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  • I am using several (~35) puck lites to collect temperature data via external thermistors wired to pins 28, 30, and 31 following a similar procedure to your thermistor write up. I'm also advertising the data for live view capability. The thermistors are monitoring human skin temperature. Mostly they work fine and seem to be quite accurate.

    The problem is, every day I use them I am losing about 2-3 pucks. They start reading bad temperatures, usually 5-10 deg. F higher than they should be, but sometimes 60 or more degrees off (which is a lot easier to spot!). When I disconnect the thermistor and check with a multimeter they frequently have low to very low impedance between pins 30 and 31 (the middle of the voltage divider and the low signal), but not always. I have not been successful in getting them to work again, at least without changing the circuit layout, and end up changing out the boards completely.

    Another problem I see less frequently is the puck will completely crash for no apparent reason (it's more than a software reset - it loses its NRF advertising settings too). It's as if the battery died but it happens on fresh batteries and only an hour or so into logging/advertising. Often this will result in the bad measurements as above when I try to refresh them.

    My best guess is static discharge is frying my boards but I'm really at a loss. Should I be using a capacitor to protect the ADC pin?

    I'm using SR type probes from here:­ection/Thermistor_Probes.htm

    Thanks for any insight!


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