Example journal entry

Here's an example journal entry - it's a little long so I put it on a separate page.

It's for a retro game console I'm building that runs on a Raspberry Pi Zero 2W!

I find that writing journals like this can be pretty tedious, so one thing I recommend is just recording a vlog of what you did and then summarizing that instead. To that end though, you still need to include images and fairly detailed descriptions!

June 8: Got the screen to work!!

I got the raspberry pi to actualy display on the LCD! Can't believe it actually works

I based the wiring off of the pi-tin project originally, but they used an ili9341 display instead of the st7735r I was reusing from sprig. That meant that I had to figure out not only how they got it to display originally, but also how to modify that to use the ST7735R drivers instead

Fortunately for us, the pi-tin project actually documented how the software was set up! They actually cross-reference an adafruit script, which is a derivative of one from pimoroni.

In short, here's how the original method worked:

• Install FBCP (framebuffer copy) drivers, which captures whatever would've been outputted to HDMI and allows you to redirect it somewhere else
• Modify the dtoverlays (device tree overlay) in /boot/config.txt to use the built-in kernel drivers for the ILI9341
• Reboot. The framebuffer should automatically redirect everything to the display.

The main problem was then figuring out what parameters I needed to add to /boot/config.txt to make it work with the new display. I wasn't even sure if there were the right drivers built into the linux kernel!

Here's how I figured that out:

• the original rpi-fbcp repository mentions some sort of FBTFT driver
• a quick search links to this repository, which then mentions that the drivers were now in staging on the linux kernel
• a bunch more digging eventually leads me to stumble to this file: st7735r.c

Bingo. The drivers exist.

Anyhow, digging into the existing dtoverlays eventually led me to an st7735r generic overlay in the raspberrypi/linux repo! Using ChatGPT to then convert that to a dtparam, I eventually got video output:

The tl;dr is that raspberry pi provides the dtoverlay files for the ST7735R built in, so it's a matter of installing a framebuffer and redirecting that to the display in the /boot/config.txt file

Time spent this session: 6 hours