A OSHW Raspberry Pi CM4 carrier board in Arduino/Metro formfactor for electronics prototyping

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Piunora is a compact development board for electronics prototyping with Linux. It has a familiar form factor, legible pin labels, and a design that's well suited to space-constrained applications.

It is a carrier board for the Raspberry Pi Compute Module 4 (CM4). Essentially a tiny version of the Raspberry Pi 4 designed to enable custom form factor with the same System on a Chip found on the Raspberry Pi 4. Software running on a Pi 4 is fully compatible to a CM4 based device. Except for a different set of peripherals.
The CM4 is also available in options with eMMC memory which is much more reliable than traditional SD Cards.

Piunora has a lot of peripherals not found on traditional Pi Single Board Computers. Including a PCI-e M.2 port on the back, a dedicated ADC (MCP3008), QWIIC connector for easy I2C prototyping, WS2812 RGB LED and 2x User Buttons.

Making a Shield PCB is also a lot more user friendly than the large dense 40 pin header on the traditional PI's.

Features & Specifications

  • Arduino UNO R3 / Adafruit Metro compatible form factor (3.3 V logic, may not be compatible with all Shields)
  • PCI-e through M.2 B-Key connector on the rear of the board with dedicated 3.3 V / 3 A supply
  • Analog to Digital Converter (MCP3008)
  • On-the-fly switching between USB host (USB Type-A) and device mode (USB Type-C)
  • Qwiic/Stemma QT connector to easily interface with I²C devices
  • A full-sized camera connector that supports all Pi-compatible cameras
  • A full-sized HDMI 2.0 port
  • A WS2812 Smart RGB LED for user status
  • Optional Wi-Fi or eMMC options depending on your choice of CM4
  • Slim design with the Piunora Lite measuring 8-12 mm and the Piunora Pro measuring 11-13 mm
  • Two user-controllable buttons (including software that turns one of them into a safe-shutdown button)

Adobe Portable Document Format - 56.61 kB - 12/19/2021 at 22:37


  • Beta test under way, components ordered

    timonsku06/19/2021 at 17:38 0 comments

    By now all of the beta testers have received their units and have been playing with the board. I already got some valuable insight into software issues.
    In the meantime I was hustling to secure the stock for all the parts which was quite nerve wrecking due to many parts being out of stock for many months. In the end I found enough drop-in replacements so at least this first production run is secured!

    I have also been busy making all the last changes that I discovered since the last production prototype. Mostly silkscreen fixes and a few pin out changes (the pins that normally over a UART on Arduinos now actually has pins with hardware UART).

    I also sneaked in a little bonus feature for the adventurous hackers. You can now optionally mount a SIM card connector to use 4G/5G modem cards in the M.2 connector. I verified that this is actually possible, in this case you just need to close the USB jumper that I provided to re-route the USB-A port to the M.2 connector.

  • Next steps

    timonsku03/31/2021 at 11:57 0 comments

    Piunora has been in development for about 3 months now and has moved on to the pre-production run, if no issues arrive from that I will also release the design files. I know some are eager to take a look at those but I had bad experience with releasing unfinished designs so I'm sticking to verified designs.
    Once they are ready for release I will create a GitHub repo and add it to this project. So if you follow this project you should be notified about the release.

    I've been meaning to track the development on but it was just way to taxing to do this also besides actually working on it but I try to give you some of the background details after the fact to give you an idea how the development had progressed.
    Now the design is entering more the production phase and I hope I can give you more insights into that as it progresses.

    Piunora has entered its crowdfunding campaign yesterday on CrowdSupply and I'm really happy about all the excitement I have received throughout the day!

    If you are eager to get a Piunora the campaign is your best bet, it will receive boards first before any other distributors after the campaign.

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