I am using a PiTFT 2.8" on an original Raspberry Pi B. I just reinstalled Raspbian and setup the PiTFT using the Adafruit easy install script to launch to console.
I have a python script that communicates using serial via USB on /dev/ttyUSB0. My script only runs correctly and accesses the USB port when an HDMI cable is plugged in. (If I unplug the HDMI, it won't communicate over serial; if I plug it in, it does.) I assume this has to do with a setting in /boot/config.txt, but I can't figure out which.
Here is config.txt:
# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See link above for details
# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1
# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
disable_overscan=0
# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16
# uncomment to force a console size. By default it will be display's size minus
# overscan.
#framebuffer_width=1280
#framebuffer_height=720
# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=0
# uncomment to force a specific HDMI mode (this will force VGA)
# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2
# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
#config_hdmi_boost=4
# uncomment for composite PAL
#sdtv_mode=2
#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800
# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on
# Uncomment this to enable the lirc-rpi module
#dtoverlay=lirc-rpi
# Additional overlays and parameters are documented /boot/overlays/README
# Enable audio (loads snd_bcm2835)
dtparam=audio=on
# --- added by adafruit-pitft-helper Wed May 15 16:54:04 CDT 2019 ---
dtparam=spi=on
dtparam=i2c1=on
dtparam=i2c_arm=on
dtoverlay=pitft28-resistive,rotate=270,speed=64000000,fps=30
Any help is much appreciated.
