I'm attempting to have a cm4 talk to an MCU over UART. In the process of having the MCU send a message to the CM4 over the io board j8 pins 8 and 10 (maps to GPIO14 and 15) I noticed that the rpi could receive serial just fine, but could not send it back. Instead, what was sent never made it to the MCU, and would receive what it sent. I concluded that there is an echo on /dev/ttyAMA0.
I was able to repro the echo on a cm5 and cm5 IO board, but was not able to repro on a pi 4 Model B.
As a side note, I found that on the cm5 it would echo back at a baud rate of 9600, and on the cm4 it would echo back at 7200.
I disabled the serial console, I disabled bluetooth, I disabled getty, and as far as I can see, I have followed just about every tutorial out there for enabling UART. Does anyone know where this echo could be coming from?
I have latest lite versions of bookworm running on each device. Thanks to anyone who can help me on this![:)]( "Smile")
I was able to repro the echo on a cm5 and cm5 IO board, but was not able to repro on a pi 4 Model B.
As a side note, I found that on the cm5 it would echo back at a baud rate of 9600, and on the cm4 it would echo back at 7200.
I disabled the serial console, I disabled bluetooth, I disabled getty, and as far as I can see, I have followed just about every tutorial out there for enabling UART. Does anyone know where this echo could be coming from?
I have latest lite versions of bookworm running on each device. Thanks to anyone who can help me on this
Statistics: Posted by matthewassoc — Tue Jan 14, 2025 8:11 pm — Replies 0 — Views 13