So I am trying to run UART4 TXD to a Parallax 4x20 LCD serial screen. I have tried at three different baud rates (2400,9600,19200) and I can’t get serial commands sent to it via UART4 TXD (P9 - pin 13).
Here is my output from the muxing:
root@omap:# echo 6 > /sys/kernel/debug/omap_mux/gpmc_wpn
root@omap:# cat /sys/kernel/debug/omap_mux/gpmc_wpn
name: gpmc_wpn.(null) (0x44e10874/0x874 = 0x0006), b NA, t NA
mode: OMAP_PIN_OUTPUT | OMAP_MUX_MODE6
signals: gpmc_wpn | mii2_rxerr | NA | rmii2_rxerr | mmc2_sdcd | NA | NA | gpio0_31
The screen is run at 5v, and it’s a measured 3.3v coming out of the Beagle Bone to the screen.
I have tested all three baud rates by breadboarding an Arduino with a 3.3v regulator (to mimic the Beagle Bone) from TXD, and the screen works perfectly fine. From a hardware perspective I think I am good, however, I can’t fathom why I can’t send any commands to the screen from the Beagle.
Thanks in advance.