On a Raspberry Pi I have a program that was working great using the serial port /dev/ttyAMA0. Now all of a sudden it doesn't work. When I try and open the port, it only opens sometimes and when it doesn't, it hangs forever. When I look at the port data with a logic analyzer, I get "ERROR" bytes coming from it. I tried running "screen /dev/ttyAMA0 115200" and I get "ERROR login incorrect ERROR" messages. It's as if some program has control over the port. If I did something, I don't know what it was. How can I find out what might be using the port besides me?
I decided to put an FTDI cable on the serial port and see what happens on a bootup. Here is what I got:
[ 380.473251] reboot: Restarting system
ERROR
Uncompressing Linux... done, booting the kernel.
ERROR
ø
ERROR
Welcome to the rescue system
ERROR
recovery login:
ERROR
Welcome to the rescue system
ERROR
recovery login:
ERROR
Welcome to the rescue system
ERROR
recovery login:
ERROR
Welcome to the rescue system
ERROR
recovery login:
How do I prevent the system from using the tty/AMA0 port? I'm using it to connect to a Wifi module.
Terry
