TTYO0 mystery

Hi board,

I’m working on a project and there are some comms traditionally done by RS232. The “cape” already has a FTDI chip connected to J1 for convenience. So I thought that might just be the easiest solution, tell C to latch onto ttyO0 and call it a day. Well it worked alright but the open terminal on that port kinda got in the way. So I went into uEnv.txt and moved the terminal (the splurge of info on boot isn’t a big deal). However now TTYO0 is basically unresponsive. When I open TTYUSB1 on my PC with screen the boot splurge happens and then after the kernel is booted there is no more output and it won’t accept input. When I run my application screen stays unresponsive.

Finally I wanted to see if I could finagle it working even with the terminal running on TTYO0 (login and run a program that doesn’t poll the resource). However, after changing uenv.txt back the terminal hasn’t come back after several reboots. I might have changed other stuff in trying to get it to work but I can’t remember what. What else controls the function of TTYO0?

Also if I sudo echo to ttyO0 it doesn’t show on the terminal monitoring it on the other side.

Does the file /etc/inittab

Contain a line similar to this → T0:23:respawn:/sbin/getty -L ttyO0 115200 vt102

??

Finally I wanted to see if I could finagle it working even with the terminal running on TTYO0 (login and run a program that doesn’t poll the resource). However, after changing uenv.txt back the terminal hasn’t come back after several reboots. I might have changed other stuff in trying to get it to work but I can’t remember what. What else controls the function of TTYO0?

Double check to make sure the changes stuck. Also what is the pout put of :

$ cat /proc/cmdline

?

/etc/initab does have that line

the output of cat /proc/cmdline is
console=tty0 console=/dev/ttyO0,115200n8 capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN,BB-BONE-EMMC-2G root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait fixrtc quiet init=/lib/systemd/systemd

I got the program working I think by sudo killall screen although I don’t remember starting a screen since reboot so I’m not 100% that was the fix. I still don’t get a terminal on ttyO0 anyway.

remove “console=tty0” and see what that results in.