Thank you @cleve
It works with

unipi@L203-sn121:~$ sudo /opt/unipi/tools/fwspi -u 1 -P -U
unipi@L203-sn121:~$ sudo /opt/unipi/tools/fwspi -u 2 -P -U
unipi@L203-sn121:~$ sudo /opt/unipi/tools/fwspi -u 3 -P -U

@cleve Thank you very much, but I don't understand what I should do next...
here's what I did:

unipi@L203-sn121:~$ sudo /opt/unipi/tools/fwspi -u 1
Boardset:     0 B-1000                         (v1.0)
Baseboard:    0 B-1000                         (v1.0)
Firmware: v5.3 (for 0-1)
PLEASE UPGRADE FIRMWARE TO 6.30 - to proceed, execute fwspi -P -U

And that :

unipi@L203-sn121:~$ sudo /opt/unipi/tools/fwspi -u 1 -P
Boardset:     0 B-1000                         (v1.0)
Baseboard:    0 B-1000                         (v1.0)
Firmware: v5.3 (for 0-1)
PLEASE UPGRADE FIRMWARE TO 6.30 - to proceed, execute fwspi -P -U
Cannot open file /opt/unipi/firmware/B-1000-1.bin

Hello,
When I run the command /opt/unipi/tools/fwspi -i 0 I get this error
ARMINIT: Cannot open device /dev/unipispi
Unable to create the arm[0] context
What can I do? Thanks

that's my disto:
Linux L203-sn121 6.6.31-v8 #1 SMP PREEMPT Fri Jun 28 10:02:55 UTC 2024 aarch64

@cleve Yes, of course, there's a writing error in your example. To read the value of a digital output, you should write DO1.1 instead of DO1.01 (without the 0). It's the same for a digital input, you indicate DI1.01 when you should write DI1.1 (without the 0).

Hello,
In this example : cat /run/unipi-plc/by-sys/DO1.01/value
that you give on this page : https://kb.unipi.technology/en:sw:02-apis:04-sysfs
there is an error because I need to use this command to get a convincing result : cat /run/unipi-plc/by-sys/DI1.1/value
I think you need to review this document, don't you?

Hello,
I have just installed Base OS x64.
The ssh access via eth0 works but I can't configure wlan0.
I see that the configuration file /etc/wpa_supplicant/wpa_supplicant.conf usually found on Raspbian does not exist on Base OS.
I've tried editing /etc/wpa_supplicant/wpa_supplicant-wlan0.conf but it still doesn't work.

Do you have a solution for me?