@il77781 All valid questions from customer perspective. However, Argon did not publish any essential pin documentation and does not reply to any technical questions after sending multiple reminders.
The firmware revisions of the Argon One case changed in time silently and behavior changed as well. I could not find a way to retrieve the exact firmware version. For this reason difficult to tell which one you have and some experiments are needed.
- Do I understand correctly that in this case I can connect to GPIO other devices that use pin 8 (TXD), and the Argon One operation will not interfere with the operation of these other devices?
An experiment is required if the I2C shutdown command 0xff works when using this GPIO pin.
- Do I understand correctly that 0xfd and 0xfe are set using a jumper on the Argon One board?
No. I2C shutdown commands are write only and availability of these commands depends on the programmed firmware of the Argon One microcontroller. AFAIK, some cases can be programmed with the 0xfd and 0xfe I2C commands, others are using a jumper. In my case a jumper configures 2 modes and has no effect on 0xfd and 0xfe commands:
- Jumper mode 1: Turn the Raspberry Pi immediately on after connecting power to the case, or:
- Jumper mode 2: Do not turn Raspberry Pi power on when connecting power to the case, the power button should be used instead and is controlled by the microcontroller.
- From “whom” Argon One receives 0xff?
Argon created an installation script for Raspbian OS only. This script installs a service, checks the GPIO power button state and sends a shutdown command 0xff. 0xfd and 0xfe are not used. Fan speed control does not work with my version and Ubuntu 20.04 64-bit did not work as well. There are many forks of this script on Github, again zero support from Argon.