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changeset 0:3879f487b661

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Initial commit of routines I copy and paste. Need work to make them more portable (esp cons)
author darius@Inchoate
date Wed, 11 Mar 2009 16:42:27 +1030
parents
children f5022e20d550
files 1wire.c 1wire.h Makefile.avr cons.c cons.h ds1307.c ds1307.h
diffstat 7 files changed, 1607 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/1wire.c	Wed Mar 11 16:42:27 2009 +1030
@@ -0,0 +1,648 @@
+/*
+ * 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 <avr/io.h>
+#include <avr/pgmspace.h>
+#include <util/delay.h>
+#include "1wire.h"
+#include "1wire-config.h"
+#include "cons.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) {
+    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 0
+    OWSETREAD();
+    if(OWREADBUS() == 0)
+	return 2;
+#endif
+
+    OWSETBUSLOW();
+    OWDELAY_H;
+    OWSETBUSHIGH();
+    OWDELAY_I;
+
+    OWSETREAD();
+    return(OWREADBUS());
+}
+
+/*-----------------------------------------------------------------------------
+ * 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) {
+    OWDELAY_I;
+    
+    OWSETBUSLOW();
+    OWDELAY_A;
+    OWSETBUSHIGH();
+    OWDELAY_E;
+    OWSETREAD();
+    return(OWREADBUS());
+}
+
+/*-----------------------------------------------------------------------------
+ * 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:
+		    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)
+ */
+uint8_t
+OWProgROM(uint8_t *ROM, uint8_t start, uint8_t len, uint8_t *data, uint8_t exact, uint8_t status) {
+#if defined(OWSETVPPON) && defined(OWSETVPPOFF)
+    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
+    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 Mar 11 16:42:27 2009 +1030
@@ -0,0 +1,91 @@
+/*
+ * 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.
+ */
+
+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))
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Makefile.avr	Wed Mar 11 16:42:27 2009 +1030
@@ -0,0 +1,57 @@
+#
+# $Id$
+#
+
+.SUFFIXES: .hex .out .c .o .elf .dmp .s
+
+# Otherwise we get -march=foo
+NO_CPU_CFLAGS=
+_CPUCFLAGS=
+
+# Programs
+AS=avr-as
+CC=avr-gcc
+OBJCOPY=avr-objcopy
+OBJDUMP=avr-objdump
+
+# Tell as to generate listings
+CPPFLAGS+=-Wa,-adhlmsn=${<:S/.c/.lst/}
+
+MCU?=at90s8515
+CFLAGS+=-mmcu=${MCU}
+
+LDFLAGS+=-Wl,-Map=${PROG}.map,--cref
+LDFLAGS+=${LDADD}
+
+RM=rm -f
+
+PROGRAMMER=avrdude
+PROGOPTS?=-p ${PART} -c alf -E vcc,noreset -q
+
+.if !defined(SRCS)
+SRCS=	${PROG}.c
+.endif
+
+OBJS+=  ${SRCS:N*.h:R:S/$/.o/g}
+
+all: ${PROG}.hex ${PROG}.dmp
+
+.c.o:
+	${CC} ${CFLAGS} ${CPPFLAGS} -c ${.IMPSRC} -o ${.PREFIX}.o
+
+${PROG}.elf: ${OBJS}
+	${CC} ${CFLAGS} ${LDFLAGS} -g ${OBJS} -o ${PROG}.elf ${LDADD}
+
+.elf.hex:
+	${OBJCOPY} -j .text -j .data -j .bss -j .noinit -O ihex $> $@
+
+.elf.dmp:
+	${OBJDUMP} -S ${.IMPSRC} > ${.PREFIX}.dmp
+
+clean:
+	${RM} ${PROG}.hex ${PROG}.out ${PROG}.elf ${PROG}.map ${OBJS} ${OBJS:S/.o/.lst/} ${PROG}.dmp
+
+prog: all
+	${PROGRAMMER} -U flash:w:${PROG}.hex ${PROGOPTS}
+
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cons.c	Wed Mar 11 16:42:27 2009 +1030
@@ -0,0 +1,179 @@
+/*
+ * Console code for AVR board
+ *
+ * Copyright (c) 2008
+ *      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.
+ */
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <avr/interrupt.h>
+#include <avr/pgmspace.h>
+#include "cons.h"
+
+#define UART_BAUD_SELECT(baudRate,xtalCpu) ((xtalCpu)/((baudRate)*16l)-1)
+
+/* Receive buffer storage */
+consbuf_t cmd;
+
+/*
+ * Stub to use with fdevopen
+ *
+ * We ignore f and always succeed
+ */
+static int _putc(char c, FILE *f) {
+    cons_putc(c);
+    return(0);
+}
+
+/*
+ * Stub to use with fdevopen
+ *
+ * We ignore f and always succeed
+ */
+static int _getc(FILE *f) {
+    return(cons_getc());
+}
+
+void
+cons_init(void) {
+    UBRR0 = UART_BAUD_SELECT(38400, F_CPU);
+    
+    /* Enable receiver and transmitter. Turn on rx interrupts */
+    UCSR0A = 0;
+    UCSR0B = _BV(RXEN0) | _BV(TXEN0) | _BV(RXCIE0);
+    UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);
+
+    fdevopen(_putc, NULL); /* Open stdout */
+    fdevopen(NULL, _getc); /* Open stdin */
+}
+
+int
+cons_putc(char c) {
+    loop_until_bit_is_set(UCSR0A, UDRE0);
+    UDR0 = c;
+
+    return(0);
+}
+
+void
+cons_putsP(const char *addr) {
+    char c;
+
+    while ((c = pgm_read_byte_near(addr++)))
+	cons_putc(c);
+}
+
+void
+cons_puts(const char *addr) {
+    while (*addr)
+	cons_putc(*addr++);
+}
+
+void
+cons_puts_dec(uint8_t a, uint8_t l) {
+    char	s[4];
+    
+    if (l && a < 10)
+	cons_putsP(PSTR("0"));
+    cons_puts(utoa(a, s, 10));
+}
+
+void
+cons_puts_hex(uint8_t a) {
+    char	s[3];
+    
+    if (a < 0x10)
+	cons_putc('0');
+    
+    cons_puts(utoa(a, s, 16));
+}
+
+char
+cons_getc(void) {
+    while (!(UCSR0A & _BV(RXC0)))
+	;
+    
+    return (UDR0);
+}
+
+/* Rx complete */
+ISR(USART0_RX_vect) {
+    volatile char pit;
+    char c;
+
+    while (UCSR0A & _BV(RXC0)) {
+	/* 255 means we're waiting for main to process the command,
+	   just throw stuff away
+	*/
+	if (cmd.state == 255) {
+	    pit = UDR0;
+	    continue;
+	}
+	c = UDR0;
+	
+	/* End of line? */
+	if (c == '\n' || c == '\r') {
+	    cmd.buf[cmd.state] = '\0';
+	    printf_P(PSTR("\r\n"));
+	    cmd.len = cmd.state;
+	    cmd.state = 255;
+	    continue;
+	}
+	
+	/* Backspace/delete */
+	if (c == 0x08 || c == 0x7f) {
+	    if (cmd.state > 0) {
+		cmd.state--;
+		printf_P(PSTR("\010\040\010"));
+	    }
+	    continue;
+	}
+	
+	/* Anything unprintable just ignore it */
+	if (!isprint(c))
+	    continue;
+
+	cmd.buf[cmd.state] = tolower(c);
+
+	/* Echo back to the user */
+	cons_putc(cmd.buf[cmd.state]);
+	
+	cmd.state++;
+	/* Over flow? */
+	if (cmd.state == ((sizeof(cmd.buf) / sizeof(cmd.buf[0])) - 1)) {
+	    printf_P(PSTR("\r\nLine too long"));
+	    cmd.state = 0;
+	    continue;
+	}
+    }
+}
+
+/* Tx complete */
+ISR(USART0_TX_vect) {
+	
+}
+    
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cons.h	Wed Mar 11 16:42:27 2009 +1030
@@ -0,0 +1,44 @@
+/*
+ * Console code headers
+ *
+ * Copyright (c) 2008
+ *      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.
+ */
+
+typedef volatile struct {
+    char	buf[40];
+    uint8_t	state;
+    uint8_t	len;
+} consbuf_t;
+
+extern consbuf_t cmd;
+
+void		cons_init(void);
+void		cons_putsP(const char *addr);
+void		cons_puts(const char *addr);
+int		cons_putc(char c);
+void		cons_puts_dec(uint8_t a, uint8_t l);
+void		cons_puts_hex(uint8_t a);
+char		cons_getc(void);
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ds1307.c	Wed Mar 11 16:42:27 2009 +1030
@@ -0,0 +1,495 @@
+/*
+ * Interface to a DS1307
+ *
+ * Copyright (c) 2008
+ *      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.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <avr/io.h>
+#include <avr/pgmspace.h>
+#include <util/twi.h>
+#include <util/delay.h>
+
+#include "ds1307.h"
+
+// #define TWDEBUG
+
+/* 
+ * ds1307_init
+ *
+ * Setup TWI interface
+ *
+ */
+int
+ds1307_init(void) {
+    PRR &= _BV(PRTWI);		/* Power TWI on - note that the
+				 * datasheet says this is already 0 at
+				 * power on.. */
+    TWSR = 0; 			/* TWI Prescaler = 1 */
+#if F_CPU < 3600000UL
+    TWBR = 10;			/* Smallest valid TWBR */
+#else
+    TWBR = (F_CPU / 100000UL - 16) / 2;
+#endif
+
+    TWCR = _BV(TWEN);
+
+    return(0);
+}
+
+/*
+ * iic_read
+ *
+ * Read len bytes of data from address adr in slave sla into
+ * data. Presume that the slave auto-increments the address on
+ * successive reads.
+ *
+ * Returns the number of bytes read, or the following on failure.
+ * IIC_STFAIL	Could generate START condition (broken bus or busy).
+ * IIC_FAILARB	Failed bus arbitration.
+ * IIC_SLNAK	Slave NAK'd.
+ * IIC_NOREPLY	No reply (no such slave?)
+ * IIC_UNKNOWN	Unexpected return from TWI reg.
+ *
+ * Heaviy cribbed from twitest.c by Joerg Wunsch
+ */
+int8_t
+iic_read(uint8_t *data, uint8_t len, uint8_t adr, uint8_t sla) {
+    uint8_t	twst, twcr, cnt;
+
+    /* Generate START */
+    TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
+
+    /* Spin waiting for START to be generated */
+    while ((TWCR & _BV(TWINT)) == 0)
+	;
+    switch (twst = TW_STATUS) {
+	case TW_REP_START:	/* OK but shouldn't happen */
+	case TW_START:
+	    break;
+	    
+	case TW_MT_ARB_LOST:
+	    return IIC_FAILARB;
+	    break;
+
+	default:
+	    /* Not in start condition, bail */
+	    return IIC_UNKNOWN;
+    }
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent START\r\n"));
+#endif
+    /* Send SLA+W */
+    TWDR = sla | TW_WRITE;
+    TWCR = _BV(TWINT) | _BV(TWEN);
+
+    /* Spin waiting for a response to be generated */
+    while ((TWCR & _BV(TWINT)) == 0)
+	;
+
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent SLA+W\r\n"));
+#endif
+    switch (twst = TW_STATUS) {
+	case TW_MT_SLA_ACK:
+	    break;
+	    
+	case TW_MT_SLA_NACK:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_SLNAK;
+
+	case TW_MT_ARB_LOST:
+	    return IIC_FAILARB;
+	    break;
+
+	default:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_UNKNOWN;
+    }
+    /* Send address */
+    TWDR = adr;
+    TWCR = _BV(TWINT) | _BV(TWEN);
+
+    /* Spin waiting for a response to be generated */
+    while ((TWCR & _BV(TWINT)) == 0)
+	;
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent address\r\n"));
+#endif
+    switch ((twst = TW_STATUS)) {
+	case TW_MT_DATA_ACK:
+	    break;
+
+	case TW_MT_DATA_NACK:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_SLNAK;
+	    
+	case TW_MT_ARB_LOST:
+	    return IIC_FAILARB;
+
+	default:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_UNKNOWN;
+    }
+    
+    /* Master receive cycle */
+    TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
+    while ((TWCR & _BV(TWINT)) == 0) /* wait for transmission */
+	;
+    
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent START\r\n"));
+#endif    
+    switch ((twst = TW_STATUS)) {
+	case TW_REP_START: /* OK but shouldn't happen */
+	case TW_START:
+	    break;
+	    
+	case TW_MT_ARB_LOST:
+	    return IIC_FAILARB;
+	    
+	default:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_UNKNOWN;
+    }
+
+    /* send SLA+R */
+    TWDR = sla | TW_READ;
+    TWCR = _BV(TWINT) | _BV(TWEN); /* clear interrupt to start transmission */
+
+    /* Spin waiting for a response to be generated */
+    while ((TWCR & _BV(TWINT)) == 0)
+	;
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent SLA+R\r\n"));
+#endif
+    switch ((twst = TW_STATUS)) {
+	case TW_MR_SLA_ACK:
+	    break;
+
+	case TW_MR_SLA_NACK:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_SLNAK;
+	    
+	case TW_MR_ARB_LOST:
+	    return IIC_FAILARB;
+	    
+	default:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_UNKNOWN;
+    }
+
+    cnt = 0;
+    for (twcr = _BV(TWINT) | _BV(TWEN) | _BV(TWEA);
+	 len > 0; len--) {
+	/* Send NAK on last byte */
+	if (len == 1)
+	    twcr = _BV(TWINT) | _BV(TWEN); 
+	TWCR = twcr;		/* clear int to start transmission */
+	/* Spin waiting for a response to be generated */
+	while ((TWCR & _BV(TWINT)) == 0)
+	    ;
+#ifdef TWDEBUG
+	printf_P(PSTR("Data request done\r\n"));
+#endif
+	switch ((twst = TW_STATUS)) {
+	    case TW_MR_DATA_NACK:
+		/* Send STOP */
+		TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+		//printf_P(PSTR("NACK on byte %d\r\n"), cnt);
+		return cnt;
+		
+	    case TW_MR_DATA_ACK:
+		*data++ = TWDR;
+		//printf_P(PSTR("ACK on byte %d for 0x%02x\r\n"), cnt, *(data - 1));
+		cnt++;
+		break;
+
+	    default:
+		return IIC_UNKNOWN;
+	}
+    }
+
+    /* Send STOP */
+    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+    return cnt;
+}
+
+/*
+ * iic_write
+ *
+ * Write len bytes of data from address adr in slave sla into
+ * data. Presume that the slave auto-increments the address on
+ * successive writes.
+ *
+ * Returns the number of bytes read, or the following on failure.
+ * IIC_STFAIL	Could generate START condition (broken bus or busy).
+ * IIC_FAILARB	Failed bus arbitration.
+ * IIC_SLNAK	Slave NAK'd.
+ * IIC_NOREPLY	No reply (no such slave?)
+ * IIC_UNKNOWN	Unexpected return from TWI reg.
+ *
+ * Heaviy cribbed from twitest.c by Joerg Wunsch
+ */
+int8_t
+iic_write(uint8_t *data, uint8_t len, uint8_t adr, uint8_t sla) {
+    uint8_t	twst, cnt;
+
+    /* Generate START */
+    TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
+
+    /* Spin waiting for START to be generated */
+    while ((TWCR & _BV(TWINT)) == 0)
+	;
+    switch (twst = TW_STATUS) {
+	case TW_REP_START:	/* OK but shouldn't happen */
+	case TW_START:
+	    break;
+	    
+	case TW_MT_ARB_LOST:
+	    return IIC_FAILARB;
+	    break;
+
+	default:
+	    /* Not in start condition, bail */
+	    return IIC_UNKNOWN;
+    }
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent START\r\n"));
+#endif
+
+    /* Send SLA+W */
+    TWDR = sla | TW_WRITE;
+    TWCR = _BV(TWINT) | _BV(TWEN);
+
+    /* Spin waiting for a response to be generated */
+    while ((TWCR & _BV(TWINT)) == 0)
+	;
+
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent SLA+W\r\n"));
+#endif
+    switch (twst = TW_STATUS) {
+	case TW_MT_SLA_ACK:
+	    break;
+	    
+	case TW_MT_SLA_NACK:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_SLNAK;
+
+	case TW_MT_ARB_LOST:
+	    return IIC_FAILARB;
+	    break;
+
+	default:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_UNKNOWN;
+    }
+    /* Send address */
+    TWDR = adr;
+    TWCR = _BV(TWINT) | _BV(TWEN);
+
+    /* Spin waiting for a response to be generated */
+    while ((TWCR & _BV(TWINT)) == 0)
+	;
+#ifdef TWDEBUG
+    printf_P(PSTR("Sent address\r\n"));
+#endif
+    switch ((twst = TW_STATUS)) {
+	case TW_MT_DATA_ACK:
+	    break;
+
+	case TW_MT_DATA_NACK:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_SLNAK;
+	    
+	case TW_MT_ARB_LOST:
+	    return IIC_FAILARB;
+
+	default:
+	    /* Send STOP */
+	    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+	    return IIC_UNKNOWN;
+    }
+    
+    cnt = 0;
+    for (; len > 0; len--) {
+	TWDR = *data++;
+	TWCR = _BV(TWINT) | _BV(TWEN);
+	
+	/* Spin waiting for a response to be generated */
+	while ((TWCR & _BV(TWINT)) == 0)
+	    ;
+#ifdef TWDEBUG
+    printf_P(PSTR("Data sent\r\n"));
+#endif
+    switch ((twst = TW_STATUS)) {
+	    case TW_MT_DATA_NACK:
+		/* Send STOP */
+		TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+		return cnt;
+		
+	    case TW_MT_DATA_ACK:
+		cnt++;
+		break;
+
+	    default:
+		return IIC_UNKNOWN;
+	}
+    }
+
+    /* Send STOP */
+    TWCR = _BV(TWINT) | _BV(TWSTO) | _BV(TWEN);
+    return cnt;
+}
+
+/* 
+ * ds1307_gettod
+ *
+ * Read time of day from DS1307 into time
+ *
+ * Note that we canonify to 24hr mode.
+ *
+ */
+int8_t
+ds1307_gettod(ds1307raw_t *time) {
+    int8_t len;
+
+    len = iic_read((uint8_t *)time, sizeof(ds1307raw_t) + 1, 0, DS1307_ADR);
+    if (len < 0) {
+	printf_P(PSTR("iic_read failed - %d\r\n"), len);
+	return(0);
+    }
+
+#if 1
+    if (len != sizeof(ds1307raw_t)) {
+	printf_P(PSTR("Only got %d bytes (vs %d)\r\n"), len, sizeof(ds1307raw_t));
+	return(0);
+    }
+#endif
+
+#ifdef TWDEBUG
+    int i;
+    
+    for (i = 0; i < len; i++)
+	printf_P(PSTR("0x%02x: 0x%02x\r\n"), i, *(((uint8_t *)time) + i));
+#endif
+
+    return(1);
+}
+
+/* 
+ * ds1307_settod
+ *
+ * Set the DS1307 with the supplied time, format like so
+ * sc 2008/10/29 23:45:30
+ *
+ */
+int8_t
+ds1307_settod(char *date) {
+    ds1307raw_t rtime;
+    uint16_t year;
+    uint8_t i,  month, day, hour, min, sec;
+
+    if ((i = sscanf_P(date, PSTR("%hu/%hhd/%hhd %hhd:%hhd:%hhd"), &year, &month, &day, &hour, &min, &sec)) != 6) {
+	printf_P(PSTR("Can't parse date\r\n"));
+	return(0);
+    }
+
+    if (year > 1900)
+	year -= 1900;
+    
+    rtime.split.year10 = year / 10;
+    rtime.split.year = year % 10;
+    rtime.split.month10 = month / 10;
+    rtime.split.month = month % 10;
+    rtime.split.day10 = day / 10;
+    rtime.split.day = day % 10;
+    rtime.split.pmam = ((hour / 10) & 0x02) >> 1;
+    rtime.split.hour10 = (hour / 10) & 0x01;
+    rtime.split.hour = hour % 10;
+    rtime.split.min10 = min / 10;
+    rtime.split.min = min % 10;
+    rtime.split.sec10 = sec / 10;
+    rtime.split.sec = sec % 10;
+
+    rtime.split.ch = 0; // Enable clock
+    rtime.split.s1224 = 0; // 24 hour mode
+    rtime.split.dow = 0; // XXX: unused
+    rtime.split.out = 0; // No clock out
+
+#ifdef TWDEBUG
+    for (i = 0; i < sizeof(ds1307raw_t); i++)
+	printf_P(PSTR("0x%02x: 0x%02x\r\n"), i, *(((uint8_t *)&rtime) + i));
+#endif
+    if ((i = iic_write((uint8_t *)&rtime, sizeof(ds1307raw_t), 0, DS1307_ADR)) != sizeof(ds1307raw_t))
+	printf_P(PSTR("Can't write to RTC, sent %d (vs %d)\r\n"), i, sizeof(ds1307raw_t));
+    
+    return(1);
+}
+
+/* 
+ * ds1307_printtime
+ *
+ * Print the time in rtime with trailer
+ *
+ */
+void
+ds1307_printtime(char *leader, char *trailer) {
+    ds1307raw_t rtime;
+    uint8_t hour;
+
+    if (ds1307_gettod(&rtime) != 1)
+	return;
+    
+    // Handle 12/24 hour time
+    hour = rtime.split.hour10 * 10 + rtime.split.hour;
+    if (rtime.split.s1224) {
+	if (rtime.split.pmam)
+	    hour += 12;
+    } else
+	hour += (rtime.split.pmam << 1) * 10;
+	
+    printf_P(PSTR("%S%04d/%02d/%02d %02d:%02d:%02d%S"), leader,
+	     1900 + rtime.split.year10 * 10 + rtime.split.year,
+	     rtime.split.month10 * 10 + rtime.split.month,
+	     rtime.split.day10 * 10 + rtime.split.day,
+	     hour,
+	     rtime.split.min10 * 10 + rtime.split.min,
+	     rtime.split.sec10 * 10 + rtime.split.sec,
+	     trailer);
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ds1307.h	Wed Mar 11 16:42:27 2009 +1030
@@ -0,0 +1,93 @@
+/*
+ * DS1307 headers
+ *
+ * Copyright (c) 2008
+ *      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.
+ */
+
+#define IIC_STFAIL	-1
+#define IIC_FAILARB	-2
+#define IIC_SLNAK	-3
+#define IIC_NOREPLY	-4
+#define IIC_UNKNOWN	-99
+
+#define DS1307_ADR	0xd0	// DS1307's TWI address
+
+typedef struct {
+    uint8_t	year;
+    uint8_t	month;
+    uint8_t	day;
+    uint8_t	hour;
+    uint8_t	min;
+    uint8_t	sec;
+
+    uint8_t	ctrl;
+    uint8_t	ram[56];
+} ds1307_t;
+
+typedef union {
+    uint8_t	raw[8];
+    struct {
+	uint8_t sec	: 4;
+	uint8_t	sec10	: 3;	// Seconds (0-59)
+	uint8_t	ch	: 1;	// Clock enable (1 = off)
+	
+	uint8_t min	: 4;
+	uint8_t min10	: 3;	// Minutes (0-59)
+	uint8_t	pad0	: 1;
+	
+	uint8_t hour	: 4;
+	uint8_t	hour10	: 1;	// Hours
+	uint8_t	pmam	: 1;	// AM/PM => 1 = PM or extra bit for hour10
+	uint8_t	s1224	: 1;	// 1 = 12 hour mode
+	uint8_t pad1	: 1;
+
+	uint8_t dow	: 3;	// Day of the week (1-7)
+	uint8_t	pad2	: 5;	
+	
+	uint8_t	day	: 4;
+	uint8_t day10	: 2;	// Day of the month (1-31)
+	uint8_t pad3	: 2;
+	
+	uint8_t month	: 4;
+	uint8_t month10	: 1;
+	uint8_t	pad4 	: 3;	// Month (1-12)
+	
+	uint8_t year	: 4;
+	uint8_t	year10	: 4;	// Year (0-99)
+	
+	uint8_t	rs	: 2;	// Rate select
+	uint8_t	pad6	: 2;
+	uint8_t sqwe	: 1;	// Square wave enable
+	uint8_t pad5	: 2;
+	uint8_t	out	: 1;	// Output control enable
+    } split;
+} ds1307raw_t;
+	
+int	ds1307_init(void);
+int8_t	iic_read(uint8_t *data, uint8_t len, uint8_t adr, uint8_t sla);
+int8_t	iic_write(uint8_t *data, uint8_t len, uint8_t adr, uint8_t sla);
+int8_t	ds1307_gettod(ds1307raw_t *time);
+int8_t	ds1307_settod(char *date);
+void	ds1307_printtime(char *leader, char *trailer);