try to slow down interface timing, if you have more than half a meter of cabling. i use about 20 ds1621 on a f84 with up to 20m of cabling and run the whole thing at a clock frequency of 1kHz. also try to use serial resistors (a few 100 ohms) on the bus to reduce switching current. tino Steven Allard Gesendet von: pic microcontroller discussion list 15.12.01 12:50 Bitte antworten an pic microcontroller discussion list An: PICLIST@MITVMA.MIT.EDU Kopie: Thema: [PIC]: DS1820, 16F873 and CC5X Hello all, I've written some routines to talk to a DS1820 thermometer. The program works 95% of the time, the other 5% it returns 0xFF for all the scratchpad locations. ie the 1820 is not responding, although the presence pulse after the master bus reset is OK. As far as I can tell the routines are correct I've checked the timing etc. I've also tried not using the ICD, and disabling interrupts, while reading/writing. Can anyone tell me whether its a problem using portA. I'm using a 4K7 pull up resistor and the port is configured for digital (ADCON1=0000.0110). Best Wishes Steve Allard -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu