466 lines
No EOL
14 KiB
C
466 lines
No EOL
14 KiB
C
#include "onewire.h"
|
|
|
|
// global search state
|
|
static unsigned char ROM_NO[ONEWIRE_NUM][8];
|
|
static uint8_t LastDiscrepancy[ONEWIRE_NUM];
|
|
static uint8_t LastFamilyDiscrepancy[ONEWIRE_NUM];
|
|
static uint8_t LastDeviceFlag[ONEWIRE_NUM];
|
|
|
|
void onewire_init(uint8_t pin)
|
|
{
|
|
gpio_enable(pin, GPIO_INPUT);
|
|
onewire_reset_search(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(uint8_t pin)
|
|
{
|
|
uint8_t r;
|
|
uint8_t retries = 125;
|
|
|
|
noInterrupts();
|
|
DIRECT_MODE_INPUT(pin);
|
|
interrupts();
|
|
// wait until the wire is high... just in case
|
|
do {
|
|
if (--retries == 0) return 0;
|
|
delayMicroseconds(2);
|
|
} while ( !DIRECT_READ(pin));
|
|
|
|
noInterrupts();
|
|
DIRECT_WRITE_LOW(pin);
|
|
DIRECT_MODE_OUTPUT(pin); // drive output low
|
|
interrupts();
|
|
delayMicroseconds(480);
|
|
noInterrupts();
|
|
DIRECT_MODE_INPUT(pin); // allow it to float
|
|
delayMicroseconds(70);
|
|
r = !DIRECT_READ(pin);
|
|
interrupts();
|
|
delayMicroseconds(410);
|
|
return r;
|
|
}
|
|
|
|
// Write a bit. Port and bit is used to cut lookup time and provide
|
|
// more certain timing.
|
|
//
|
|
static void onewire_write_bit(uint8_t pin, uint8_t v)
|
|
{
|
|
if (v & 1) {
|
|
noInterrupts();
|
|
DIRECT_WRITE_LOW(pin);
|
|
DIRECT_MODE_OUTPUT(pin); // drive output low
|
|
delayMicroseconds(10);
|
|
DIRECT_WRITE_HIGH(pin); // drive output high
|
|
interrupts();
|
|
delayMicroseconds(55);
|
|
} else {
|
|
noInterrupts();
|
|
DIRECT_WRITE_LOW(pin);
|
|
DIRECT_MODE_OUTPUT(pin); // drive output low
|
|
delayMicroseconds(65);
|
|
DIRECT_WRITE_HIGH(pin); // drive output high
|
|
interrupts();
|
|
delayMicroseconds(5);
|
|
}
|
|
}
|
|
|
|
// Read a bit. Port and bit is used to cut lookup time and provide
|
|
// more certain timing.
|
|
//
|
|
static uint8_t onewire_read_bit(uint8_t pin)
|
|
{
|
|
uint8_t r;
|
|
|
|
noInterrupts();
|
|
DIRECT_MODE_OUTPUT(pin);
|
|
DIRECT_WRITE_LOW(pin);
|
|
delayMicroseconds(3);
|
|
DIRECT_MODE_INPUT(pin); // let pin float, pull up will raise
|
|
delayMicroseconds(10);
|
|
r = DIRECT_READ(pin);
|
|
interrupts();
|
|
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 pin, uint8_t v, uint8_t power /* = 0 */) {
|
|
uint8_t bitMask;
|
|
|
|
for (bitMask = 0x01; bitMask; bitMask <<= 1) {
|
|
onewire_write_bit(pin, (bitMask & v)?1:0);
|
|
}
|
|
if ( !power) {
|
|
noInterrupts();
|
|
DIRECT_MODE_INPUT(pin);
|
|
DIRECT_WRITE_LOW(pin);
|
|
interrupts();
|
|
}
|
|
}
|
|
|
|
void onewire_write_bytes(uint8_t pin, const uint8_t *buf, uint16_t count, bool power /* = 0 */) {
|
|
uint16_t i;
|
|
for (i = 0 ; i < count ; i++)
|
|
onewire_write(pin, buf[i], ONEWIRE_DEFAULT_POWER);
|
|
if (!power) {
|
|
noInterrupts();
|
|
DIRECT_MODE_INPUT(pin);
|
|
DIRECT_WRITE_LOW(pin);
|
|
interrupts();
|
|
}
|
|
}
|
|
|
|
// Read a byte
|
|
//
|
|
uint8_t onewire_read(uint8_t pin) {
|
|
uint8_t bitMask;
|
|
uint8_t r = 0;
|
|
|
|
for (bitMask = 0x01; bitMask; bitMask <<= 1) {
|
|
if (onewire_read_bit(pin)) r |= bitMask;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
void onewire_read_bytes(uint8_t pin, uint8_t *buf, uint16_t count) {
|
|
uint16_t i;
|
|
for (i = 0 ; i < count ; i++)
|
|
buf[i] = onewire_read(pin);
|
|
}
|
|
|
|
// Do a ROM select
|
|
//
|
|
void onewire_select(uint8_t pin, const uint8_t rom[8])
|
|
{
|
|
uint8_t i;
|
|
|
|
onewire_write(pin, 0x55, ONEWIRE_DEFAULT_POWER); // Choose ROM
|
|
|
|
for (i = 0; i < 8; i++) onewire_write(pin, rom[i], ONEWIRE_DEFAULT_POWER);
|
|
}
|
|
|
|
// Do a ROM skip
|
|
//
|
|
void onewire_skip(uint8_t pin)
|
|
{
|
|
onewire_write(pin, 0xCC, ONEWIRE_DEFAULT_POWER); // Skip ROM
|
|
}
|
|
|
|
void onewire_depower(uint8_t pin)
|
|
{
|
|
noInterrupts();
|
|
DIRECT_MODE_INPUT(pin);
|
|
interrupts();
|
|
}
|
|
|
|
// 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(uint8_t pin)
|
|
{
|
|
// reset the search state
|
|
LastDiscrepancy[pin] = 0;
|
|
LastDeviceFlag[pin] = 0;
|
|
LastFamilyDiscrepancy[pin] = 0;
|
|
int i;
|
|
for(i = 7; ; i--) {
|
|
ROM_NO[pin][i] = 0;
|
|
if ( i == 0) break;
|
|
}
|
|
}
|
|
|
|
// Setup the search to find the device type 'family_code' on the next call
|
|
// to search(*newAddr) if it is present.
|
|
//
|
|
void onewire_target_search(uint8_t pin, uint8_t family_code)
|
|
{
|
|
// set the search state to find SearchFamily type devices
|
|
ROM_NO[pin][0] = family_code;
|
|
uint8_t i;
|
|
for (i = 1; i < 8; i++)
|
|
ROM_NO[pin][i] = 0;
|
|
LastDiscrepancy[pin] = 64;
|
|
LastFamilyDiscrepancy[pin] = 0;
|
|
LastDeviceFlag[pin] = 0;
|
|
}
|
|
|
|
// 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 1 : device found, ROM number in ROM_NO buffer
|
|
// 0 : device not found, end of search
|
|
//
|
|
uint8_t onewire_search(uint8_t pin, uint8_t *newAddr)
|
|
{
|
|
uint8_t id_bit_number;
|
|
uint8_t last_zero, rom_byte_number, search_result;
|
|
uint8_t id_bit, cmp_id_bit;
|
|
|
|
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[pin])
|
|
{
|
|
// 1-Wire reset
|
|
if (!onewire_reset(pin))
|
|
{
|
|
// reset the search
|
|
LastDiscrepancy[pin] = 0;
|
|
LastDeviceFlag[pin] = 0;
|
|
LastFamilyDiscrepancy[pin] = 0;
|
|
return 0;
|
|
}
|
|
|
|
// issue the search command
|
|
onewire_write(pin, 0xF0, ONEWIRE_DEFAULT_POWER);
|
|
|
|
// loop to do the search
|
|
do
|
|
{
|
|
// read a bit and its complement
|
|
id_bit = onewire_read_bit(pin);
|
|
cmp_id_bit = onewire_read_bit(pin);
|
|
|
|
// 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[pin])
|
|
search_direction = ((ROM_NO[pin][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[pin]);
|
|
|
|
// 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[pin] = 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[pin][rom_byte_number] |= rom_byte_mask;
|
|
else
|
|
ROM_NO[pin][rom_byte_number] &= ~rom_byte_mask;
|
|
|
|
// serial number search direction write bit
|
|
onewire_write_bit(pin, 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[pin] = last_zero;
|
|
|
|
// check for last device
|
|
if (LastDiscrepancy[pin] == 0)
|
|
LastDeviceFlag[pin] = 1;
|
|
|
|
search_result = 1;
|
|
}
|
|
}
|
|
|
|
// if no device found then reset counters so next 'search' will be like a first
|
|
if (!search_result || !ROM_NO[pin][0])
|
|
{
|
|
LastDiscrepancy[pin] = 0;
|
|
LastDeviceFlag[pin] = 0;
|
|
LastFamilyDiscrepancy[pin] = 0;
|
|
search_result = 0;
|
|
}
|
|
else
|
|
{
|
|
for (rom_byte_number = 0; rom_byte_number < 8; rom_byte_number++)
|
|
{
|
|
newAddr[rom_byte_number] = ROM_NO[pin][rom_byte_number];
|
|
//printf("Ok I found something at %d - %x...\n",rom_byte_number, newAddr[rom_byte_number]);
|
|
}
|
|
}
|
|
return search_result;
|
|
}
|
|
|
|
// 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 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};
|
|
|
|
#ifndef pgm_read_byte
|
|
#define pgm_read_byte(addr) (*(const uint8_t *)(addr))
|
|
#endif
|
|
|
|
//
|
|
// 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(const uint8_t *addr, uint8_t len)
|
|
{
|
|
uint8_t crc = 0;
|
|
|
|
while (len--) {
|
|
crc = pgm_read_byte(dscrc_table + (crc ^ *addr++));
|
|
}
|
|
return crc;
|
|
}
|
|
#else
|
|
//
|
|
// Compute a Dallas Semiconductor 8 bit CRC directly.
|
|
// this is much slower, but much smaller, than the lookup table.
|
|
//
|
|
uint8_t onewire_crc8(const uint8_t *addr, uint8_t len)
|
|
{
|
|
uint8_t crc = 0;
|
|
|
|
while (len--) {
|
|
uint8_t inbyte = *addr++;
|
|
uint8_t i;
|
|
for (i = 8; i; i--) {
|
|
uint8_t mix = (crc ^ inbyte) & 0x01;
|
|
crc >>= 1;
|
|
if (mix) crc ^= 0x8C;
|
|
inbyte >>= 1;
|
|
}
|
|
}
|
|
return crc;
|
|
}
|
|
#endif
|
|
|
|
// Compute the 1-Wire CRC16 and compare it against the received CRC.
|
|
// Example usage (reading a DS2408):
|
|
// // Put everything in a buffer so we can compute the CRC easily.
|
|
// uint8_t buf[13];
|
|
// buf[0] = 0xF0; // Read PIO Registers
|
|
// buf[1] = 0x88; // LSB address
|
|
// buf[2] = 0x00; // MSB address
|
|
// WriteBytes(net, buf, 3); // Write 3 cmd bytes
|
|
// ReadBytes(net, buf+3, 10); // Read 6 data bytes, 2 0xFF, 2 CRC16
|
|
// if (!CheckCRC16(buf, 11, &buf[11])) {
|
|
// // Handle error.
|
|
// }
|
|
//
|
|
// @param input - Array of bytes to checksum.
|
|
// @param len - How many bytes to use.
|
|
// @param inverted_crc - The two CRC16 bytes in the received data.
|
|
// This should just point into the received data,
|
|
// *not* at a 16-bit integer.
|
|
// @param crc - The crc starting value (optional)
|
|
// @return 1, iff the CRC matches.
|
|
bool onewire_check_crc16(const uint8_t* input, uint16_t len, const uint8_t* inverted_crc, uint16_t crc)
|
|
{
|
|
crc = ~onewire_crc16(input, len, crc);
|
|
return (crc & 0xFF) == inverted_crc[0] && (crc >> 8) == inverted_crc[1];
|
|
}
|
|
|
|
// Compute a Dallas Semiconductor 16 bit CRC. This is required to check
|
|
// the integrity of data received from many 1-Wire devices. Note that the
|
|
// CRC computed here is *not* what you'll get from the 1-Wire network,
|
|
// for two reasons:
|
|
// 1) The CRC is transmitted bitwise inverted.
|
|
// 2) Depending on the endian-ness of your processor, the binary
|
|
// representation of the two-byte return value may have a different
|
|
// byte order than the two bytes you get from 1-Wire.
|
|
// @param input - Array of bytes to checksum.
|
|
// @param len - How many bytes to use.
|
|
// @param crc - The crc starting value (optional)
|
|
// @return The CRC16, as defined by Dallas Semiconductor.
|
|
uint16_t onewire_crc16(const uint8_t* input, uint16_t len, uint16_t crc)
|
|
{
|
|
static const uint8_t oddparity[16] =
|
|
{ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };
|
|
|
|
uint16_t i;
|
|
for (i = 0 ; i < len ; i++) {
|
|
// Even though we're just copying a byte from the input,
|
|
// we'll be doing 16-bit computation with it.
|
|
uint16_t cdata = input[i];
|
|
cdata = (cdata ^ crc) & 0xff;
|
|
crc >>= 8;
|
|
|
|
if (oddparity[cdata & 0x0F] ^ oddparity[cdata >> 4])
|
|
crc ^= 0xC001;
|
|
|
|
cdata <<= 6;
|
|
crc ^= cdata;
|
|
cdata <<= 1;
|
|
crc ^= cdata;
|
|
}
|
|
return crc;
|
|
} |