/*
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* ds18b20.c
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*
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* Created on: 2021年8月17日
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* Author: Think
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*/
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#include "main.h"
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#include "miscdev.h"
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typedef struct w1_gpio_s
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{
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GPIO_TypeDef *group;
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uint16_t pin;
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} w1_gpio_t;
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static w1_gpio_t W1Dat = /* IO pin connected to PA12 */
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{
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.group = GPIOA,
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.pin = GPIO_PIN_12,
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};
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#define W1DQ_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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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH; \
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HAL_GPIO_Init(W1Dat.group, &GPIO_InitStruct); \
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}
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#define W1DQ_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.Pull = GPIO_NOPULL; \
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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH; \
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HAL_GPIO_Init(W1Dat.group, &GPIO_InitStruct); \
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}
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#define W1DQ_Write(x) HAL_GPIO_WritePin(W1Dat.group, W1Dat.pin, \
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(x==1)?GPIO_PIN_SET:GPIO_PIN_RESET)
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#define W1DQ_Read() HAL_GPIO_ReadPin(W1Dat.group, W1Dat.pin)
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/* Master issues reset pulse and DS18B20s respond with presence pulse */
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uint8_t ds18b20_reset(void)
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{
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uint8_t rv = 0;
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uint8_t retry;
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/* Setup W1 DQ pin as output and high level*/
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W1DQ_Output();
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W1DQ_Write(1);
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delay_us(2);
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/* Reset pulse by pulling the DQ pin low >=480us */
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W1DQ_Write(0);
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delay_us(480);
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/* Master releases bus to high. When DS18B20 detects this rising edge, it waits 15µs to 60µs */
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W1DQ_Write(1);
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delay_us(60);
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/* Then DS18B20 transmits a presence pulse by pulling the W1 bus low for 60µs to 240µs */
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while( W1DQ_Read() && 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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rv = 1;
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delay_us(240);
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/* Master Rx time must >= 480us */
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W1DQ_Output();
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W1DQ_Write(1);
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delay_us(240);
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return rv;
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}
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void ds18b20_write(uint8_t byte)
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{
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uint8_t i = 0;
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W1DQ_Output();
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for(i=0; i<8; i++)
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{
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/* Write 1: pull low <= 15us, Write 0: pull low 15~60us*/
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W1DQ_Write(0);
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delay_us(10);
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/* DS18B20 bit sent by LSB (lower bit first) */
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if( byte & 0x1 )
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W1DQ_Write(1);
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else
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W1DQ_Write(0);
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/* Write 1/0 slot both >= 60us, hold the level for 60us */
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delay_us(60);
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/* Release W1 bus to high */
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W1DQ_Write(1);
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delay_us(2);
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/* Prepare for next bit */
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byte >>= 1;
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}
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}
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uint8_t ds18b20_read(void)
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{
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uint8_t i = 0;
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uint8_t byte = 0;
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for(i=0; i<8; i++)
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{
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/* Read time slot is initiated by master pulling the W1 bus
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* low for minimum of 1µs and then releasing the bus */
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W1DQ_Output();
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W1DQ_Write(0);
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delay_us(2);
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W1DQ_Write(1);
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delay_us(2);
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/* After master initiates read time slot, DS18B20 will begin
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* transmitting a 1 or 0 on bus */
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W1DQ_Input();
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/* DS18B20 bit sent by LSB (lower bit first) */
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if( W1DQ_Read() )
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{
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byte |= 1<<i;
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}
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/* Read slot for >= 60us */
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delay_us(60);
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/* Release W1 bus to high */
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W1DQ_Output();
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W1DQ_Write(1);
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delay_us(2);
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}
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return byte;
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}
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static inline int ds18b20_start_convert(void)
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{
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/* Master issues reset pulse and DS18B20s respond with presence pulse */
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if( 0 != ds18b20_reset() )
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return -1;
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/* Master issues Skip ROM command */
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ds18b20_write(0xCC);
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/* Master issues Convert T command. */
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ds18b20_write(0x44);
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return 0;
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}
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static inline int ds18b20_start_read(uint8_t *buf, int bytes)
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{
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/* Master issues reset pulse and DS18B20s respond with presence pulse */
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if( 0 != ds18b20_reset() )
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return -1;
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/* Master issues Skip ROM command */
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ds18b20_write(0xCC);
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/* Master issues Read Scratchpad command. */
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ds18b20_write(0xBE);
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buf[0] = ds18b20_read(); /* Temperature LSB */
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buf[1] = ds18b20_read(); /* Temperature MSB */
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/*Don't care followed 7 bytes data */
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return 0;
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}
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int ds18b20_sample(float *temperature)
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{
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uint8_t byte[2];
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uint8_t sign;
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uint16_t temp;
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static uint8_t firstin = 1;
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if( !temperature )
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return -1;
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if( 0 != ds18b20_start_convert() )
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return -2;
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/* First sample need 750ms delay */
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if( firstin )
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{
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HAL_Delay(750);
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firstin = 0;
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}
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if( 0 != ds18b20_start_read(byte, 2) )
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return -3;
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/* Temperature byte[0] is LSB, byte[1] is MSB, total 16 bit:
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* Byte[0]: bit[3:0]: decimal bits, bit[7:4]: integer bits
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* bYTE[1]: bit[2:0]: integer bits, bit[7:3]: sign bits
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*/
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if( byte[1]> 0x7 ) /* bit[7:3] is 1 */
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{
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temp = ~(byte[1]<<8|byte[0]) + 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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temp = byte[1]<<8 | byte[0];
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}
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/* byte[1]的低三位和byte[0]的高四位组成温度值的整数部分,
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* 而byte[0]的低四位为小数精度部分,且精度系数为0.0625 */
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*temperature = (temp>>4) + (temp&0xF)*0.0625 ;
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if( !sign )
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{
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*temperature = -*temperature;
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}
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return 0;
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}
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