changeset 13:96c345d304af

Add 1wire code. 1wire.c, 1wire.h and 1wire-config.h are copied avr-lib.
author Daniel O'Connor <darius@dons.net.au>
date Wed, 08 Feb 2012 10:37:22 +1030
parents 093bc0c3b1cc
children 891841f5f785
files 1wire-config.h 1wire.c 1wire.h BSDmakefile hw.c main.c
diffstat 6 files changed, 952 insertions(+), 9 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/1wire-config.h	Wed Feb 08 10:37:22 2012 +1030
@@ -0,0 +1,103 @@
+/*
+ * Example configuration header for 1-wire bus code.
+ *
+ * This is the user servicable stuff - how to do delays and how to
+ * frob the IO pins.
+ *
+ * Copyright (c) 2009
+ *      Daniel O'Connor <darius@dons.net.au>.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * The configuration described here has the 1-wire IO on GPIOE3,
+ * with no pull down, nor VPP
+ */
+
+#include "stm32f10x.h" /* GPIO* */
+#include "hw.h" /* For _usleep16() */
+
+/* Fudge AVR stuff for ARM */
+#define PROGMEM
+#define PSTR(x)			x
+#define pgm_read_byte(x)	*(x)
+
+/* Init bus */
+#define OWBUSINIT()
+
+/* Set the port up to allow reading from the 1 wire bus */
+#define OWSETREAD() 		do {			\
+    GPIO_InitTypeDef GPIO_InitStructure;		\
+    							\
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;		\
+    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;	\
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; \
+    GPIO_Init(GPIOE, &GPIO_InitStructure);		\
+} while (0)
+
+
+/* Read the 1-wire bus, non-inverting logic */
+#define OWREADBUS()		(GPIO_ReadInputDataBit(GPIOE, GPIO_Pin_3) ? 1 : 0)
+
+/* Set the 1-wire bus to 0
+ */
+#define OWSETBUSLOW()		do {			\
+    GPIO_InitTypeDef GPIO_InitStructure;		\
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;		\
+    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;	\
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;	\
+    GPIO_Init(GPIOE, &GPIO_InitStructure);		\
+    GPIO_ResetBits(GPIOE, GPIO_Pin_3);			\
+} while (0)
+
+/* Set the 1-wire bus to 1
+ * Change to input and let the pull up do its job
+ */
+#define OWSETBUSHIGH()		do {			\
+    GPIO_InitTypeDef GPIO_InitStructure;		\
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;		\
+    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;	\
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; \
+    GPIO_Init(GPIOE, &GPIO_InitStructure);		\
+} while (0)
+
+#define OWDELAY_A _usleep16(6)						/* 6 usec */
+#define OWDELAY_B _usleep16(64)						/* 64 usec */
+#define OWDELAY_C _usleep16(60)						/* 60 usec */
+#define OWDELAY_D _usleep16(10)						/* 10 usec */
+#define OWDELAY_E _usleep16(9)						/* 9 usec */
+#define OWDELAY_F _usleep16(55)						/* 55 usec */
+#define OWDELAY_G							/* 0 usec */
+#define OWDELAY_H _usleep16(480)					/* 480 usec */
+#define OWDELAY_I _usleep16(70)						/* 70 usec */
+#define OWDELAY_J _usleep16(410)					/* 410 usec */
+
+#ifdef OW_DEBUG
+#define OWPUTS(x)		puts(x)
+#define OWPUTSP(x)		puts(x)
+#define OWPRINTFP(fmt, ...)	printf(fmt, ## __VA_ARGS__)
+#else
+#define OWPUTS(x)
+#define OWPUTSP(x)
+#define OWPRINTFP(fmt, ...)
+#endif
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/1wire.c	Wed Feb 08 10:37:22 2012 +1030
@@ -0,0 +1,658 @@
+/*
+ * Various 1 wire routines
+ * Search routine is copied from the Dallas owpd library with mods
+ * available from here http://www.ibutton.com/software/1wire/wirekit.html
+ *
+ * $Id$
+ *
+ * Copyright (c) 2004
+ *      Daniel O'Connor <darius@dons.net.au>.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* 
+ * No user servicable parts inside
+ *
+ * Modify 1wire-config.h
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include "1wire-config.h"
+#include "1wire.h"
+
+static uint8_t OW_LastDevice = 0;
+static uint8_t OW_LastDiscrepancy = 0;
+static uint8_t OW_LastFamilyDiscrepancy = 0;
+
+const PROGMEM char *OWProgROM_Status[] = {
+    "OK",
+    "no HW support",
+    "Invalid params",
+    "module missing/broken"
+};
+
+/*-----------------------------------------------------------------------------
+ * Configure the IO port as we need
+ */
+void
+OWInit(void) {
+    OWBUSINIT();
+    OWSETBUSHIGH();
+}
+
+/*-----------------------------------------------------------------------------
+ * Generate a 1-Wire reset, return 0 if presence pulse was found, 1 if it
+ * wasn't, or 2 if the line appears to be being held low.
+ * 
+ * (NOTE: Does not handle alarm presence from DS2404/DS1994)
+ */
+uint8_t
+OWTouchReset(void) {
+    uint8_t	i;
+    
+    OWDELAY_G;
+
+    /* Check the bus isn't being held low (ie it's broken) Do it after
+     * the delay so we guarantee we don't see a slave from a previous
+     * comms attempt
+     */
+#if 1
+    OWSETREAD();
+    if(OWREADBUS() == 0)
+	return 2;
+#endif
+
+    OWSETBUSLOW();
+    OWDELAY_H;
+    OWSETBUSHIGH();
+    OWDELAY_I;
+
+    OWSETREAD();
+    i = OWREADBUS();
+
+    OWDELAY_J;
+    return(i);
+}
+
+/*-----------------------------------------------------------------------------
+ * Send a 1-wire write bit.
+ */
+void
+OWWriteBit(uint8_t bit) {
+    OWDELAY_I;
+    
+    if (bit) {
+	OWSETBUSLOW();
+	OWDELAY_A;
+	OWSETBUSHIGH();
+	OWDELAY_B;
+    } else {
+	OWSETBUSLOW();
+	OWDELAY_C;
+	OWSETBUSHIGH();
+	OWDELAY_D;
+    }
+}
+
+/*-----------------------------------------------------------------------------
+ * Read a bit from the 1-wire bus and return it.
+ */
+uint8_t
+OWReadBit(void) {
+    uint8_t	i;
+    
+    OWDELAY_I;
+    
+    OWSETBUSLOW();
+    OWDELAY_A;
+    OWSETBUSHIGH();
+    OWDELAY_E;
+    OWSETREAD();
+    i = OWREADBUS();
+    OWDELAY_F;
+    return(i);
+}
+
+/*-----------------------------------------------------------------------------
+ * Write a byte to the 1-wire bus
+ */
+void
+OWWriteByte(uint8_t data) {
+    uint8_t i;
+    
+    /* Send LSB first */
+    for (i = 0; i < 8; i++) {
+	OWWriteBit(data & 0x01);
+	data >>= 1;
+    }
+}
+
+/*-----------------------------------------------------------------------------
+ * Read a byte from the 1-wire bus
+ */
+uint8_t
+OWReadByte(void) {
+    int i, result = 0;
+    
+    for (i = 0; i < 8; i++) {
+	result >>= 1;
+	if (OWReadBit())
+	    result |= 0x80;
+    }
+    return(result);
+}
+
+/*-----------------------------------------------------------------------------
+ * Write a 1-wire data byte and return the sampled result.
+ */
+uint8_t
+OWTouchByte(uint8_t data) {
+    uint8_t i, result = 0;
+    
+    for (i = 0; i < 8; i++) {
+	result >>= 1;
+	
+	/* If sending a 1 then read a bit, otherwise write a 0 */
+	if (data & 0x01) {
+	    if (OWReadBit())
+		result |= 0x80;
+	} else
+	    OWWriteBit(0);
+	
+	data >>= 1;
+    }
+
+    return(result);
+}
+
+/*-----------------------------------------------------------------------------
+ * Write a block of bytes to the 1-wire bus and return the sampled result in
+ * the same buffer
+ */
+void
+OWBlock(uint8_t *data, int len) {
+    int i;
+    
+    for (i = 0; i < len; i++)
+	data[i] = OWTouchByte(data[i]);
+}
+
+
+/*-----------------------------------------------------------------------------
+ * Send a 1 wire command to a device, or all if no ROM ID provided
+ */
+void
+OWSendCmd(uint8_t *ROM, uint8_t cmd) {
+    uint8_t	i;
+
+    OWTouchReset();
+    
+    if (ROM == NULL)
+	OWWriteByte(OW_SKIP_ROM_CMD);
+    else {
+	OWWriteByte(OW_MATCH_ROM_CMD);
+	for (i = 0; i < 8; i++)
+	    OWWriteByte(ROM[i]);
+    }
+    OWWriteByte(cmd);
+}
+
+/*-----------------------------------------------------------------------------
+ * Search algorithm from App note 187 (and 162)
+ *
+ * OWFirst/OWNext return..
+ *         1 when something is found,
+ *         0 no more modules
+ *	   -1 if no presence pulse,
+ *         -2 if bad CRC,
+ *         -3 if bad wiring.
+ */
+uint8_t
+OWFirst(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) {
+    /* Reset state */
+    OW_LastDiscrepancy = 0;
+    OW_LastDevice = 0;
+    OW_LastFamilyDiscrepancy = 0;
+    
+    /* Go looking */
+    return (OWNext(ROM, do_reset, alarm_only));
+}
+
+/* Returns 1 when something is found, 0 if nothing left */
+uint8_t
+OWNext(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only) {
+    uint8_t	bit_test, search_direction, bit_number;
+    uint8_t	last_zero, rom_byte_number, rom_byte_mask;
+    uint8_t	lastcrc8, crcaccum;
+    int8_t	next_result;
+
+    /* Init for search */
+    bit_number = 1;
+    last_zero = 0;
+    rom_byte_number = 0;
+    rom_byte_mask = 1;
+    next_result = OW_NOMODULES;
+    lastcrc8 = 0;
+    crcaccum = 0;
+
+    /* if the last call was not the last one */
+    if (!OW_LastDevice) {
+	/* check if reset first is requested */
+	if (do_reset) {
+	    /* reset the 1-wire
+	     * if there are no parts on 1-wire, return 0 */
+	    OWPUTSP(PSTR("Resetting\r\n"));
+	    switch (OWTouchReset()) {
+		case 0:
+		    OWPUTSP(PSTR("Found device(s)\r\n"));
+		    break;
+		    
+		case 1:
+		    /* reset the search */
+		    OW_LastDiscrepancy = 0;
+		    OW_LastFamilyDiscrepancy = 0;
+		    OWPUTSP(PSTR("No devices on bus\r\n"));
+		    return OW_NOPRESENCE;
+		    break;
+		
+		case 2:
+		    /* reset the search */
+		    OW_LastDiscrepancy = 0;
+		    OW_LastFamilyDiscrepancy = 0;
+		    OWPUTSP(PSTR("Bus appears to be being held low\r\n"));
+		    return OW_BADWIRE;
+		break;
+		    
+	    }
+	}
+
+	/* If finding alarming devices issue a different command */
+	if (alarm_only)
+	    OWWriteByte(OW_SEARCH_ALRM_CMD);	/* issue the alarming search command */
+	else
+	    OWWriteByte(OW_SEARCH_ROM_CMD);	/* issue the search command */
+
+	/* pause before beginning the search */
+	OWDELAY_I;
+	OWDELAY_I;
+	OWDELAY_I;
+	
+	/* loop to do the search */
+	do {
+	    /* read a bit and its compliment */
+	    bit_test = OWReadBit() << 1;
+	    bit_test |= OWReadBit();
+
+	    OWPRINTFP(PSTR("bit_test = %d\r\n"), bit_test);
+
+	    /* check for no devices on 1-wire */
+	    if (bit_test == 3) {
+		OWPRINTFP(PSTR("bit_test = %d\r\n"), bit_test);
+		return(OW_BADWIRE);
+	    }
+	    else {
+		/* all devices coupled have 0 or 1 */
+		if (bit_test > 0)
+		    search_direction = !(bit_test & 0x01);  /* bit write value for search */
+		else {
+		    /* if this discrepancy is before the Last Discrepancy
+		     * on a previous OWNext then pick the same as last time */
+		    if (bit_number < OW_LastDiscrepancy)
+			search_direction = ((ROM[rom_byte_number] & rom_byte_mask) > 0);
+		    else
+			/* if equal to last pick 1, if not then pick 0 */
+			search_direction = (bit_number == OW_LastDiscrepancy);
+
+		    /* if 0 was picked then record its position in LastZero */
+		    if (search_direction == 0) {
+			last_zero = bit_number;
+
+			/* check for Last discrepancy in family */
+			if (last_zero < 9)
+			    OW_LastFamilyDiscrepancy = last_zero;
+		    }
+		}
+
+		/* set or clear the bit in the ROM byte rom_byte_number
+		 * with mask rom_byte_mask */
+		if (search_direction == 1)
+		    ROM[rom_byte_number] |= rom_byte_mask;
+		else
+		    ROM[rom_byte_number] &= ~rom_byte_mask;
+
+		/* serial number search direction write bit */
+		OWWriteBit(search_direction);
+
+		/* increment the byte counter bit_number
+		 * and shift the mask rom_byte_mask */
+		bit_number++;
+		rom_byte_mask <<= 1;
+
+		/* if the mask is 0 then go to new ROM byte rom_byte_number
+		 * and reset mask */
+		if (rom_byte_mask == 0) {
+		    OWCRC(ROM[rom_byte_number], &crcaccum);  /* accumulate the CRC */
+		    lastcrc8 = crcaccum;
+		  
+		    rom_byte_number++;
+		    rom_byte_mask = 1;
+		}
+	    }
+	} while (rom_byte_number < 8);  /* loop until through all ROM bytes 0-7 */
+
+	/* if the search was successful then */
+	if (!(bit_number < 65) || lastcrc8) {
+	    if (lastcrc8) {
+		OWPRINTFP(PSTR("Bad CRC (%d)\r\n"), lastcrc8);
+		next_result = OW_BADCRC;
+	    } else {
+		/*  search successful so set LastDiscrepancy,LastDevice,next_result */
+		OW_LastDiscrepancy = last_zero;
+		OW_LastDevice = (OW_LastDiscrepancy == 0);
+		OWPRINTFP(PSTR("Last device = %d\r\n"), OW_LastDevice);
+		next_result = OW_FOUND;
+	    }
+	}
+    }
+
+    /* if no device found then reset counters so next 'next' will be
+     * like a first */
+    if (next_result != OW_FOUND || ROM[0] == 0) {
+	OW_LastDiscrepancy = 0;
+	OW_LastDevice = 0;
+	OW_LastFamilyDiscrepancy = 0;
+    }
+
+    if (next_result == OW_FOUND && ROM[0] == 0x00)
+	next_result = OW_BADWIRE;
+   
+    return next_result;
+
+}
+
+uint8_t PROGMEM dscrc_table[] = { 
+    0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
+    157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
+    35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
+    190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
+    70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
+    219, 133,103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
+    101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
+    248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
+    140,210, 48, 110, 237, 179, 81, 15, 78, 16, 242,  172, 47, 113,147, 205,
+    17, 79, 173, 243, 112, 46, 204, 146, 211,141, 111, 49, 178, 236, 14, 80,
+    175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82,176, 238,
+    50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
+    202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
+    87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
+    233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
+    116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
+};
+
+/*-----------------------------------------------------------------------------
+ * Update *crc based on the value of x
+ */
+void
+OWCRC(uint8_t x, uint8_t *crc) {
+    *crc = pgm_read_byte(&dscrc_table[(*crc) ^ x]);
+}
+
+/*-----------------------------------------------------------------------------
+ * Program a DS2502's memory
+ *
+ * Arguments
+ * ROM - ROM ID (or NULL to send SKIP_ROM)
+ * start  - Start address (bytes)
+ * len    - Length of data to write
+ * data   - Data to write
+ * exact  - If true, only accept exact matches for programming,
+ *          otherwise only ensure the bits we requested were 
+ *          programmed [to 0]
+ * status - If true program status rather than memory
+ *
+ * Returns..
+ *  0 if all is OK
+ *  1 if the programming is not possible
+ *  2 if the parameters were invalid
+ *  3 if the DS2502 didn't respond appropriately (also happens if the
+ *  module doesn't exist)
+ */
+#if defined(OWSETVPPON) && defined(OWSETVPPOFF)
+uint8_t
+OWProgROM(uint8_t *ROM, uint8_t start, uint8_t len, uint8_t *data, uint8_t exact, uint8_t status) {
+    uint8_t	crc, i, tmp;
+    
+    /* Stupid programmer detection */
+    if (status) {
+	if (start + len > 3)
+	    return(2);
+    } else {
+	if (start  + len > 127)
+	    return(2);
+    }
+    
+    if (len < 1)
+	return(2);
+    
+    OWDELAY_I;
+    if (OWTouchReset() != 0) {
+	cons_putsP(PSTR("No presence pulse\r\n"));
+	return(3);
+    }
+    
+    crc = 0;
+    
+    /* Send the command */
+    if (status) {
+	OWSendCmd(ROM, OW_WRITE_STATUS);
+	OWCRC(OW_WRITE_STATUS, &crc);
+    } else {
+	OWSendCmd(ROM, OW_WRITE_MEMORY);
+	OWCRC(OW_WRITE_MEMORY, &crc);
+    }
+    
+    /* And the start address
+     * (2 bytes even though one would do)
+     */
+    OWWriteByte(start);
+    OWCRC(start, &crc);
+
+    OWWriteByte(0x00);
+    OWCRC(0x00, &crc);
+
+    for (i = 0; i < len; i++) {
+	cons_putsP(PSTR("Programming "));
+	cons_puts_hex(data[i]);
+	cons_putsP(PSTR(" to "));
+	cons_puts_hex(start + i);
+	cons_putsP(PSTR("\r\n"));
+
+	OWWriteByte(data[i]);
+	OWCRC(data[i], &crc);
+    
+	tmp = OWReadByte();
+	
+	if (crc != tmp) {
+	    cons_putsP(PSTR("CRC mismatch "));
+	    cons_puts_hex(crc);
+	    cons_putsP(PSTR(" vs "));
+	    cons_puts_hex(tmp);
+	    cons_putsP(PSTR("\r\n"));
+
+	    OWTouchReset();
+	    return(3);
+	}
+	
+	OWSETVPPON();
+	OWDELAY_H;
+	OWSETVPPOFF();
+
+	tmp = OWReadByte();
+
+	/* Check the bits we turned off are off */
+/*
+        for (i = 0; i < 8; i++)
+	    if (!(data[i] & 1 << i) && (tmp & 1 << i))
+	        return(-3);
+*/
+	if ((!data[i] & tmp) != 0) {
+	    cons_putsP(PSTR("Readback mismatch "));
+	    cons_puts_hex(data[i]);
+	    cons_putsP(PSTR(" vs "));
+	    cons_puts_hex(data[i]);
+	    cons_putsP(PSTR("\r\n"));
+	    
+	    OWTouchReset();
+	    return(3);
+	}
+	
+	/* The DS2502 loads it's CRC register with the address of the
+	 * next byte */
+	crc = 0;
+	OWCRC(start + i + 1, &crc);
+    }
+
+    return(0);
+}
+#else
+uint8_t
+OWProgROM(uint8_t *ROM __attribute((unused)), uint8_t start __attribute((unused)), uint8_t len __attribute((unused)), uint8_t *data __attribute((unused)), uint8_t exact __attribute((unused)), uint8_t status __attribute((unused))) {
+    return(1);
+}
+#endif
+
+/* 
+ * OWGetTemp
+ *
+ * Get the temperature from a 1wire bus module
+ *
+ * Returns temperature in hundredths of a degree or OW_TEMP_xxx on
+ * error.
+ */
+int16_t
+OWGetTemp(uint8_t *ROM) {
+    int8_t	i;
+    uint8_t	crc, buf[9];
+    int16_t	temp;
+    int16_t	tfrac;
+    
+    if (ROM[0] != OW_FAMILY_TEMP)
+	return OW_TEMP_WRONG_FAM;
+    
+    OWSendCmd(ROM, OW_CONVERTT_CMD);
+    
+    i = 0;
+
+    /* Wait for the conversion */
+    while (OWReadBit() == 0)
+	i = 1;
+
+    /* Check that we talked to a module and it did something  */
+    if (i == 0) {
+	return OW_TEMP_NO_ROM;
+    }
+    
+    OWSendCmd(ROM, OW_RD_SCR_CMD);
+    crc = 0;
+    for (i = 0; i < 8; i++) {
+	buf[i] = OWReadByte();
+	OWCRC(buf[i], &crc);
+    }
+    buf[i] = OWReadByte();
+    if (crc != buf[8])
+	return OW_TEMP_CRC_ERR;
+    temp = buf[0];
+    if (buf[1] & 0x80)
+	temp -= 256;
+
+    /* Chop off 0.5 degree bit */
+    temp >>= 1;
+
+    /* Calulate the fractional remainder */
+    tfrac = buf[7] - buf[6];
+
+    /* Work in 100'th of degreess to save on floats */
+    tfrac *= (int16_t)100;
+
+    /* Divide by count */
+    tfrac /= buf[7];
+
+    /* Subtract 0.25 deg from temp */
+    tfrac += 75;
+    if (tfrac < 100)
+	temp--;
+    else
+	tfrac -= 100;
+
+    i = temp;
+    temp *= 100;
+    temp += tfrac;
+
+    return(temp);
+}
+
+/*
+ * OWTempStatusStr
+ *
+ * Return a string for each OW_TEMP_xxx error code
+ *
+ * shrt = 1 returns short strings
+ *
+ */
+const char *
+OWTempStatusStr(int16_t val, uint8_t shrt) {
+    if (val > OW_TEMP_BADVAL) {
+        if (shrt)
+            return PSTR("OK");
+        else
+            return PSTR("OK");
+    }
+
+    switch (val) {
+        case OW_TEMP_WRONG_FAM:
+            if (shrt)
+                return PSTR("WrFam");
+            else
+                return PSTR("Wrong family");
+            break;
+        case OW_TEMP_CRC_ERR:
+            if (shrt)
+                return PSTR("CRCErr");
+            else
+                return PSTR("CRC Error");
+            break;
+        case OW_TEMP_NO_ROM:
+            if (shrt)
+                return PSTR("NoROM");
+            else
+                return PSTR("ROM did not reply");
+            break;
+        default:
+            if (shrt)
+                return PSTR("???");
+            else
+                return PSTR("Unknown error code");
+            break;
+    }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/1wire.h	Wed Feb 08 10:37:22 2012 +1030
@@ -0,0 +1,95 @@
+/*
+ * 1 wire header which defines functions and constants
+ *
+ * $Id$
+ *
+ * Copyright (c) 2004
+ *      Daniel O'Connor <darius@dons.net.au>.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef PROGMEM
+#define PROGMEM
+#endif
+
+void		OWInit(void);
+uint8_t		OWTouchReset(void);
+void		OWWriteBit(uint8_t bit);
+uint8_t		OWReadBit(void);
+void		OWWriteByte(uint8_t data);
+uint8_t		OWReadByte(void);
+uint8_t		OWTouchByte(uint8_t data);
+void		OWBlock(uint8_t *data, int len);
+uint8_t		OWFirst(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only);
+uint8_t		OWNext(uint8_t *ROM, uint8_t do_reset, uint8_t alarm_only);
+void		OWCRC(uint8_t x, uint8_t *crc);
+void		OWSendCmd(uint8_t *ROM, uint8_t cmd);
+uint8_t		OWProgROM(uint8_t *ROM, uint8_t start, uint8_t len, uint8_t *data, uint8_t exact, uint8_t status);
+int16_t		OWGetTemp(uint8_t *ROM);
+const PROGMEM char *OWTempStatusStr(int16_t val, uint8_t shrt);
+extern const PROGMEM char *OWProgROM_Status[];
+
+
+/* Return codes for OWFirst()/OWNext() */
+#define OW_BADWIRE		-3
+#define OW_BADCRC		-2
+#define OW_NOPRESENCE		-1
+#define OW_NOMODULES		0
+#define OW_FOUND		1
+
+/* General 1 wire commands */
+#define OW_OVRDRV_SKIP_CMD	0x3c
+#define OW_SEARCH_ALRM_CMD	0xec
+#define OW_SEARCH_ROM_CMD	0xf0
+#define OW_READ_ROM_CMD		0x33
+#define OW_MATCH_ROM_CMD	0x55
+#define OW_SKIP_ROM_CMD		0xcc
+
+/* DS1820 commands */
+#define OW_CONVERTT_CMD		0x44
+#define OW_RD_SCR_CMD		0xbe
+#define OW_WR_SCR_CMD		0x4e
+#define OW_CPY_SCR_CMD		0x48
+#define OW_RECALL_CMD		0xb8
+#define OW_RD_PSU_CMD		0xb4
+
+/* DS2502 commands */
+#define OW_READ_MEMORY		0xf0
+#define OW_READ_STATUS		0xaa
+#define OW_GEN_CRC		0xc3
+#define OW_WRITE_MEMORY		0x0f
+#define OW_WRITE_STATUS		0x55
+
+/* Family codes */
+#define OW_FAMILY_ROM		0x09
+#define OW_FAMILY_TEMP		0x10
+
+/* Return codes for OWGetTemp */
+#define OW_TEMP_BADVAL		-6000
+#define OW_TEMP_WRONG_FAM	-6001
+#define OW_TEMP_CRC_ERR		-6002
+#define OW_TEMP_NO_ROM		-6003
+
+/* Helpers for OWGetTemp's number system */
+#define GETWHOLE(x)	((x) / 100)
+#define GETFRAC(x)	abs((x) - (GETWHOLE(x) * 100))
--- a/BSDmakefile	Mon Feb 06 23:55:53 2012 +1030
+++ b/BSDmakefile	Wed Feb 08 10:37:22 2012 +1030
@@ -1,6 +1,7 @@
 PROG=		main
 
-SRCS=		comm.c \
+SRCS=		1wire.c \
+		comm.c \
 		core_cm3.c \
 		delay.c \
 		flash.c \
--- a/hw.c	Mon Feb 06 23:55:53 2012 +1030
+++ b/hw.c	Wed Feb 08 10:37:22 2012 +1030
@@ -1,21 +1,24 @@
 #include <stdint.h>
 #include <stdio.h>
 #include "stm32f10x.h"
+
+#include "1wire.h"
 #include "lcd.h"
 
 static void	hw_port_cfg(void);
 
 /* Wait for cnt microseconds */
-void _usleep16(uint16_t cnt) {
-    TIM6->ARR = cnt;
+void
+_usleep16(uint16_t cnt) {
+    TIM6->ARR = cnt > 3 ? cnt - 3 : cnt;
     TIM_SetCounter(TIM6, 0);
     TIM_Cmd(TIM6, ENABLE);
     while ((TIM6->CR1 & TIM_CR1_CEN) != 0)
 	;
-    
 }
 
-void hw_init(void) {
+void
+hw_init(void) {
     hw_port_cfg();
     lcd_init();
     lcd_setpwm(1000);
@@ -279,17 +282,33 @@
 
     /* Time Base configuration */
     TIM_TimeBaseStructure.TIM_Period = 0;
-    TIM_TimeBaseStructure.TIM_Prescaler = (SystemCoreClock / 1000000) - 1; /* 1 MHz clock */
+    TIM_TimeBaseStructure.TIM_Prescaler = (SystemCoreClock / 2 / 1000000) - 1; /* 1 MHz clock */
     TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);
 
     TIM_Cmd(TIM6, DISABLE);
 
-    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
+    /* Setup for single pulse mode clear UDIS */
+    TIM_SelectOnePulseMode(TIM6, TIM_OPMode_Single);
+    TIM_UpdateDisableConfig(TIM6, DISABLE);
+
+    /* Setup GPIO for 1-wire */
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
     GPIO_Init(GPIOE, &GPIO_InitStructure);
 
-    TIM_SelectOnePulseMode(TIM6, TIM_OPMode_Single);
-    TIM_UpdateDisableConfig(TIM6, DISABLE);
+    OWInit();
 
+#if 0
+    while (1) {
+	GPIO_SetBits(GPIOE, GPIO_Pin_2);
+	_usleep16(10);
+	GPIO_ResetBits(GPIOE, GPIO_Pin_2);
+	_usleep16(20);
+	GPIO_SetBits(GPIOE, GPIO_Pin_2);
+	_usleep16(30);
+	GPIO_ResetBits(GPIOE, GPIO_Pin_2);
+	_usleep16(100);
+    }
+#endif    
 }
--- a/main.c	Mon Feb 06 23:55:53 2012 +1030
+++ b/main.c	Wed Feb 08 10:37:22 2012 +1030
@@ -9,6 +9,7 @@
 
 #include "stm32f10x.h"
 
+#include "1wire.h"
 #include "comm.h"
 #include "delay.h"
 #include "flash.h"
@@ -243,6 +244,72 @@
 		    GPIO_ResetBits(GPIOE, GPIO_Pin_3);
 		    _usleep16(60000);
 		}
+	    } else if (!strncmp("rs", cmd.buf, 2)) {
+		printf("Reset got %d\r\n", OWTouchReset());
+	    } else if (!strncmp("sr", cmd.buf, 2)) {
+		uint8_t	ROM[8];
+		int8_t	i;
+	
+		memset(ROM, 0, 8);
+
+		i = OWFirst(ROM, 1, 0);
+		do {
+		    switch (i) {
+			case OW_NOMODULES:
+			case OW_FOUND:
+			    break;
+		    
+			case OW_BADWIRE:
+			case OW_NOPRESENCE:
+			case OW_BADCRC:
+			default:
+			    printf("Err %d\r\n", i);
+			    break;
+		    }
+		
+		    if (i != OW_FOUND)
+			break;
+
+		    for (i = 0; i < 8; i++)
+			printf("%02x%s", ROM[i], i == 7 ? "\r\n" : ":");
+
+		    i = OWNext(ROM, 1, 0);
+		} while (1);
+	    } else if (!strncmp("rb", cmd.buf, 2)) {
+		printf("Read bit returned %d\r\n", OWReadBit());
+	    } else if (!strncmp("wb ", cmd.buf, 3)) {
+		x = atoi(cmd.buf + 3);
+		OWWriteBit(x);
+		printf("Wrote %d\r\n", x);
+	    } else if (!strncasecmp(cmd.buf, "te ", 3)) {
+		uint8_t	ROM[8];
+		int16_t	res;
+	
+		if (sscanf(cmd.buf, "te %hhx:%hhx:%hhx:%hhx:%hhx:%hhx:%hhx:%hhx", 
+			   &ROM[0], &ROM[1], &ROM[2], &ROM[3],
+			   &ROM[4], &ROM[5], &ROM[6], &ROM[7]) != 8) {
+		    printf("Unable to parse ROM ID\r\n");
+		    goto out;
+		}
+
+		res = OWGetTemp(ROM);
+		switch (res) {
+		    case OW_TEMP_WRONG_FAM:
+			printf("ROM specified isn't a temperature sensor\r\n");
+			break;
+
+		    case OW_TEMP_CRC_ERR:
+			printf("CRC mismatch\r\n");
+			break;
+
+		    case OW_TEMP_NO_ROM:
+			printf("No ROM found\r\n");
+			break;
+
+		    default:
+			printf("%hd.%02hd\r\n", GETWHOLE(res), GETFRAC(res));
+			break;
+		}
 	    } else if (!strncmp("zz", cmd.buf, 2)) {
 		NVIC_SystemReset();
 	    } else {