ukhasnet_ds18bs20/ds18b20.c

#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/cm3/systick.h>
#include <stdint.h>
#include "ds18b20.h"
//#include "delay.h"
#include "misc.h"

// Define GPIO port and pin for the DS18B20
#define DS18B20_PORT GPIOB
#define DS18B20_PIN GPIO1

// Delay function
void ds18b20_delay_us(uint32_t us) {
for (uint32_t i = 0; i < (us * 3); i++) {
__asm__("nop");
}
}

void ds18b20_delay_us_nop() {
	__asm__("nop");

}

// OneWire low-level functions
static void ds18b20_pin_mode_output(void) {
	gpio_mode_setup(DS18B20_PORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, DS18B20_PIN);
}

static void ds18b20_pin_mode_input(void) {
	gpio_mode_setup(DS18B20_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, DS18B20_PIN);
}

static void ds18b20_write_bit(uint8_t bit) {
	ds18b20_pin_mode_output();
	gpio_clear(DS18B20_PORT, DS18B20_PIN);

	if (bit) {
		delay_us(1); // Short low pulse for '1'
		gpio_set(DS18B20_PORT, DS18B20_PIN);
		ds18b20_pin_mode_input();
	}

	delay_us(60);
	ds18b20_pin_mode_input();
	delay_us(10);
}

static uint8_t ds18b20_read_bit(void) {
	uint8_t bit;
	ds18b20_pin_mode_output();
	gpio_clear(DS18B20_PORT, DS18B20_PIN);
//	ds18b20_delay_us(1);
//	gpio_set(DS18B20_PORT, DS18B20_PIN);

	ds18b20_pin_mode_input();
	ds18b20_delay_us(10);
	bit = gpio_get(DS18B20_PORT, DS18B20_PIN);
	ds18b20_delay_us(50);
	return bit;
}

uint8_t ds18b20_reset(void) {
	uint8_t presence;
	ds18b20_pin_mode_output();
	gpio_clear(DS18B20_PORT, DS18B20_PIN);

        ds18b20_delay_us(960);

	ds18b20_pin_mode_input();
        ds18b20_delay_us(120);

	presence = gpio_get(DS18B20_PORT, DS18B20_PIN);

        ds18b20_delay_us(840);

	return presence == 0; // If presence is detected, return 1
}

void ds18b20_write_byte(uint8_t byte) {
	for (uint8_t i = 0; i < 8; i++) {
		ds18b20_write_bit(byte & 0x01);
		byte >>= 1;
	}
	ds18b20_pin_mode_input();
}

/*
uint8_t ds18b20_read_byte(void) {
	uint8_t byte = 0;
	for (uint8_t i = 0; i < 8; i++) {
		byte |= (ds18b20_read_bit() << i);
	}
	return byte;
}
*/
/*
uint8_t ds18b20_read_byte(void) {
	uint8_t i=8, n=0;
	while(i--){
		n>>=1; 
		n |= (ds18b20_read_bit()<<7);
	}
	return n;
}
*/

uint8_t ds18b20_read_byte(void)
{
     uint8_t byte = 0;   	//Value to be returned
     for (uint8_t i = 0; i< 8; i++)//Loop to read the whole byte
     {
    	byte >>= 1;     	//Shift the byte at one bit to the right
    	if (ds18b20_read_bit())  //If 1 has been read
        	byte |= 0x80; 	 //Then add it to the byte
     }
     return (byte);
}


// DS18B20 high-level functions
void ds18b20_start_conversion(void) {
	ds18b20_reset();
	delay_ms(1);
	ds18b20_write_byte(0xCC); // Skip ROM
	delay_ms(1);
	ds18b20_write_byte(0x44); // Start conversion
	delay_ms(1);
}

int16_t ds18b20_read_temperature(void) {
	uint8_t temp_lsb, temp_msb;
	uint8_t temperature[2];
	int8_t digit;
	uint16_t decimal;

	int16_t temp;
	ds18b20_reset();
	ds18b20_write_byte(0xCC); // Skip ROM
	ds18b20_write_byte(0xBE); // Read scratchpad
	temp = ds18b20_read_byte();
	temp |= (uint16_t)(ds18b20_read_byte() << 8);

//	temperature[0] = ds18b20_read_byte();
//	temperature[1] = ds18b20_read_byte();

	ds18b20_reset();
//	temp = (temp_msb << 8) | temp_lsb;

//	digit=temperature[0]>>4; 
//	digit|=(temperature[1]&0x7)<<4; 
	//Store decimal digits 
//	decimal=temperature[0]&0xf; 
//	decimal*=625;

//	temp = (digit * 1000) + decimal;

	//return temp * 0.0625; // Convert to Celsius
//	return temp; // Convert to Celsius
//	return digit;

	if (temp & 0x8000) {  // Check if the sign bit (MSB) is set
		temp = -(int16_t)((~temp + 1) & 0xFFFF);  // Two's complement unary conversion
	}

	return (temp * 625) / 10;
}