C64Pico part 3

Last Updated or created 2024-05-01

Today we worked on this project again. (Bigred and me)

There were some problems we needed to fix since last time:

  • It was quite hard to get the correct parts.
    Our display connector was only fitted with connection pins on the wrong side of the connector. (up/down)
    So I bought a connector with both positions populated.
    So we had to replace this hard to solder (40 pin) connector.
  • It was not clear what the orientation should be of the atmega328pb.
    We looked at the pinout, and followed the VCC/GND. But these are also available of the opposite side of the chip. (We missed that)
    Later, we saw a tiny line on the PCB, which showed the pin 1 placement.
    So we had to remove and replace the chip.
    When turning on the power, (with incorrect placement) probably fried R5 (10k resistor), on both our boards.
    Had to replace those also.
  • Programming the atmega328pb was not easy, see below fixes.
  • Compiling the pico firmware resulted in a black screen.
    Below the fixes I had to make to get the screen working.

Other things still to fix.

  • Bigreds screen.
  • atmega328p didn’t work for Bigred, so probably needs to replace with the pb version.
  • My battery controller is not charging.
    See bottom of page
  • Some of my buttons are working. The pewpew and some of the cursor keys (not as I expect, there are some up/down issues)
    And none of the other keys are working.

Some other things we noticed.

  • sdcard: remove partitions, format using mkfs.exfat
    Create a c64 directory on this filesystem where you can put the d64 files!
  • 0402 SMD is far too small for me.
    There is enough room on the board to use 0805 for example.
    Even THT is possible, there are only a few components.
  • Some components are TOO close together, removing a component resulted in other small parts disconnecting also.

My friend Bigred said: If I can see it, I can solder it.
But it is not easy. This probably keeps a lot of people from building it!

Below the diff from the source we got from:


UPDATE 20240501: We needed to clone the c64pico branch!

git clone -b c64pico https://github.com/silvervest/MCUME.git

Then it worked with the screen and keyboard!

Programming the atmega328pb using usbasp

Link above shows the programmer.

To get your Arduino IDE up and running

  • Open the Arduino IDE.
  • Open the File > Preferences menu item.
  • Enter the following URL in Additional Boards Manager URLs:https://mcudude.github.io/MiniCore/package_MCUdude_MiniCore_index.json
  • Open the Tools > Board > Boards Manager… menu item.
  • Wait for the platform indexes to finish downloading.
  • Scroll down until you see the MiniCore entry and click on it.
  • Click Install.
  • After installation is complete close the Boards Manager window.

Above settings worked for me, maybe you can also try Programmer: usbasp (slow)

First install the bootloader.

When compiling the keyboard program of silvervest, you can find “Upload using programmer” in the Sketch menu!


Maybe I’ve got a problem with the ground plating of the charger.
Also very hard to solder the sides!

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