Device error state

[pelikhan]

Is there a register to surface an error state in device?

[pelikhan]

Is there a register for the error state of a device?

[mmoskal]

@jamesadevine should we have a string register in control service? or maybe a common string register for every service? or should that be numeric?

@pelikhan do you have specific use cases in mind?

I was thinking hardware errors like:

• my I2C accelerometer doesn't work (we currently panic, which may be actually better)

[pelikhan]

I was thinking about surfacing the panic error code.

[jamesadevine]

I was thinking a register in the control service that exposes a "list" of errors if there are any.

In the case where hardware isn't working, I think it is better to panic and send a message over JACDAC.

[pelikhan]

should a device has a "safe boot" option that ignores all sensors and just broadcasts the error code?

[mmoskal]

It could just broadcast while the sensors are broken, I don't think there's much need to safe boot.

[pelikhan]

does jacdac still broadcast while in panic mode?

[pelikhan]

I understand we want to avoid a broken device polluting the bus with error messages.

[jamesadevine]

Yeah, I think you'd just continue sending advertisement reports with some error flag set. A JD debugger/brain could then interrogate a device for its error state when connected

[tballmsft]

• bit in the advertisement packet for failure
• bundle a report packet in the case of a failure
  • generic code
  • device specific

Kinds of Failures:

• hard fault (segmentation violation) vs. software panic (OOM, etc.)
• hardware failures (I2C device doesn't respond)

Common failure codes for JACDAC:

• generic codes (SUCCESS, ...)
• device-specific codes

Take a look at: https://en.wikipedia.org/wiki/CAN_bus

[pelikhan]

Base register in the service definition

[pelikhan]

https://github.com/microsoft/jacdac/pull/91