Resourceful Pocketeers on the forums have banded together to figure out how to swap out the stock LCD screen on PocketC.H.I.P. for an even bigger, 5″ LCD capable of rendering at 800×480 pixels.
MarekLew was the first to connect the bigger screen to PocketC.H.I.P. and share the news in the forum. Kilrah completed the hack soon after and shared some great photos of the screen swap process. And cmspooner’s post explained how to calibrate the touchscreen using a config file.
This post synthesizes the information from the three threads into one easy-to-deploy configuration file. Plus, having everything in a config file means that even if you reboot PocketC.H.I.P., the settings with remain in effect.
- Paperclip (or jumper wire)
- Needle-nose pliers
- Putty knife
- Wireless USB keyboard & mouse combo
There’s no sense in rushing through this project. LCD panels are fragile and can be easily broken. Take your time. Have fun. Hack at your own risk. And ask any questions you have in the forums or comments below.
Turn off PocketC.H.I.P. and remove the plastic around the perimeter of the screen. Flip PocketC.H.I.P. over, remove C.H.I.P., as well as the back of the PocketC.H.I.P. case.
Note: Currently this hack only works with the C.H.I.P. software image.
Use needle-nose pliers and disconnect the battery. Make sure to only pull on the plastic JST-connector, not on the wires.
With the wires disconnected, carefully pull the battery away from the adhesive tape connecting it to PocketC.H.I.P.. Don’t try to pull off the battery in one big tug. Be patient and slowly work each side of the battery free from the tape.
With the battery out of the way, you can now access the LCD flexible printed circuit (FPC) connector. Gently pull the dark plastic portion of the connector toward the cable.
When the connector is loosened, simply pull the cable out of the connector. Avoid sticking the FPC cable to the exposed sticky foam, it can be a pain to separate.
It is fairly easy to crack the LCD and cut the FPC cable during removal. Be patient and take your time. Use a putty knife to slowly work your way around the perimeter of the LCD, cutting and gentle prying the adhesive foam between PocketC.H.I.P. and the LCD.
Once the adhesive foam no longer has its hold on the LCD, remove the screen and FPC cable from PocketC.H.I.P. and set aside.
Place the new LCD viewing-side down on a non-marking surface. Carefully bend the LCD FPC cable and slide it through the slot in the middle of PocketC.H.I.P..
Make sure that the FPC connector is in the open position and slide the FPC cable into it. (This is shown in the image above.) When you feel resistance from the connector, push the two parts of the connector together to secure the connection.
Use Kapton tape to cover any exposed solder pads that might contact the new, larger LCD. The tape is visible in the image above in maize. Shorting shouldn’t be a problem, but it’s a good habit to proactively use the tape.
Cut at least four strips of foam tape and adhere them to PocketC.H.I.P.. Use the pink rectangular outline on the silkscreen as a placement guide. The key is to apply enough tape that it supports the display when you press it. If you don’t, the LCD will bend and you’ll see a distorted display.
Take your time with this step. Use the tab slots above PocketC.H.I.P.’s keyboard to help you align the screen. Make sure you don’t cover up the exposed solder pads for the GPIO at the top of PocketC.H.I.P.. The screen will overhang the PocketC.H.I.P. on either side of the PCB.
Once you place the screen down on the foam tape, there’s very little wiggle room to change the orientation. Use a steady hand.
Place the battery back on the foam tape you removed it from in Step 3. Use the pink battery outline on PocketC.H.I.P. to help you orient the battery placement.
Once the battery is secure, reconnect the battery’s JST-connector to PocketC.H.I.P. and attach the back of the case.
Note: Due to the larger screen size, the old bezel will not fit.
Flash C.H.I.P. using the online flasher. It’s counterintuitive, but don’t use a PocketC.H.I.P. image for this project. Currently only the C.H.I.P. 4.4 GUI and the C.H.I.P. 4.4 GUI No Limit images support this hack.
Once the flashing is done, put C.H.I.P. back into PocketC.H.I.P.. Attach a USB keyboard and mouse dongle to PocketC.H.I.P. and power it on. The display will illuminate and you’ll see a distorted, double image. This is because PocketC.H.I.P. is using the 480×272 resolution config file. Though the screen looks funky, the wireless mouse and keyboard will work as you’d expect.
Connect PocketC.H.I.P. to your home network and then open the Terminal application.
Note: If you’re new to the C.H.I.P. image, consult the docs for help with WiFi setup.
Download the config file and save it as xorg.conf.
wget -O xorg.conf http://bit.ly/2cpG2xV
Copy the file to /etc/X11/xorg.conf.
sudo cp ./xorg.conf /etc/X11/xorg.conf
Restart lightdm to reload X11 and utilize the new configuration file.
sudo systemctl restart lightdm
That’s it. Now your PocketC.H.I.P. will work with the larger screen size and all the settings will last even if you reboot the device.
However you decide to use the larger resolution on your PocketC.H.I.P., be sure to share it with the community. Post in the forum, share screenshots on Twitter, or mention your favorite application in the comments below. Happy hacking!