void dallasWaitUntilDone(void)
{
//timerPause(6);
// wait until we recieve a one
cli();
while(!dallasReadBit());
sei();
}
u08 dallasReadByte(void)
{
u08 i;
u08 byte = 0;
cli();
// read all 8 bits
for(i=0;i<8;i++)
{
if (dallasReadBit())
byte |= 0x01<<i;
// allow a us delay between each read
dallasDelayUs(1);
}
sei();
return byte;
}
u08 dallasFindNextDevice(dallas_rom_id_T* rom_id)
{
u08 bit;
u08 i = 0;
u08 bit_index = 1;
u08 byte_index = 0;
u08 bit_mask = 1;
u08 discrep_marker = 0;
// reset the CRC
dallas_crc = 0;
if (done_flag || dallasReset() != DALLAS_PRESENCE)
{
// no more devices parts detected
return FALSE;
}
// send search ROM command
dallasWriteByte(DALLAS_SEARCH_ROM);
// loop until through all 8 ROM bytes
while(byte_index<8)
{
// read line 2 times to determine status of devices
// 00 - devices connected to bus with conflicting bits
// 01 - all devices have a 0 in this position
// 10 - all devices ahve a 1 in this position
// 11 - there are no devices connected to bus
i = 0;
cli();
if (dallasReadBit())
i = 2; // store the msb if 1
//delay_us(120);
delay(120);
if (dallasReadBit())
i |= 1; // store the lsb if 1
sei();
if (i==3)
{
// there are no devices on the 1-wire
break;
}
else
{
if (i>0)
{
// all devices coupled have 0 or 1
// shift 1 to determine if the msb is 0 or 1
bit = i>>1;
}
else
{
// if this discrepancy is before the last discrepancy on a
// previous FindNextDevice then pick the same as last time
if (bit_index<last_discrep)
bit = ((rom_id->byte[byte_index] & bit_mask) > 0);
else
bit = (bit_index==last_discrep);
// if 0 was picked then record position with bit mask
if (!bit)
discrep_marker = bit_index;
}
// isolate bit in rom_id->byte[byte_index] with bit mask
if (bit)
rom_id->byte[byte_index] |= bit_mask;
else
rom_id->byte[byte_index] &= ~bit_mask;
// ROM search write
//cli();
dallasWriteBit(bit);
//sei();
// ncrement bit index counter and shift the bit mask
bit_index++;
bit_mask <<= 1;
if (!bit_mask)
{
// if the mask is 0 then go to new ROM
// accumulate the CRC and incriment the byte index and bit mask
dallasCRC(rom_id->byte[byte_index]);
byte_index++;
bit_mask++;
}
}
