CMM2: DS18B20 Temp sensor problem

Author	Message
TassyJim Guru Joined: 07/08/2011 Location: Australia Posts: 6455	Posted: 09:49pm 09 Aug 2020         robert.rozee said     TassyJim said   According to https://github.com/cpetrich/counterfeit_DS18B20 Your rom code is wrong due to the "20 02" last two numbers which should be zeros. Rob, you left out the bit about conversion times   Quote   Based on the timing for 12 bit conversion, your device is group A2. While I agree that the rom code 'could' be valid, it is unlikely in the extreme that Maxim will have produced a batch of chips that do the conversions in half the time, and then gone back to the normal time in subsequent batches. I suspect that the clone manufacturers chose rom codes well outside the expected range to prevent the chance of duplicate codes being discovered in the immediate future. The chips that Mick and I purchased from the Jaycar supply chain, all have slower timing than the usual times seen with known good chips, but the timing is still within published specs so 'could' be valid, but suspicious. I buy through Ebay. I expect clones, recycled chips, out-of-spec rejects... Jim