Forum 2005-2010 (read only)
1-Wire, DS18B20... How do I search the bus?
Topic: 1-Wire, DS18B20... How do I search the bus?
(Read 22 times)
Jobless Computer Engineer
Re: 1-Wire, DS18B20... How do I search the bus?
Jun 21, 2010, 06:35 am
I used 4.7k standard pull-up for 1Wire device bus. I don't tested under chilled temperatures. But
gives correct reads >127 C degrees with DS18B20's without single bit of error with both powered & parasite power connections... I don't wait different results under -55 C degrees. It might change it's characteristic on different batches +- 1 or 2 uS. But there is ~10uS margin surely will protects us. So +1uS will not arise trouble.
At my situation, I think it's required to use higher value of resistor since I wanted to longer "0" pulses, not shorter one, that slow downs line pull-up. I can turn around this problem on my local setup via using altered OneWire library code or electronically by using new resister. But I just wanted to make Arduino's OneWire library more compatible with OneWire spec. At least, please think about adjusting reading time to 14uS that matches with DS18B20 master sample time.