Unstable SPI communication

I am using Matrix Creator directly with HAL by executing the matrix-creator-hal demos.
Running everloop_demo, the result is not as expected. There seems to be a mismatch probably caused by wrong timing of the bus:

  • The first LED is working right.
  • The next LEDs more and more start to flicker and show wrong values.
  • The last 8 LEDs do not work at all.

I tried reboots of the whole system, but this does not help.
When cooling down the board it looks more stable for the first LEDs but still does not work properly.
The flickering of the LEDs continues even when stopping the everloop_demo and it changes with CPU load.

I think this a HW problem (timing or signal quality), but before changing the board I would like to know if it may be a RPI isssue.

3 hours later…:
I have now tried another RPI and whow: matrix creator is running well. So it seems to be an issue of the RPI or the interface between RPI and matrix creator.

Is there possibility I can do some check or fix e.g. some SPI configuration (speed, impedance, pull-ups)?

I am using a RPI2 and tried with 2 different original RPI power supplies (2.5A).

We have only seen similar behaviors with power supplies with voltage higher than 5.2V. For troubleshooting you can use other power supplies, e.g. a smartphone charger or use a laptop USB.

Let us know how it goes.

Yoel