hardware-interfaces/spi/

[giscus[bot]]

hardware-interfaces/spi/

Introduction

https://documentation.onioniot.com/hardware-interfaces/spi/

[denfaj]

Hi,
I am having problem on version OpenWRT:
root@Omega-E58B:~# cat /etc/os-release
NAME="OpenWrt"
VERSION="23.05.3"
ID="openwrt"
ID_LIKE="lede openwrt"
PRETTY_NAME="OpenWrt 23.05.3"
VERSION_ID="23.05.3"
HOME_URL="https://openwrt.org/"
BUG_URL="https://bugs.openwrt.org/"
SUPPORT_URL="https://forum.openwrt.org/"
BUILD_ID="r23809-234f1a2efa"
OPENWRT_BOARD="ramips/mt76x8"
OPENWRT_ARCH="mipsel_24kc"
OPENWRT_TAINTS=""
OPENWRT_DEVICE_MANUFACTURER="OpenWrt"
OPENWRT_DEVICE_MANUFACTURER_URL="https://openwrt.org/"
OPENWRT_DEVICE_PRODUCT="Generic"
OPENWRT_DEVICE_REVISION="v0"
OPENWRT_RELEASE="OpenWrt 23.05.3 r238"

I am using python and spidev according to this manual.

My hardware requires SPI mode 3 (CPOL = 1, CPHA = 1) but when I set to spi.mode = 3 and I send bytes using xfer3 like spi.xfer3([0xFF,0xFF,0xFF,0xFF,0xFF,0xFF],0)

I get the following error:
OSError: [Errno 22] Invalid argument

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
File "/root/spi3.py", line 78, in
spi.xfer3([0xFF,0xFF,0xFF,0xFF,0xFF,0xFF],0)
SystemError: <method 'xfer3' of 'SpiDev' objects> returned a result with an exception set

When I look into the log:
root@Omega-E58B:~# dmesg | grep spi
[ 0.375176] spi-mt7621 10000b00.spi: sys_freq: 193333333
[ 0.411913] spi-nor spi0.0: mx25l25635e (32768 Kbytes)
[ 0.417374] 4 fixed-partitions partitions found on MTD device spi0.0
[ 0.423870] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
[ 0.431376] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
[ 0.439388] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
[ 0.446871] OF: Bad cell count for /palmbus@10000000/spi@b00/flash@0/partitions
[ 0.454607] Creating 4 MTD partitions on "spi0.0":
[ 884.823823] spidev spi0.1: setup: unsupported mode bits 3
[ 2315.442212] spidev spi0.1: setup: unsupported mode bits 3
[ 2404.149346] spidev spi0.1: setup: unsupported mode bits 3
[ 2423.349365] spidev spi0.1: setup: unsupported mode bits 3
[ 2453.193319] spidev spi0.1: setup: unsupported mode bits 3
[ 2461.649283] spidev spi0.1: setup: unsupported mode bits 3

I see that spi mode 3 is not supported.

If I set mode to 0 then for instance a simple read operation works only for the first time
response = spi.xfer3([0x50],3)
config_value = (response[0] << 16) | (response[1] << 8) | response[2]
print(f"{config_value:024b}")
First time I get correct response
000000000000000100010111
and second time I get only 0.
000000000000000000000000

Please explain me how to enable mode 3 or how to use Onion with device that requires SPI mode 3.

[greenbreakfast]

Hi @denfaj, we're happy to help look into this technical question, but we intend the documentation comments to be suggestions or questions about the content of the articles.
For technical questions, please create an Issue in the OnionIoT/OpenWRT-Packages repo or make a thread on the Onion Community Forum