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標題: STM32用RTS引腳來自動驅動RS485的接收 [打印本頁]

作者: xhaity 時間: 2021-2-5 20:27
標題: STM32用RTS引腳來自動驅動RS485的接收
STM32F有一些型號,可以直接驅動RS485的；在網(wǎng)上搜索了好多，沒有現(xiàn)成的實例；好多提問，最佳答案是否定的，不能自動切換，需要用普通IO做RE 和 DE的驅動。本人使用GD32F330 實驗，用RTS引腳實現(xiàn)自動切換；初始化代碼分享出來供參考。這顆MCU和STM32F030和051系列管腳兼容，寄存器兼容。
/*
* File: USART.h
* Author: hai
*
* Created on November 22, 2020, 11:35 PM
*/

#ifndef USART_H
#define       USART_H
#include "gd32f3x0.h"

/* definition for COM 1, connected to USART0 */
#define INVERTERCOM    USART1
#define INVERTERCOM_CLK RCU_USART1

#define INVERTERCOM_TX_PIN  GPIO_PIN_2
#define INVERTERCOM_RX_PIN  GPIO_PIN_3
#define INVERTERCOM_RTS_PIN GPIO_PIN_1

#define INVERTERCOM_GPIO_PORT       GPIOA
#define INVERTERCOM_GPIO_CLK       RCU_GPIOA
#define INVERTERCOM_AF                      GPIO_AF_1
#define INVERTERCOM_BPS             38400U

#ifdef       __cplusplus
extern "C" {
#endif

void com_init(uint32_t COM);

#ifdef       __cplusplus
}
#endif

#endif       /* USART_H */

#include "usart.h"
#include <stdio.h>

void com_init(uint32_t COM)
{
            /* enable GPIO clock */
rcu_periph_clock_enable(INVERTERCOM_GPIO_CLK);
/* enable USART clock */
rcu_periph_clock_enable(INVERTERCOM_CLK);

/* connect port to USARTx_Tx_RTS */
gpio_af_set(INVERTERCOM_GPIO_PORT, INVERTERCOM_AF, INVERTERCOM_RTS_PIN|INVERTERCOM_TX_PIN|INVERTERCOM_RX_PIN);

            /* configure USART Tx as alternate function push-pull */
            gpio_mode_set(INVERTERCOM_GPIO_PORT,GPIO_MODE_AF,GPIO_PUPD_PULLUP,INVERTERCOM_RTS_PIN);
            gpio_output_options_set(INVERTERCOM_GPIO_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_10MHZ,INVERTERCOM_RTS_PIN);

/* configure USART Tx as alternate function push-pull */
gpio_mode_set(INVERTERCOM_GPIO_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP,INVERTERCOM_TX_PIN);
gpio_output_options_set(INVERTERCOM_GPIO_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_10MHZ,INVERTERCOM_TX_PIN);

/* configure USART Rx as alternate function push-pull */
gpio_mode_set(INVERTERCOM_GPIO_PORT, GPIO_MODE_AF, GPIO_PUPD_PULLUP,INVERTERCOM_RX_PIN);
gpio_output_options_set(INVERTERCOM_GPIO_PORT, GPIO_OTYPE_PP, GPIO_OSPEED_10MHZ,INVERTERCOM_RX_PIN);

/* USART configure */
usart_deinit(COM);
usart_baudrate_set(COM,INVERTERCOM_BPS);
            usart_rs485_driver_enable(COM); //驅動使能
            usart_driver_deassertime_config(COM,0x1F);  // DE (驅動使能)信號的置位與第一個字節(jié)的起始位之間的時間間隔0-0x1F
            usart_driver_assertime_config(COM,0x1F); //定義一個發(fā)送信息最后一個字節(jié)的停止位與置低 DE(驅動使能)信號之間的時間間隔
            usart_depolarity_config(COM,USART_DEP_LOW); //DE極性，根據(jù)硬件選擇，這里硬件用三極管反向了
usart_transmit_config(COM, USART_TRANSMIT_ENABLE);
usart_receive_config(COM, USART_RECEIVE_ENABLE);

usart_enable(COM);

}

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