OneWire DS18B20 on mighty 1284p can't find my sensors, same work w/ Duemilanove

Other Hardware 3rd Party Boards
1

Hello,

I have uploaded the DS18x20 Temperature example sketch to my proven Duemilanove and my mighty 1284p.

On the Duemilanove my two DS18B20 temperature sensors are found and read correctly:

ROM = 28 36 6D 51 4 0 0 75
  Chip = DS18B20
  Data = 1 D6 1 4B 46 7F FF A 10 43  CRC=43
  Temperature = 29.37 Celsius, 84.87 Fahrenheit
ROM = 28 19 6 51 4 0 0 86
  Chip = DS18B20
  Data = 1 A7 1 4B 46 7F FF 9 10 E0  CRC=E0
  Temperature = 26.44 Celsius, 79.59 Fahrenheit
No more addresses.
(...)

Whereas the 1284p only says

No more addresses.

No more addresses.

(...)

I have not changed the wiring of the sensors; they are connected +5/GND, Data is pulled to +5V with a 2k7 and also to the reading pin, respectively. I have tested multiple Pins - they all work on the Duemilanove, none work on the 1284p.

I am assuming some issues with I2C with mighty 1284p, but maybe someone else has another idea.

Thank you, as always;
Christian.

2

Turns out I had the ATMega1284p running at "just" 1 MHz. Fusing it to run at 8 MHz made everything work just fine. Stable connection, reliable recognition of sensors, no data dropouts as far as I can see.

I'll try to get in contact with the mighty1284p and Arduino OneWire Library folks to discuss this, I guess their code either hardcodedly assumes the device to be running at 8 MHz or having it run at 1 MHz makes the communication unreliable.