working, tested original DS1820

CMakeLists.txt

@@ -19,6 +19,8 @@ set(SOURCE_FILES
         lib/usart.h
         lcd.c
         lcd.h
+        onewire.c
+        onewire.h
         )
 
 include_directories(lib

Makefile

@@ -31,6 +31,7 @@ OBJS += lib/iopins.o
 OBJS += lib/spi.o
 OBJS += lib/adc.o
 OBJS += lcd.o
+OBJS += onewire.o
 
 # Dirs with header files
 INCL_DIRS = . lib/

main.c

@@ -6,19 +6,24 @@
 #include <stdint.h>          // C header for int types like uint8_t
 #include <stdbool.h>         // C header for the bool type
 #include <stdlib.h>
+#include <stdio.h>
 
 // Include stuff from the library
 #include "lib/iopins.h"
 #include "lib/usart.h"
 #include "lcd.h"
+#include "onewire.h"
 
 
 // Pins
 #define LED 13
 
+#define OW_PIN D9
+
 void _lcd_wait_bf();
 void _lcd_write_byte(uint8_t bb);
 
+#if 0
 // UART receive handler
 ISR(USART_RX_vect)
 {
@@ -26,31 +31,81 @@ ISR(USART_RX_vect)
 	uint8_t b = usart_rx();
 	usart_tx(b); // send back
 }
-
+#endif
 
 void main()
 {
+#if 0
 	usart_init(BAUD_115200);
 	usart_isr_rx_enable(true); // enable RX interrupt handler
+#endif
 
 	// configure pins
 	as_output(LED);
 
 	lcd_init();
 
+    lcd_clear();
+    lcd_puts("");
+
 	// globally enable interrupts (for the USART_RX handler)
 	sei();
-	uint8_t cnt = 0;
+
+	uint8_t addr[8];
+	char charbuf[21];
+
+	int dots = 0;
 	while (1) {
+        bool signal = ow_reset(OW_PIN);
+        if (!signal) {
             lcd_clear();
+            lcd_puts("No 1-Wire detected...");
+            dots = 0;
+        } else {
+            ow_write(OW_PIN, 0x33);
+            ow_read_arr(OW_PIN, addr, 8);
 
-		lcd_xy(cnt, 0);
-		lcd_putc('A'+cnt);
+            lcd_clear();
 
-		cnt = (cnt+1)%20;
+            char *p = charbuf;
+            for(uint8_t i = 0; i < 4; i++) {
+                p += sprintf(p, "%02X", addr[i]);
+                if (i < 3) *p++ = ':';
+            }
+            lcd_puts(charbuf);
+            lcd_xy(0, 1);
 
-		pin_toggle(13); // blink the LED
+            p = charbuf;
+            for(uint8_t i = 0; i < 4; i++) {
+                p += sprintf(p, "%02X", addr[4+i]);
+                if (i < 3) *p++ = ':';
+            }
+            lcd_puts(charbuf);
+
+            ds1820_single_measure(OW_PIN);
+            uint16_t cels = ds1820_read_temp_c(OW_PIN);
+
+            if (cels == 850) {
+                lcd_xy(12, 0);
+                for(uint8_t i = 0; i <= dots; i++) {
+                    lcd_putc('.');
+                }
+                dots = (dots+1)%3;
+            } else {
+                p = charbuf;
+                p += sprintf(p, "%d", cels/10);
+                *p++ = '.';
+                p += sprintf(p, "%d", cels%10);
+                *p++ = 0xDF;
+                *p++ = 'C';
+                *p++ = 0;
 
+                lcd_xy(12, 0);
+                lcd_puts(charbuf);
+            }
+        }
+
+		pin_toggle(13); // blink the LED
         _delay_ms(100);
 	}
 }

onewire.c

@@ -0,0 +1,248 @@
+#include <avr/io.h>
+#include <util/delay.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "iopins.h"
+#include "onewire.h"
+
+
+/** Perform bus reset. Returns true if any device is connected */
+bool ow_reset(const uint8_t pin)
+{
+	as_output_n(pin);
+	pin_down_n(pin);
+	_delay_us(480);
+
+	as_input_pu_n(pin);
+	_delay_us(70);
+
+	const bool a = ! pin_read_n(pin);
+
+	_delay_us(410);
+
+	return a;
+}
+
+
+/** Send a single bit */
+void _ow_tx_bit(const uint8_t pin, const bool bit)
+{
+	as_output_n(pin);
+	pin_down_n(pin);
+
+	if (bit)
+	{
+		_delay_us(6);
+		as_input_pu_n(pin);
+		_delay_us(64);
+	}
+	else
+	{
+		_delay_us(60);
+		as_input_pu_n(pin);
+		_delay_us(10);
+	}
+}
+
+
+/** Send a single byte */
+void ow_write(const uint8_t pin, const uint8_t byte)
+{
+	for (uint8_t i = 0; i < 8; i++)
+	{
+		_ow_tx_bit(pin, (byte >> i) & 0x01);
+	}
+}
+
+
+/** Read a single bit */
+bool _ow_rx_bit(const uint8_t pin)
+{
+	as_output_n(pin);
+	pin_down_n(pin);
+	_delay_us(6);
+
+	as_input_pu_n(pin);
+	_delay_us(9);
+
+	const bool a = pin_read_n(pin);
+
+	_delay_us(55);
+
+	return a;
+}
+
+
+/** Read a single byte */
+uint8_t ow_read(const uint8_t pin)
+{
+	uint8_t byte = 0;
+
+	for (uint8_t i = 0; i < 8; i++)
+	{
+		byte = (byte >> 1) | (_ow_rx_bit(pin) << 7);
+	}
+
+	return byte;
+}
+
+
+/** Wait until the device is ready. Returns false on timeout */
+bool ow_wait_ready(const uint8_t pin)
+{
+	uint16_t timeout = 700;
+	as_input_pu_n(pin);
+
+	while (--timeout > 0)
+	{
+		if (pin_is_high_n(pin)) return true;
+		_delay_ms(1);
+	}
+
+	return false;
+}
+
+
+/** Read bytes into an array */
+void ow_read_arr(const uint8_t pin, uint8_t* array, const uint8_t count)
+{
+	for (uint8_t i = 0; i < count; i++)
+	{
+		array[i] = ow_read(pin);
+	}
+}
+
+
+
+// ---------- CRC utils ----------
+
+/*
+ Dallas 1-wire CRC routines for Arduino with examples of usage.
+ The 16-bit routine is new.
+ The 8-bit routine is from http://github.com/paeaetech/paeae/tree/master/Libraries/ds2482/
+
+ Copyright (C) 2010 Kairama Inc
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// Dallas 1-wire 16-bit CRC calculation. Developed from Maxim Application Note 27.
+
+/** Compute a CRC16 checksum */
+uint16_t crc16(uint8_t *data, uint8_t len)
+{
+	uint16_t crc = 0;
+
+	for (uint8_t i = 0; i < len; i++)
+	{
+		uint8_t inbyte = data[i];
+		for (uint8_t j = 0; j < 8; j++)
+		{
+			uint8_t mix = (crc ^ inbyte) & 0x01;
+			crc = crc >> 1;
+			if (mix)
+				crc = crc ^ 0xA001;
+
+			inbyte = inbyte >> 1;
+		}
+	}
+	return crc;
+}
+
+
+// The 1-Wire CRC scheme is described in Maxim Application Note 27:
+// "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
+
+/** Compute a CRC8 checksum */
+uint8_t crc8(uint8_t *addr, uint8_t len)
+{
+	uint8_t crc = 0;
+
+	for (uint8_t i = 0; i < len; i++)
+	{
+		uint8_t inbyte = addr[i];
+		for (uint8_t j = 0; j < 8; j++)
+		{
+			uint8_t mix = (crc ^ inbyte) & 0x01;
+			crc >>= 1;
+			if (mix)
+				crc ^= 0x8C;
+
+			inbyte >>= 1;
+		}
+	}
+
+	return crc;
+}
+
+
+// --- utils for DS1820 ---
+
+
+/** Read temperature in 0.0625°C, or TEMP_ERROR on error */
+int16_t ds1820_read_temp(uint8_t pin)
+{
+	ow_write(pin, READ_SCRATCHPAD);
+	uint8_t bytes[9];
+	ow_read_arr(pin, bytes, 9);
+
+	uint8_t crc = crc8(bytes, 8);
+	if (crc != bytes[8])
+	{
+		return TEMP_ERROR;
+	}
+	else
+	{
+		int16_t a = ((bytes[1] << 8) | bytes[0]) >> 1;
+		a = a << 4;
+		a += (16 - bytes[6]) & 0x0F;
+		a -= 0x04;
+
+		return a;
+	}
+}
+
+/** Read temperature in 0.1°C, or TEMP_ERROR on error */
+int16_t ds1820_read_temp_c(uint8_t pin)
+{
+	int32_t temp = ds1820_read_temp(pin);
+
+	if (temp == TEMP_ERROR)
+		return TEMP_ERROR;
+
+	temp *= 625;
+	uint16_t rem = temp % 1000;
+	temp /= 1000;
+	if (rem >= 500) temp++;
+
+	return (int16_t) temp;
+}
+
+
+bool ds1820_single_measure(uint8_t pin)
+{
+	ow_reset(pin);
+	ow_write(pin, SKIP_ROM);
+	ow_write(pin, CONVERT_T);
+
+	if (!ow_wait_ready(pin))
+	{
+		return false;
+	}
+
+	ow_reset(pin);
+	ow_write(pin, SKIP_ROM);
+
+	return true;
+}

onewire.h

@@ -0,0 +1,58 @@
+#pragma once
+
+//
+// Utils for Dallas OneWire bus (DS1820 etc)
+//
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#define SKIP_ROM  0xCC
+#define CONVERT_T 0x44
+#define READ_SCRATCHPAD 0xBE
+
+/** Perform bus reset. Returns true if any device is connected */
+bool ow_reset(uint8_t pin);
+
+/** Send a single byte */
+void ow_write(const uint8_t pin, const uint8_t byte);
+
+/** Read a single byte */
+uint8_t ow_read(uint8_t pin);
+
+/** Wait until the device is ready. Returns false on timeout */
+bool ow_wait_ready(uint8_t pin);
+
+/** Read bytes into an array */
+void ow_read_arr(uint8_t pin, uint8_t* array, uint8_t count);
+
+/** Compute a CRC16 checksum */
+uint16_t crc16(uint8_t *data, uint8_t len);
+
+/** Compute a CRC8 checksum */
+uint8_t crc8(uint8_t *addr, uint8_t len);
+
+// --- utils for DS1820 ---
+
+#define TEMP_ERROR (-32768)
+
+/**
+ * Read temperature in 0.0625°C, or TEMP_ERROR on error
+ * Use this where you'd normally use READ_SCRATCHPAD
+ */
+int16_t ds1820_read_temp(uint8_t pin);
+
+
+/**
+ * Read temperature in 0.1°C, or TEMP_ERROR on error
+ * Use this where you'd normally use READ_SCRATCHPAD
+ */
+int16_t ds1820_read_temp_c(uint8_t pin);
+
+/**
+ * Perform a temperature measurement with single DS1820 device on the line
+ * Can be followed by a call to read temperature (READ_SCRATCHPAD).
+ *
+ * Returns false on failure (device not connected)
+ */
+bool ds1820_single_measure(uint8_t pin);