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Add onewire support to the wixel. Measure temperatures using a DS1820…

… or DS18B20.
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commit 060d47ba0f07ee39c710f863f9e05c3e52ca282b 1 parent 6fa784a
@RussNelson RussNelson authored
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153 apps/example_onewire/example_onewire.c
@@ -0,0 +1,153 @@
+/** example_onewire: read Dallas Semiconductor OneWire devices.
+ */
+
+#include <cc2511_map.h>
+#include <wixel.h>
+#include <usb.h>
+#include <usb_com.h>
+#include <time.h>
+#include <stdio.h>
+#include <math.h>
+
+#include "onewire.h"
+
+const char *respondstr = NULL;
+
+uint8 XDATA DS1820_addr[8];
+uint8 is_DS18B20;
+uint32 ds1820_time;
+
+void start_DS1820()
+{
+ onewire_reset();
+ onewire_select(DS1820_addr);
+ onewire_write(0x44,0); // start conversion, with parasite power off at the end
+}
+
+void setup_DS1820(void) {
+ onewire_start();
+ if ( !onewire_search(DS1820_addr)) {
+ onewire_reset_search();
+ delayMs(250);
+ onewire_search(DS1820_addr);
+ }
+
+ if ( onewire_crc8( DS1820_addr, 7) != DS1820_addr[7]) {
+ respondstr = "No OneWire devices found";
+ return;
+ }
+
+ if ( DS1820_addr[0] == 0x10) {
+ is_DS18B20 = FALSE;
+ } else if ( DS1820_addr[0] == 0x28) {
+ is_DS18B20 = TRUE;
+ } else {
+ respondstr = "No DS1820 found";
+ return;
+ }
+
+ start_DS1820();
+ ds1820_time = getMs();
+}
+
+
+// return the temperature in C multiplied by 16
+int read_DS1820()
+{
+ uint8 i;
+ uint8 present = 0;
+ uint8 dataread[12];
+ int temp_read;
+
+ // we might do a ds.depower() here, but the reset will take care of it.
+
+ present = onewire_reset();
+ onewire_select(DS1820_addr);
+ onewire_write(0xBE,0); // Read Scratchpad
+ for ( i = 0; i < 9; i++) { // we need 9 bytes
+ dataread[i] = onewire_read();
+ }
+ temp_read = ((dataread[1] << 8) | dataread[0]);
+ if (!is_DS18B20) {
+ // temp_read is currently in half degrees.
+ temp_read *= 8.0;
+ //
+ temp_read += - ( 8 * (dataread[7]- dataread[6]) )/dataread[7];
+ }
+ return temp_read;
+}
+
+
+void updateLeds()
+{
+ usbShowStatusWithGreenLed();
+
+ //LED_YELLOW_TOGGLE();
+ //LED_YELLOW(1);
+
+ LED_RED(0);
+}
+
+uint8 nibbleToAscii(uint8 nibble)
+{
+ nibble &= 0xF;
+ if (nibble <= 0x9){ return '0' + nibble; }
+ else{ return 'A' + (nibble - 0xA); }
+}
+
+void handleOneWire(void)
+{
+ int i;
+ int newtemp = 0;
+ int air_temp_c;
+ unsigned int decimals;
+
+ if (getMs() > ds1820_time + 1000) {
+ air_temp_c = read_DS1820();
+ newtemp++;
+ start_DS1820();
+ ds1820_time = getMs();
+ }
+
+ if ((newtemp || respondstr) && usbComTxAvailable() >= 64)
+ {
+ const char *cp;
+ uint8 XDATA response[64];
+ uint8 responseLength = 0;
+
+ decimals = (air_temp_c & 0xf) * 100;
+ responseLength = sprintf(response, "%d.%02d", air_temp_c / 16, decimals / 16);
+ response[responseLength++] = ',';
+ for (i = 0; i < 8; i++) {
+ response[responseLength++] = nibbleToAscii(DS1820_addr[i] >> 4);
+ response[responseLength++] = nibbleToAscii(DS1820_addr[i]);
+ }
+ response[responseLength++] = ',';
+ i = sizeof(response) - responseLength - 2;
+
+ if (respondstr) {
+ for (cp = respondstr; *respondstr && i--; respondstr++) {
+ response[responseLength++] = *cp;
+ }
+ }
+ respondstr = NULL;
+ response[responseLength++] = '\r';
+ response[responseLength++] = '\n';
+ usbComTxSend(response, responseLength);
+ }
+}
+
+void main()
+{
+ systemInit();
+
+ usbInit();
+ setup_DS1820();
+ while(1)
+ {
+ boardService();
+ updateLeds();
+ usbComService();
+ handleOneWire();
+ }
+}
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529 apps/example_onewire/onewire.c
@@ -0,0 +1,529 @@
+/*
+Copyright (c) 2012, Russell Nelson
+
+Adapted from http://www.pjrc.com/teensy/td_libs_OneWire.html
+for the Wixel. Permissions granted by the license below.
+
+Copyright (c) 2007, Jim Studt
+
+
+Version 2.0: Modifications by Paul Stoffregen, January 2010:
+http://www.pjrc.com/teensy/td_libs_OneWire.html
+ Search fix from Robin James
+ http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
+ Use direct optimized I/O in all cases
+ Disable interrupts during timing critical sections
+ (this solves many random communication errors)
+ Disable interrupts during read-modify-write I/O
+ Reduce RAM consumption by eliminating unnecessary
+ variables and trimming many to 8 bits
+ Optimize both crc8 - table version moved to flash
+
+Modified to work with larger numbers of devices - avoids loop.
+Tested in Arduino 11 alpha with 12 sensors.
+26 Sept 2008 -- Robin James
+http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295/27#27
+
+Updated to work with arduino-0008 and to include skip() as of
+2007/07/06. --RJL20
+
+Modified to calculate the 8-bit CRC directly, avoiding the need for
+the 256-byte lookup table to be loaded in RAM. Tested in arduino-0010
+-- Tom Pollard, Jan 23, 2008
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Much of the code was inspired by Derek Yerger's code, though I don't
+think much of that remains. In any event that was..
+ (copyleft) 2006 by Derek Yerger - Free to distribute freely.
+
+The CRC code was excerpted and inspired by the Dallas Semiconductor
+sample code bearing this copyright.
+//---------------------------------------------------------------------------
+// Copyright (C) 2000 Dallas Semiconductor Corporation, All Rights Reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL DALLAS SEMICONDUCTOR BE LIABLE FOR ANY CLAIM, DAMAGES
+// OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+//
+// Except as contained in this notice, the name of Dallas Semiconductor
+// shall not be used except as stated in the Dallas Semiconductor
+// Branding Policy.
+//--------------------------------------------------------------------------
+*/
+
+#include <cc2511_map.h>
+#include <board.h>
+#include <time.h>
+#include <gpio.h>
+#include "onewire.h"
+#include "onewire_ports.h"
+
+// pull these two in from onewire_ports
+// means "pin", not mask; 0 <= mask <= 7
+#define mask 0
+#define reg 0
+
+// Don't need these
+#define cli()
+#define sei()
+
+void onewire_start(void)
+{
+#if ONEWIRE_SEARCH
+ onewire_reset_search();
+#endif
+}
+
+
+
+// ************************************************************
+// THESE ARE MACROS, NOT FUNCTIONS. PORT AND PIN ARE HARD-CODED.
+// ************************************************************
+
+#define XDIRECT_READ(base, pin) (P##base##_##pin)
+#define XDIRECT_MODE_INPUT(base, pin) (P##base##DIR &= ~(1<<pin))
+#define XDIRECT_MODE_OUTPUT(base, pin) (P##base##DIR |= (1<<pin))
+#define XDIRECT_WRITE_LOW(base, pin) (P##base##_##pin = 0);
+#define XDIRECT_WRITE_HIGH(base, pin) (P##base##_##pin = 1)
+
+// Required by the C preprocessor to get the macros rescanned.
+#define DIRECT_READ(base, pin) XDIRECT_READ(base, pin)
+#define DIRECT_MODE_INPUT(base, pin) XDIRECT_MODE_INPUT(base, pin)
+#define DIRECT_MODE_OUTPUT(base, pin) XDIRECT_MODE_OUTPUT(base, pin)
+#define DIRECT_WRITE_LOW(base, pin) XDIRECT_WRITE_LOW(base, pin)
+#define DIRECT_WRITE_HIGH(base, pin) XDIRECT_WRITE_HIGH(base, pin)
+
+
+
+// Perform the onewire reset function. We will wait up to 250uS for
+// the bus to come high, if it doesn't then it is broken or shorted
+// and we return a 0;
+//
+// Returns 1 if a device asserted a presence pulse, 0 otherwise.
+//
+uint8_t onewire_reset(void)
+{
+ uint8_t r;
+ uint8_t retries = 125;
+
+ cli();
+ DIRECT_MODE_INPUT(reg, mask);
+ sei();
+ // wait until the wire is high... just in case
+ do {
+ if (--retries == 0) return 0;
+ delayMicroseconds(2);
+ } while ( !DIRECT_READ(reg, mask));
+
+ cli();
+ DIRECT_MODE_OUTPUT(reg, mask); // drive output low
+ // had to reverse the order of these. Compiler was not
+ // generating any code for the write (!)
+ DIRECT_WRITE_LOW(reg, mask);
+ sei();
+ delayMicroseconds(500);
+ cli();
+ DIRECT_MODE_INPUT(reg, mask); // allow it to float
+ delayMicroseconds(80);
+ r = !DIRECT_READ(reg, mask);
+ LED_YELLOW_TOGGLE();
+ sei();
+ delayMicroseconds(420);
+ return r;
+}
+
+//
+// Write a bit. Port and bit is used to cut lookup time and provide
+// more certain timing.
+//
+void onewire_write_bit(uint8_t v)
+{
+ if (v & 1) {
+ cli();
+ DIRECT_WRITE_LOW(reg, mask);
+ DIRECT_MODE_OUTPUT(reg, mask); // drive output low
+ delayMicroseconds(10);
+ DIRECT_WRITE_HIGH(reg, mask); // drive output high
+ sei();
+ delayMicroseconds(55);
+ } else {
+ cli();
+ DIRECT_WRITE_LOW(reg, mask);
+ DIRECT_MODE_OUTPUT(reg, mask); // drive output low
+ delayMicroseconds(65);
+ DIRECT_WRITE_HIGH(reg, mask); // drive output high
+ sei();
+ delayMicroseconds(5);
+ }
+}
+
+//
+// Read a bit. Port and bit is used to cut lookup time and provide
+// more certain timing.
+//
+uint8_t onewire_read_bit(void)
+{
+ uint8_t r;
+
+ cli();
+ DIRECT_MODE_OUTPUT(reg, mask);
+ DIRECT_WRITE_LOW(reg, mask);
+ delayMicroseconds(3);
+ DIRECT_MODE_INPUT(reg, mask); // let pin float, pull up will raise
+ delayMicroseconds(9);
+ r = DIRECT_READ(reg, mask);
+ sei();
+ delayMicroseconds(53);
+ return r;
+}
+
+//
+// Write a byte. The writing code uses the active drivers to raise the
+// pin high, if you need power after the write (e.g. DS18S20 in
+// parasite power mode) then set 'power' to 1, otherwise the pin will
+// go tri-state at the end of the write to avoid heating in a short or
+// other mishap.
+//
+void onewire_write(uint8_t v, uint8_t power) {
+ uint8_t bitMask;
+
+ for (bitMask = 0x01; bitMask; bitMask <<= 1) {
+ onewire_write_bit( (bitMask & v)?1:0);
+ }
+ if ( !power) {
+ cli();
+ DIRECT_MODE_INPUT(reg, mask);
+ DIRECT_WRITE_LOW(reg, mask);
+ sei();
+ }
+}
+
+//
+// Read a byte
+//
+uint8_t onewire_read() {
+ uint8_t bitMask;
+ uint8_t r = 0;
+
+ for (bitMask = 0x01; bitMask; bitMask <<= 1) {
+ if ( onewire_read_bit()) r |= bitMask;
+ }
+ return r;
+}
+
+//
+// Do a ROM select
+//
+void onewire_select( uint8_t rom[8])
+{
+ int i;
+
+ onewire_write(0x55,0); // Choose ROM
+
+ for( i = 0; i < 8; i++) onewire_write(rom[i],0);
+}
+
+//
+// Do a ROM skip
+//
+void onewire_skip()
+{
+ onewire_write(0xCC,0); // Skip ROM
+}
+
+void onewire_depower()
+{
+ cli();
+ DIRECT_MODE_INPUT(reg, mask);
+ sei();
+}
+
+#if ONEWIRE_SEARCH
+
+// global search state
+uint8 ROM_NO[8];
+uint8_t LastDiscrepancy;
+uint8_t LastFamilyDiscrepancy;
+uint8_t LastDeviceFlag;
+
+//
+// You need to use this function to start a search again from the beginning.
+// You do not need to do it for the first search, though you could.
+//
+void onewire_reset_search()
+ {
+ int i;
+ // reset the search state
+ LastDiscrepancy = 0;
+ LastDeviceFlag = FALSE;
+ LastFamilyDiscrepancy = 0;
+ for(i = 7; ; i--)
+ {
+ ROM_NO[i] = 0;
+ if ( i == 0) break;
+ }
+ }
+
+//
+// Perform a search. If this function returns a '1' then it has
+// enumerated the next device and you may retrieve the ROM from the
+// OneWire::address variable. If there are no devices, no further
+// devices, or something horrible happens in the middle of the
+// enumeration then a 0 is returned. If a new device is found then
+// its address is copied to newAddr. Use OneWire::reset_search() to
+// start over.
+//
+// --- Replaced by the one from the Dallas Semiconductor web site ---
+//--------------------------------------------------------------------------
+// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
+// search state.
+// Return TRUE : device found, ROM number in ROM_NO buffer
+// FALSE : device not found, end of search
+//
+uint8_t onewire_search(uint8_t *newAddr)
+{
+ uint8_t id_bit_number;
+ uint8_t last_zero, rom_byte_number, search_result;
+ uint8_t id_bit, cmp_id_bit;
+ int i;
+
+ unsigned char rom_byte_mask, search_direction;
+
+ // initialize for search
+ id_bit_number = 1;
+ last_zero = 0;
+ rom_byte_number = 0;
+ rom_byte_mask = 1;
+ search_result = 0;
+
+ // if the last call was not the last one
+ if (!LastDeviceFlag)
+ {
+ // 1-Wire reset
+ if (!onewire_reset())
+ {
+ // reset the search
+ LastDiscrepancy = 0;
+ LastDeviceFlag = FALSE;
+ LastFamilyDiscrepancy = 0;
+ return FALSE;
+ }
+
+ // issue the search command
+ onewire_write(0xF0,0);
+
+ // loop to do the search
+ do
+ {
+ // read a bit and its complement
+ id_bit = onewire_read_bit();
+ cmp_id_bit = onewire_read_bit();
+
+ // check for no devices on 1-wire
+ if ((id_bit == 1) && (cmp_id_bit == 1))
+ break;
+ else
+ {
+ // all devices coupled have 0 or 1
+ if (id_bit != cmp_id_bit)
+ search_direction = id_bit; // bit write value for search
+ else
+ {
+ // if this discrepancy if before the Last Discrepancy
+ // on a previous next then pick the same as last time
+ if (id_bit_number < LastDiscrepancy)
+ search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
+ else
+ // if equal to last pick 1, if not then pick 0
+ search_direction = (id_bit_number == LastDiscrepancy);
+
+ // if 0 was picked then record its position in LastZero
+ if (search_direction == 0)
+ {
+ last_zero = id_bit_number;
+
+ // check for Last discrepancy in family
+ if (last_zero < 9)
+ 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_NO[rom_byte_number] |= rom_byte_mask;
+ else
+ ROM_NO[rom_byte_number] &= ~rom_byte_mask;
+
+ // serial number search direction write bit
+ onewire_write_bit(search_direction);
+
+ // increment the byte counter id_bit_number
+ // and shift the mask rom_byte_mask
+ id_bit_number++;
+ rom_byte_mask <<= 1;
+
+ // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
+ if (rom_byte_mask == 0)
+ {
+ 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 (!(id_bit_number < 65))
+ {
+ // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
+ LastDiscrepancy = last_zero;
+
+ // check for last device
+ if (LastDiscrepancy == 0)
+ LastDeviceFlag = TRUE;
+
+ search_result = TRUE;
+ }
+ }
+
+ // if no device found then reset counters so next 'search' will be like a first
+ if (!search_result || !ROM_NO[0])
+ {
+ LastDiscrepancy = 0;
+ LastDeviceFlag = FALSE;
+ LastFamilyDiscrepancy = 0;
+ search_result = FALSE;
+ }
+ for (i = 0; i < 8; i++) newAddr[i] = ROM_NO[i];
+ return search_result;
+ }
+
+#endif
+
+#if ONEWIRE_CRC
+// The 1-Wire CRC scheme is described in Maxim Application Note 27:
+// "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
+//
+
+#if ONEWIRE_CRC8_TABLE
+// This table comes from Dallas sample code where it is freely reusable,
+// though Copyright (C) 2000 Dallas Semiconductor Corporation
+static const uint8_t CODE 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};
+
+//
+// Compute a Dallas Semiconductor 8 bit CRC. These show up in the ROM
+// and the registers. (note: this might better be done without to
+// table, it would probably be smaller and certainly fast enough
+// compared to all those delayMicrosecond() calls. But I got
+// confused, so I use this table from the examples.)
+//
+uint8_t onewire_crc8( uint8_t *addr, uint8_t len)
+{
+ uint8_t crc = 0;
+
+ while (len--) {
+ crc = dscrc_table[crc ^ *addr++];
+ }
+ return crc;
+}
+#else
+//
+// Compute a Dallas Semiconductor 8 bit CRC directly.
+//
+uint8_t onewire_crc8( uint8_t *addr, uint8_t len)
+{
+ uint8_t crc = 0;
+ uint8_t i;
+
+ while (len--) {
+ uint8_t inbyte = *addr++;
+ for (i = 8; i; i--) {
+ uint8_t mix = (crc ^ inbyte) & 0x01;
+ crc >>= 1;
+ if (mix) crc ^= 0x8C;
+ inbyte >>= 1;
+ }
+ }
+ return crc;
+}
+#endif
+
+#if ONEWIRE_CRC16
+static short oddparity[16] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };
+
+//
+// Compute a Dallas Semiconductor 16 bit CRC. I have never seen one of
+// these, but here it is.
+//
+unsigned short onewire_crc16(unsigned short *data, unsigned short len)
+{
+ unsigned short i;
+ unsigned short crc = 0;
+
+ for ( i = 0; i < len; i++) {
+ unsigned short cdata = data[len];
+
+ cdata = (cdata ^ (crc & 0xff)) & 0xff;
+ crc >>= 8;
+
+ if (oddparity[cdata & 0xf] ^ oddparity[cdata >> 4]) crc ^= 0xc001;
+
+ cdata <<= 6;
+ crc ^= cdata;
+ cdata <<= 1;
+ crc ^= cdata;
+ }
+ return crc;
+}
+#endif
+
+#endif
View
93 apps/example_onewire/onewire.h
@@ -0,0 +1,93 @@
+#ifndef OneWire_h
+#define OneWire_h
+
+typedef uint8 uint8_t; // try not to modify the Arduino code more than we have to.
+
+// you can exclude onewire_search by defining that to 0
+#ifndef ONEWIRE_SEARCH
+#define ONEWIRE_SEARCH 1
+#endif
+
+// You can exclude CRC checks altogether by defining this to 0
+#ifndef ONEWIRE_CRC
+#define ONEWIRE_CRC 1
+#endif
+
+// Select the table-lookup method of computing the 8-bit CRC
+// by setting this to 1. The lookup table no longer consumes
+// limited RAM, but enlarges total code size by about 250 bytes
+#ifndef ONEWIRE_CRC8_TABLE
+#define ONEWIRE_CRC8_TABLE 0
+#endif
+
+// You can allow 16-bit CRC checks by defining this to 1
+// (Note that ONEWIRE_CRC must also be 1.)
+#ifndef ONEWIRE_CRC16
+#define ONEWIRE_CRC16 0
+#endif
+
+#define FALSE 0
+#define TRUE 1
+
+ void onewire_start( void );
+
+ // Perform a 1-Wire reset cycle. Returns 1 if a device responds
+ // with a presence pulse. Returns 0 if there is no device or the
+ // bus is shorted or otherwise held low for more than 250uS
+ uint8_t onewire_reset(void);
+
+ // Issue a 1-Wire rom select command, you do the reset first.
+ void onewire_select( uint8_t rom[8]);
+
+ // Issue a 1-Wire rom skip command, to address all on bus.
+ void onewire_skip(void);
+
+ // Write a byte. If 'power' is one then the wire is held high at
+ // the end for parasitically powered devices. You are responsible
+ // for eventually depowering it by calling depower() or doing
+ // another read or write.
+ void onewire_write(uint8_t v, uint8_t power);
+
+ // Read a byte.
+ uint8_t onewire_read(void);
+
+ // Write a bit. The bus is always left powered at the end, see
+ // note in write() about that.
+ void onewire_write_bit(uint8_t v);
+
+ // Read a bit.
+ uint8_t onewire_read_bit(void);
+
+ // Stop forcing power onto the bus. You only need to do this if
+ // you used the 'power' flag to write() or used a write_bit() call
+ // and aren't about to do another read or write. You would rather
+ // not leave this powered if you don't have to, just in case
+ // someone shorts your bus.
+ void onewire_depower(void);
+
+#if ONEWIRE_SEARCH
+ // Clear the search state so that if will start from the beginning again.
+ void onewire_reset_search();
+
+ // Look for the next device. Returns 1 if a new address has been
+ // returned. A zero might mean that the bus is shorted, there are
+ // no devices, or you have already retrieved all of them. It
+ // might be a good idea to check the CRC to make sure you didn't
+ // get garbage. The order is deterministic. You will always get
+ // the same devices in the same order.
+ uint8_t onewire_search(uint8_t *newAddr);
+#endif
+
+#if ONEWIRE_CRC
+ // Compute a Dallas Semiconductor 8 bit CRC, these are used in the
+ // ROM and scratchpad registers.
+ uint8_t onewire_crc8( uint8_t *addr, uint8_t len);
+
+#if ONEWIRE_CRC16
+ // Compute a Dallas Semiconductor 16 bit CRC. Maybe. I don't have
+ // any devices that use this so this might be wrong. I just copied
+ // it from their sample code.
+ static unsigned short onewire_crc16(unsigned short *data, unsigned short len);
+#endif
+#endif
+#endif
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