balenaOS ignores dtoverlay?

Product support balenaEngine
1

Hi,

I’m trying to change the chip select pins for SPI0 by applying a device tree overlay. However it looks like the configuration is not getting applied correctly. or being ignored. I’m using:

Device: Raspberry Pi 4 (using 64bit OS)
Host OS: balenaOS 2.85.2+rev3 (development)
Supervisor: 12.10.10
Local mode

Here are the steps I’ve taken:

  1. I flashed a new image, modified the config.txt, and then booted the device for the first time. When I ran cat /mnt/boot/config.txt, my changes could not be seen not. It looks like the default configuration from the fleet/application was used instead.

  2. Then I updated the device configuration using the dashboard. These changes do appear in /mnt/boot/config.txt after a reboot.

    Device configuration

    RESIN_HOST_CONFIG_dtparam="spi=on"
RESIN_HOST_CONFIG_dtoverlay="spi0-2cs,cs0_pin=04,cs1_pin=27"

    /mnt/boot/config.txt

    disable_splash=0
dtoverlay=spi0-2cs,cs0_pin=04,cs1_pin=27
dtparam=spi=on
enable_uart=1
gpu_mem=396
arm_64bit=1
avoid_warnings=1

  3. In an application container, I used Python and pigpio to send some data on the main SPI bus, channel 0, SPI mode 3.

    import pigpio
pi = pigpio.pi()

h = pi.spi_open(0, 50000, 3)
pi.spi_write(h, b'\x21\x00\x00\x00\x00')

    On a scope, it can be seen that the RPI is still using the default chip select pin (GPIO 8) and not the pin configured in the config.txt file (GPIO 4).

    scope1
    scope1800×480 10.5 KB

Do you know why this could be happening? Is there another way to test/print how SPI0 is configured on the RPI4?

Thanks!

2

Nevermind!

The issue is not with balenaOS. It was caused by the pigpio library – the SPI chip select lines have been hardcoded. Sorry about that!

I’ve opened an issue there regarding this.

2 Likes
3

Hey there and thanks for reporting back @gautam_io :slight_smile:
I would have been surprised, but good to know that it is not an issue with balenaOS.
The only real problems I witnessed in regards to Overlays, was that sometimes people try to load some which are not yet available in the boot/overlays folder - coming from Raspberry Pi OS and thinking that should work… But to be honest, that also has been way back :slight_smile:

Thanks again and I hope you get your project done in no time :slight_smile: !

1 Like
4

Thank you @gautam_io and welcome to the community. Let us know once the pigpio library solves this problem that everything is working fine :slight_smile:

Thank you @nmaas87 for your amazing support! you rock!

1 Like