I've have a temperature monitoring system using Maxim DS18B20 temperature s ensors. To verify correct temperature, I compare the sensor crc (Byte8) in the sctatchpad with the calculated crc. Ninety nine percent of the time, th e CRCs match and everything is fine, but occasionally, I get a CRC mismatch . After verifying against an online CRC checker I see that the sensor crc i s incorrect. I normally try a number of resamples to try and correct the is sue, but I see that in some cases after 10 resamples the sensor crc is stil l incorrect.
I've checked the pcb and it is fine. I'm using a 4.7K pullup. I don't use p arasitic power supply and the configuration register is set for 9 bit resol ution. I also allow one second for conversion. Anybody got any idea what could be wrong or run into this issue themselves? Any help greatly appreciated.
Many Thanks Bob Carter