/****************************************************************************
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* Copyright: (C)2021 武汉凌云物网智科实验室 www.iot-yun.com
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* Author: GuoWenxue<guowenxue@gmail.com> QQ: 281143292
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* Description: 凌云IoT Starter IoT Kits开发板 温度传感器DS18B20采样API函数。
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*
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* SHT20温度传感器使用GPIO模拟I2C总线I2C0
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*
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* ChangeLog:
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* 版本号 日期 作者 说明
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* V1.0.0 2021.06.18 GuoWenxue 发布该版本
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****************************************************************************/
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#include <stdio.h>
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#include "stm32f1xx_hal.h"
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#include "tim.h"
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#define W1DQ_Set_Input() \
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{ \
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GPIO_InitTypeDef GPIO_InitStruct = {0}; \
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GPIO_InitStruct.Pin = W1Dat_Pin; \
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GPIO_InitStruct.Mode = GPIO_MODE_INPUT; \
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GPIO_InitStruct.Pull = GPIO_PULLUP; \
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HAL_GPIO_Init(W1Dat_GPIO_Port, &GPIO_InitStruct); \
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}
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#define W1DQ_Set_Output() \
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{ \
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GPIO_InitTypeDef GPIO_InitStruct = {0}; \
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GPIO_InitStruct.Pin = W1Dat_Pin; \
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GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP; \
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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH; \
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GPIO_InitStruct.Pull = GPIO_PULLUP; \
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HAL_GPIO_Init(W1Dat_GPIO_Port, &GPIO_InitStruct); \
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}
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#define HIGH 1
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#define LOW 0
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#define W1DQ_WritePin(N) HAL_GPIO_WritePin(W1Dat_GPIO_Port, W1Dat_Pin, N!=0?GPIO_PIN_SET:GPIO_PIN_RESET)
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#define W1DQ_ReadPin() HAL_GPIO_ReadPin(W1Dat_GPIO_Port, W1Dat_Pin)
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/* Description: reset DS18B20 and wait for respond signal
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* Return Value: 0: OK -1: No respond signal -2: No reset end signal
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*/
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int ds18b20_init(void)
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{
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uint8_t retry=0;
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int rv = 0;
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/* 1-Wire Data Pin set as output mode */
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W1DQ_Set_Output();
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/* Master send a reset signal of 480~960 µs */
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W1DQ_WritePin(LOW);
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delay_us(750);
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W1DQ_WritePin(HIGH);
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/* When the DS18B20 detects this rising edge, it waits 15~60µs */
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delay_us(15);
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/* Master then releases the bus and goes into receive mode. When the
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* bus is released, the 5kΩ pullup resistor pulls the 1-Wire bus high. */
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W1DQ_Set_Input();
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/* Then DS18B20 will transmits a presence pulse by pulling the 1-Wire bus low for 60~240µs. */
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while ( W1DQ_ReadPin() && retry<240 )
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{
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retry++;
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delay_us(1);
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}
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if(retry>=240)
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{
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rv = -1;
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goto OUT;
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}
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/* Then DS18B20 release bus and resistor will pull-up the bus high for 60~240µs. */
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retry=0;
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while ( !W1DQ_ReadPin() && retry<240 )
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{
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retry++;
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delay_us(1);
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}
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if(retry>=240)
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{
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rv = -2;
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goto OUT;
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}
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OUT:
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if( rv )
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{
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printf("ERROR: DS18B20 check respond signal failure, rv=%d\r\n", rv);
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}
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return rv;
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}
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/* Description: Write a byte data to DS18B20 */
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void w1bus_write_byte(uint8_t byte)
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{
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uint8_t i;
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uint8_t testb;
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/* 1-Wire Data Pin set as output mode */
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W1DQ_Set_Output();
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for(i=1; i<=8; i++)
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{
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testb=byte&0x01; //取最低位
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byte=byte>>1;
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if (testb)
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{
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/* write bit 1: */
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W1DQ_WritePin(LOW);
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delay_us(2);
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W1DQ_WritePin(HIGH);
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delay_us(60);
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}
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else
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{
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/* write bit 0 */
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W1DQ_WritePin(LOW);
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delay_us(60);
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W1DQ_WritePin(HIGH);
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delay_us(2);
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}
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}
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}
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/* Description: Read a bit from DS18B20 */
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uint8_t w1bus_read_bit(void)
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{
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uint8_t bit;
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/* 1-Wire Data Pin set as output mode */
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W1DQ_Set_Output();
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/*Generate read time slot*/
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W1DQ_WritePin(LOW);
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delay_us(2);
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//W1DQ_WritePin(HIGH);
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/*Master must read data from slave in 15us*/
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W1DQ_Set_Input();
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delay_us(8);
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bit = W1DQ_ReadPin() ? 1 : 0;
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delay_us(50);
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return bit;
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}
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/* 从DS18B20读取一个字节 */
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uint8_t w1bus_read_byte(void)
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{
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uint8_t i,j,byte;
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byte=0;
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for(i=1; i<=8; i++)
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{
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j=w1bus_read_bit();
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byte=(j<<7)|(byte>>1);
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}
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return byte;
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}
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int ds18b20_start_convert(void)
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{
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int rv = 0;
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if( 0 != (rv=ds18b20_init()) )
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return rv;
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w1bus_write_byte(0xCC); // Master issues Skip ROM command.
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w1bus_write_byte(0x44); // Master issues Convert T command.
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return 0;
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}
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int ds18b20_start_readreg(void)
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{
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int rv = 0;
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if( 0 != (rv=ds18b20_init()) )
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return rv;
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w1bus_write_byte(0xCC); // Master issues Skip ROM command.
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w1bus_write_byte(0xBE); // Master issues Read Scratchpad command.
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return 0;
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}
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int ds18b20_get_temperature(float *temperature)
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{
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uint8_t sign;
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uint8_t TL,TH;
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uint16_t tmp;
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int rv;
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float temp;
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if( 0 != (rv=ds18b20_start_convert()) )
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return rv;
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if( 0 != (rv=ds18b20_start_readreg()) )
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return rv;
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TL=w1bus_read_byte(); // LSB
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TH=w1bus_read_byte(); // MSB
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printf("DS18B20 Read TH[0x%02x] TH[0x%02x]\r\n", TH, TL);
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if(TH>7) /* 高5位为1，说明温度为负 */
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{
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tmp = ~(TH<<8|TL) + 1; //补码
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sign=0;//温度为负
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}
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else
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{
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sign=1;//温度为正
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tmp = TH<<8 | TL;
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}
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/*12位精度转换时，TH的低三位和TL的高四位组成温度值的整数部分， 而TL的低四位为小数精度部分,并且精度系数为0.0625 */
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temp = (tmp>>4) + (tmp&0xF)*0.0625 ;
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*temperature = sign ? temp : -temp;
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return 0;
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}
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