Pi1541io Revision 4

The prototype batch of PCBs for revision 4 of the Pi1541io board didn’t take long to ship and it arrived from PCBWay while I was on vacation. Today, I finally managed to assemble one of the boards and everything seems to work great!Revision 4 is basically what the previous one should have been: an improved rev.2 with an added I2C connector for an OLED display. In this revision though, the I2C connector can be configured to accommodate different kinds of display modules.

Again, the BOM for this board is mostly identical to that of revision 2. But I’d recommend you get yourself a compatible display, too.

1   OLED Display with I2C SSD1306, 128x64px eBay (China) eBay (Germany)
1 J12 1×4 pin female header eBay (China) eBay (Germany)

When assembling the board, you need to make your choices and configure the solder bridges as described for revision 2. Additionally, you need to configure the I2C header using new solder bridges if you intend to use it.

Configure the I2C header.

  1. Choose whether to power the display module with 5V or 3.3V. You must not use 5V if your display module is lacking its own voltage regulator! If in doubt, choose 3.3V — it should work in basically all cases.
  2. Configure the pin order for your display module. You need to choose between one of GND-Vin-SCL-SDA or Vin-GND-SCL-SDA.
  3. If you configured your board to use the 7406 IC as a bus driver, you have the choice between using I2C bus 0 or 1 of the Raspberry Pi. If you opted for the “simple” layout without the 7406, you are limited to using I2C-0.

Example for a valid I2C configuration.

[Update] In the example image above, the I2C header is configured for 3.3V, I2C bus 1, and a display module with the pin order of GND-Vin-SCL-SDA.

The project sources will again be available on Github as soon as I find the time to update the documentation. In the meantime, you can already order your boards on PCBWay, if you like.

Update: Sources and Gerber files for revision 4 are now available on Github.


10 thoughts on “Pi1541io Revision 4

  1. Just found this project and it looks great. I just ordered some rev 4 boards from pcbway. Not really clear on how the solder bridges should be configured though. Do you bridge the left two pads top and bottom for GND-Vcc and the right two pads top and bottom for Vcc-GND pinouts? For bus 0 and bus 1 selection do you bridge all three pads? Thanks

  2. You are right, that could be clearer. I should add an example photo or drawing to clarify. Yes: Left two pads top and bottom for GND-Vcc. No: Left two pads in both boxes for bus 0, right two pads for bus 1.

  3. Can you share the Gerber files of revision 4?
    PCBWay is ignoring my messages on Facebook so now I want to place the order elsewhere.

  4. Yes, I will. The Gerber files will be included in the git repo. I still need to do some cleaning up there before I can push the latest changes, though. Maybe I’ll get around to that later today.

  5. @Okurka: As I told you before, I will share the Gerber files. But pushing me will not speed up the process.

  6. My first question nor your answer to it were showing when I posted my question a second time. I didn’t mean to push you, I simply thought my first question was blocked.

  7. You Sir, are a legend. I built an OLED-enhanced Pi HAT based on your Rev. 4 board, which was a joy to work on and works flawlessly. Thank you so much for all your hard work here, you’ve made a lot of old retro-heads very happy.

  8. Thanks Dan, I’m glad you like my board! But the praise mostly belongs to Steve for the actual Pi1541 project, of course.

  9. I just hand-built a Pi1541 board, and while looking for case STL files found this board. I think I’ll order a set and make some for friends. 🙂

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