From 4e65640929c8c76bb1248ec0a08bdf0411ab6cfc Mon Sep 17 00:00:00 2001
From: smallsolar <solarcene@protonmail.com>
Date: Sat, 5 Apr 2025 22:40:49 +0000
Subject: [PATCH] Add ds18b20.c

---
 ds18b20.c | 167 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 167 insertions(+)
 create mode 100644 ds18b20.c

diff --git a/ds18b20.c b/ds18b20.c
new file mode 100644
index 0000000..c2de5bc
--- /dev/null
+++ b/ds18b20.c
@@ -0,0 +1,167 @@
+#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;
+}
\ No newline at end of file