Hey all,
I am working on a boron remote sensor and have been experimenting around with a TPL5010 watchdog timer for my Boron404X following closely to the ParticleDocs TPL5010 example. I currently have it set up with 53.5k resistor (107k's in parallel) for an approx. 8min reset timer, and using the unedited code in the example above with a 2min cycle. On powerup, the Boron immediately is reset, with either a solid white light or no light out of the status LED, indicating to me that the reset line is being constantly activated. My multimeter is reading 1.6V on this line relative to ground when this is occuring. Im honestly not sure what the next steps are for diagnosing & resolving this issue, so im looking for anything that can help. Ive inspected all of the solder joints and all have been behaving as expected as far as I can tell. Here is my setup:
I have done a bit more digging. When the LED is in solid white, I am able to manually set the DONE line in the 5010 high through a jumper wire. Doing this follows the intended behaviour of the watchdog, until the next cycle when RESET is set low, which returns it to the solid white LED state. I am unsure if this indicated a software issue on the Boron not resetting properly, or an issue with the watchdog not returning to the normal state after pulsing the RESET line. Let me know if there is any information you need me to provide to help diagnose this further.
In the Particle TPL5010 example, the DONE line has a pull down, not a pull up. It looks like you have a pull-up in your circuit. Now that I look at it again, I guess it is pull-down.
Is the white wire really plugged into D6, which should be 24? It looks like it might be plugged into D7 but it's hard to tell. D7 has a LED on it, which can cause pull to behave unexpectedly.
Also on the Boron with Device OS 5.3.0 and later the hardware watchdog in the MCU is quite good and is sufficient for most cases where you're using a TPL5010.
https://docs.particle.io/reference/device-os/api/watchdog-hardware/
I am doing this as a project specifically for external watchdogs at the moment.
The issue seems to be with the inital startup of the TPL5010 never setting the RSTn line high. As its stuck in low, its continually resetting the board. Still diagnosing it, but nothing coming up conclusive.
As Rick stated - the external Watchdog is the preferences - I've had to debug countless issues with external watchdogs firing when they should not. (During OTAs, sleep etc.)
If at all possible the internal HW Watchdog should get you where you need to be.