SPI clock stops clocking low pulses when peripheral is powered on (time-to-digital AS6500 chip)

[espruino-discuss2]

Posted at 2021-08-27 by user133661

Hi,

I am trying to get SPI communication to work between my Espruino Wifi and a time-to-digital dev kit.

If the dev kit board is powered off, the SPI signals from Espruino looks good (I am using a logic interface to debug). But as soon as the dev kit board is powered on, the SCK clock signal stops pulling low, -it is always high with some sporadic short low pulses.

I am a programmer with very little experience from the world of electronics. Does anyone have an idea what could be wrong?

Kind regards,
Johan

[gfwilliams]

Posted at 2021-08-27 by @gfwilliams

Have you connected the GND wires together on all the boards? That's usually the #1 issue for things like this that change when you apply external power

[espruino-discuss2]

Posted at 2021-08-27 by user133661

Yes, I have connected all GND wires together.

I have tried powering both devices from USB (USB -> Espruino Wifi -> external board connected to GND and 3.3V pins of the Espruino Wifi)

and also tried powering both boards from an external 3V power supply (not 3.3V, only 3V...) using the GND and 3.3V. pins of the Espruino Wifi with USB disconnected.

The output in the logic analyser looks the same - when the external board powers up, SCK stops pulling low.

[espruino-discuss2]

Posted at 2021-08-27 by user133661

I found the error, one of the pins of the dev kit board is actually mislabeled in the data sheet. I have reported this to the manufacturer now.