T9-Usage-display

The code for using a T-Mobile T9 (Franklin Wireless R717) As a display with a Raspberry pi 4

Usage

1. Enable adb through ssh
2. Compile code
3. Connect to device with usb cable
4. Profit

Getting Access to the hotspot

https://snt.sh/2020/09/rooting-the-t-mobile-t9-franklin-wireless-r717/

Enable SSH

curl "http://192.168.0.1/cgi-bin/webpst.service_setting.cgi" \
 -H "Content-Type: application/json" \
 -H "Origin: http://192.168.0.1" \
 -H "Referer: http://192.168.0.1/webpst/usb_mode.html" \
 --data '{"command":"save","params":null,"data":{"ssh":"on","tether":"","bridge":""}}' \
 --insecure

Enable ADB

Edit the /data/configs/mobileap_cfg.xml file. Update the UsbMode setting value from 9025 to 902D, save, then reboot the device. Note you also may need to replace the contents data/configs/hsusb_next with 902D as well.

Commands piped through adb shell

Display Text

/usr/bin/guimgr_cli lcd_eng_mode xMessageHere

reset

/usr/bin/guimgr_cli lcd_eng_mode 0

Blank the LCD

echo 1 > /sys/class/graphics/fb0/blank

TV static

cat /dev/urandom > /dev/fb0

Other Notes

It seems overall they use nano-x as the GUI manager. If you want to bit bang > raw data to the LCD, /dev/fb0 is your man. You can kill the process that draws to the buffer (nano-X) and it won’t clear it on you anymore, but you’ll lose the backlight control. It’s 128x36px, 1 bit per pixel.

You can control the backlight yourself, but you’ll need a helper program for it. Cross complies on ubuntu with arm-linux-gnueabi-gcc just fine

On: ioctl(28, _IOC(0, 0x00, 0xc8, 0x00), 0)
Off: ioctl(21, _IOC(0, 0x00, 0xc9, 0x00), 0)

   Where 28/21 is just an fd to /dev/fb0

#include
#include
int main() {
return ioctl(open(“/dev/fb0”, O_RDWR), _IOC(0, 0x00, 0xc8, 0x00));
}