static void ds18x20SendByte(uint8_t byte)
{
uint8_t i;
for (i = 0; i < 8; i++)
ds18x20SendBit(byte & (1<<i));
return;
}
static void ds18x20SendByte(uint8_t byte)
{
uint8_t i;
for (i = 0; i < 8; i++) {
ds18x20SendBit(byte & 0x01);
byte >>= 1;
}
return;
}
static uint8_t ds18x20SearchRom(uint8_t *bitPattern, uint8_t lastDeviation)
{
uint8_t currBit;
uint8_t newDeviation = 0;
uint8_t bitMask = 0x01;
uint8_t bitA;
uint8_t bitB;
// Send SEARCH ROM command on the bus
ds18x20SendByte(DS18X20_CMD_SEARCH_ROM);
// Walk through all 64 bits
for (currBit = 0; currBit < DS18X20_ID_LEN * 8; currBit++)
{
// Read bit from bus twice.
bitA = ds18x20GetBit();
bitB = ds18x20GetBit();
if (bitA && bitB) { // Both bits 1 = ERROR
return 0xFF;
} else if (!(bitA || bitB)) { // Both bits 0
if (currBit == lastDeviation) { // Select 1 if device has been selected
*bitPattern |= bitMask;
} else if (currBit > lastDeviation) { // Select 0 if no, and remember device
(*bitPattern) &= ~bitMask;
newDeviation = currBit;
} else if (!(*bitPattern & bitMask)) { // Otherwise just remember device
newDeviation = currBit;
}
} else { // Bits differ
if (bitA)
*bitPattern |= bitMask;
else
*bitPattern &= ~bitMask;
}
// Send the selected bit to the bus.
ds18x20SendBit(*bitPattern & bitMask);
// Adjust bitMask and bitPattern pointer.
bitMask <<= 1;
if (!bitMask)
{
bitMask = 0x01;
bitPattern++;
}
}
return newDeviation;
}
