rt-thread/bsp/stm32/stm32mp157a-st-discovery/board/ports/drv_rs485.c

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/*
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* Copyright (c) 2006-2021, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2020-10-24 thread-liu first version
*/
#include <board.h>
#include "drv_rs485.h"
#ifdef BSP_USING_RS485
#define RS485_OUT rt_pin_write(BSP_RS485_RTS_PIN, PIN_HIGH)
#define RS485_IN rt_pin_write(BSP_RS485_RTS_PIN, PIN_LOW)
static rt_device_t serial = {0};
static struct rt_semaphore rx_sem = {0};
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/* uart send data callback function */
static rt_err_t rs485_output(rt_device_t dev, void * buffer)
{
return RT_EOK;
}
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/* uart receive data callback function */
static rt_err_t rs485_input(rt_device_t dev, rt_size_t size)
{
rt_sem_release(&rx_sem);
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return RT_EOK;
}
/* send string */
int rs485_send_data(char *tbuf, rt_uint16_t t_len)
{
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/* change rs485 mode */
RS485_OUT;
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/* send data */
rt_device_write(serial, 0, tbuf, t_len);
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/* change rs485 mode */
RS485_IN;
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return RT_EOK;
}
static void rs485_thread_entry(void *parameter)
{
char ch;
while (1)
{
/* A byte of data is read from a serial port, and if it is not read, it waits for the received semaphore */
while (rt_device_read(serial, -1, &ch, 1) != 1)
{
rt_sem_take(&rx_sem, RT_WAITING_FOREVER);
}
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/* The data read through the serial port output dislocation */
ch = ch + 1;
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/* send char */
rs485_send_data(&ch, 1);
}
}
/* rs485 rts pin init */
static int rs485_init(void)
{
/* find uart device */
serial = rt_device_find(RS485_UART_DEVICE_NAME);
if (!serial)
{
rt_kprintf("find %s failed!\n", RS485_UART_DEVICE_NAME);
return RT_ERROR;
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}
rt_device_open(serial, RT_DEVICE_FLAG_INT_RX);
/* set receive data callback function */
rt_device_set_rx_indicate(serial, rs485_input);
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/* set the send completion callback function */
rt_device_set_tx_complete(serial, rs485_output);
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rt_pin_mode(BSP_RS485_RTS_PIN, PIN_MODE_OUTPUT);
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RS485_IN;
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rt_sem_init(&rx_sem, "rx_sem", 0, RT_IPC_FLAG_FIFO);
/* create rs485 thread */
rt_thread_t thread = rt_thread_create("rs485", rs485_thread_entry, RT_NULL, 1024, 25, 10);
if (thread != RT_NULL)
{
rt_thread_startup(thread);
}
else
{
return RT_ERROR;
}
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return RT_EOK;
}
INIT_DEVICE_EXPORT(rs485_init);
#endif /* bsp_using_RS485 */