Relay board with hardware watchdog for Particle devices

Hardware
1

Hi guys,

are there any relay boards for Particle with a hardware watchdog on board available today?
Thanks!
Gustavo.

2

Hey @gusgonnet good to hear from you again man.

Not exactly sure what you’re asking here. Can you explain? All the watchdogs I’ve ever implemented in the past were software based.

3

Hey Travis! Nice chatting with you.

Apologies for not being clear. I need a board with relays for Particle devices. The project will be safer if the board has a hardware watchdog in it. I updated the topic title to reflect this.

At some point in time in the past there was a request from a person to add a watchdog into a Particle board, the topic is here.

I wanted to know if that work materialized in some way.

Or, I want to use a relay board like this one, but the application requires a hardware watchdog (to be on the safe side if the MCU hangs)
Anything that you guys may have in store can fit this project?
This kind of board but with a hardware watchdog, or a hardware watchdog addon somehow can help.:


image

Thank you!
Gustavo.

4

Hi Gustavo,

All of our relay boards compatible with Particle are going to be using the MCP23008(boards with 8 relays or less) or an MCP23017(boards with more than 8 relays). These MCP230 chips are basically I2C connected GPIO multiplexers. To my knowledge they don’t have any sort of built in watchdog which could switch the relays off if the MCU were to hang. Something like that would require some sort of secondary processor.

Have you ever worked with the ESP32? It has 2 processor cores. In this way the second core could be used as a watchdog so if the primary core were to go down for any reason or lock up the second core could turn the relays off or set them to a safe state. That would be about the best recommendation I could make for what you’re describing.

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5

Hi @gusgonnet,

I use an external Timer as a watchdog, with the NCD boards on several critical projects.
image

The Count-down timer gets reset with a Digital Pin after each successful “WDT” webhook response.

I use the “WDT” publish/subscribe on a 30 minute schedule (adjustable) as a failsafe. If the timer runs out (the webhook response didn’t make it back to the Electron/Boron), then the NCD Board & Particle’s power will be switched off and will remain in the un-powered state for a user defined length of time (I use 15 seconds). After that, power is restored to the NCD Board and the next timer cycle begins.

This is not a neat or as clean as a “real” watchdog IC solution. But the easily adjustable ON/OFF Countdown Timer values and the visual feedback are nice, and it’s only 1-wire plus power.
It can be used as a typical hardware watchdog too, but I like only petting after a successful publish (to catch Connectivity issues).

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6

@TravisE_NCD_Technica @rfontaine
thank you very much guys for the suggestions and ideas.
I will have all this in mind - thanks a bunch!
Gustavo.

1 Like