static void selectdevbyidx(int idx) {
if(idx < numowdevices) {
resetbus();
xferbyte(OW_MATCH_ROM);
for( int idloop = 0; idloop < 8; idloop++ ) { // Send ROM device ID
xferbyte(owdeviceids[idx][idloop]);
}
}
}
int OneWire_PerformTemperatureConversion(void) {
uint8_t scratch[9];
if(resetbus()) {
xferbyte(OW_SKIP_ROM); // All devices on the bus are addressed here
xferbyte(OW_CONVERT_T);
setpin1();
BusyWait8(94000<<3); // For 9-bit resolution
for( int i = 0; i < numowdevices; i++ ) {
selectdevbyidx(i);
xferbyte(OW_READ_SCRATCHPAD);
for(uint32_t iter=0; iter<2; iter++) { // Only read two bytes
scratch[iter] = xferbyte(0xff);
//printf("%02x ",scratch[iter]);
}
int16_t tmp = scratch[1]<<8 | scratch[0];
devreadout[i] = tmp;
}
} else {
BusyWait8(94000<<3); // Maintain timing if no sensors are found for the time being
}
return numowdevices;
}
static int32_t OneWire_Work(void) {
static uint8_t mystate = 0;
uint8_t scratch[9];
int32_t retval = 0;
if (mystate == 0) {
uint32_t save = VIC_DisableIRQ();
if (resetbus()) {
xferbyte(OW_SKIP_ROM); // All devices on the bus are addressed here
xferbyte(OW_CONVERT_T);
setpin1();
//retval = TICKS_MS(94); // For 9-bit resolution
retval = TICKS_MS(100); // TC interface needs max 100ms to be ready
mystate++;
}
VIC_RestoreIRQ( save );
} else if (mystate == 1) {
for (int i = 0; i < numowdevices; i++) {
uint32_t save = VIC_DisableIRQ();
selectdevbyidx(i);
xferbyte(OW_READ_SCRATCHPAD);
for (uint32_t iter = 0; iter < 4; iter++) { // Read four bytes
scratch[iter] = xferbyte(0xff);
}
VIC_RestoreIRQ(save);
int16_t tmp = scratch[1]<<8 | scratch[0];
devreadout[i] = tmp;
tmp = scratch[3]<<8 | scratch[2];
extrareadout[i] = tmp;
}
mystate = 0;
} else {
retval = -1;
}
return retval;
}
//--------------------------------------------------------------------------
// 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
//
static int OWSearch()
{
int id_bit_number;
int last_zero, rom_byte_number, search_result;
int id_bit, cmp_id_bit;
uint8_t 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;
crc8 = 0;
// if the last call was not the last one
if (!LastDeviceFlag) {
// 1-Wire reset
if (!resetbus()) { // No devices found
// reset the search
LastDiscrepancy = 0;
LastDeviceFlag = false;
LastFamilyDiscrepancy = 0;
return false;
}
// issue the search command
xferbyte( OW_SEARCH_ROM );
// loop to do the search
do {
// read a bit and its complement
id_bit = xferbit( true );
cmp_id_bit = xferbit( true );
// 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
xferbit(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) {
docrc8(ROM_NO[rom_byte_number]); // accumulate the CRC
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) || (crc8 != 0))) {
// 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;
}
return search_result;
}
