18F4420 and 1-Wire

[Amoque]

Yes, of course.

I forgot the pull-up resistor (4K7) when designing the board. I had intended to add it at the "plug" end of the cable, then forgot that as well; without this pull-up the "Waitloop" never exits. Once the hardware was correct, the temperature readings were suspiciously low (I suspect for the reasons Alain suggests). "Room temperature" reading was 62F, but my analog thermometer read closer to 70F; placing the sensor under my arm should have demonstrated somewhere near 98F, but the measured value was only 85F. Bruce's (Reynold's Electronics) conversion routine gives more accurate results:

Dummy = Raw_Temperature * 1125
Raw_Temperature = DIV32 100
Raw_Temperature = Raw_Temperature +3200
Temp_in_F = Raw_Temperature

While I cannot verify that this formula yields precise results, room temperature reading of 69.14 was much closer to thermometer reading 0f 70; and under arm reading rose to 97+.