Hello. FYI, I’ve released a new ER-301 firmware (v0.3.19) that silences all of the UART/I2C chatter that I possibly can. Unfortunately there is still a tiny bit of chatter remaining, right at the beginning of the boot up which I can do nothing about because it is burnt into the ROM factory boot code of the AM3352 CPU in the ER-301.
When powered on, the AM3352 starts executing boot code from ROM that brings up the SD card and searches it for a bootloader. During this process it sends the following message to the shared UART/I2C port:
Detected SD Card version : 2, High Capacity
bus width: 4-bit
bus freq: 25MHz
Other than that there is no activity on the lines. My preliminary tests show that the Teletype does not freeze during the ER-301 startup but I would like some confirmation please.