
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if (timeout == 0) return USART_TX_BUSY;
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}
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USART1->USART_DR = *data_bytes;
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data_bytes++;
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}
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return USART_TX_COMPLETE;
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}
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