by Diodes Delight

A tiny-but-mighty open-source carrier board for the Raspberry Pi CM4

View all updates Jul 06, 2021

Production Delays

by Timon

Production is progressing on multiple fronts. I submitted my final design files to my PCBA fab four weeks ago. I’ve also been in contact with a fab to produce recyclable paper packaging for Piunora, and I just got pictures for the samples that I ordered. Those samples arrived at my main production fab so they can test packing up the final production prototypes once they are ready.

I heard back about the final PCB prototypes, and the fab incorporated my requested changes regarding PCB panelization. Unfortunately, they did not fix the issues with the silkscreen quality that I raised previously. They are aware and are re-running the boards now for free, but that means a delay of two weeks before my fab can receive the new PCBs and begin assembling them (which takes about three days). The production schedule was already quite tight with the original deadline but this two-week delay is definitely pushing our delivery estimate.

Unfortunately these things happen, and I’m not sure if they can be fully resolved with the next iteration. So I’m currently skeptical if, in two weeks time, I will get back an acceptable result regarding the silkscreen.

Silkscreen is unfortunately something many PCB fabs don’t take that seriously, given that it’s a largely cosmetic feature as long as it’s somewhat readable. The quality of the PCBs was otherwise superb but it seems they have been using an inkjet process for these prototypes and forgot to do it with the silk screening method as they had promised me with these final prototypes. Silkscreen printing usually yields much better results compared to ink jet printing, which is really only used with quick turn prototypes where creating a silkscreen tool is often not worth the effort and tooling cost.

TLDR: I will unfortunately have to push back my delivery estimate. At this point, it is hard to say how long the delays will be. If the prototypes that are coming back next week look good, then my PCBA fab can place the components and send me everything for final verification. If I don’t find additional critical issues at that point, I can give the release for mass production, which will take about three weeks. That best case scenario would have me shipping boards to Mouser at some point in the first half of August.

As many of you know, however, things seldom go perfectly, so I do anticipate additional, smaller hiccups. (Prolonged customs issues are not uncommon, for example.) As a result, I have set the projected ship date date to early October, based on the assumption that I will be shipping products to Mouser by early September. It can be difficult to anticipate how quickly items will be stocked into Mouser’s inventory, but that is definitely a conservative estimate.

I will of course keep you updated and let you know should things move along ahead of schedule or if further delays occur.

Thanks for your patience and for all of the encouraging messages from those of you who are waiting for your Piunoras.

About the Author


timonsku  ·  timonsku

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Product Choices


Piunora Pro

A compact, feature-rich CM4 carrier board


Piunora Lite

Perfect if you need the slimmest possible form factor. Includes all features of Piunora Pro except for the camera connector and the PCI-e M.2 port.


M.2 B-Key 2280 Extender

Expands Piunora's M.2 port to accommodate full-length 2280 peripherals. Keep in mind that such devices are quite a bit longer than Piunora itself, so they might look a little awkward hanging off the end there. But, if you have a cool idea that depends on a 2280 M.2 accessory...this is the product for you.


Raspberry Pi CM4 (Lite, Wireless, 1 GB RAM)

From the Crowd Supply Basics project.

Something for your Piunora to carry.

This CM4101000 variant of the Raspberry Pi Compute Module 4 is a System on Module (SoM) containing an ARM quad-core Cortex-A72 processor, 1 GB RAM, 2.4 and 5 GHz 802.11b/g/n/ac Wi-Fi and Bluetooth 5.0, and supporting power circuitry. Does not include eMMC flash.


Raspberry Pi CM4 (8 GB eMMC, Wireless, 2 GB RAM)

From the Crowd Supply Basics project.

Something for your Piunora to carry. The Piunora microSD card does not work when using eMMC CM4 variants.

This CM4102008 variant of the Raspberry Pi Compute Module 4 is a System on Module (SoM) containing an ARM quad-core Cortex-A72 processor, 2 GB RAM, 2.4 and 5 GHz 802.11b/g/n/ac Wi-Fi and Bluetooth 5.0, 8 GB eMMC flash, and supporting power circuitry.


Heatsink for CM4

You can operate the CM4 without a heatsink just fine, but if you have some extra-heavy computation to do, then a heatsink can help prevent thermal throttling of the SoC. Includes a mounting footprint for a 30 mm fan (not included) should you want to integrate it into an enclosure or take your CM4 to even greater extremes of computation. Also includes a set of stacking pin headers to accommodate expansion boards.


microSD Card

From the Crowd Supply Basics project.

Boot media for the "Lite" (CM4101000) variant of the CM4. We recommend 64 GB or smaller.

An industrial-grade memory card with extended endurance.


RPi CM4 Wi-Fi Antenna Kit

From the Crowd Supply Basics project.

An omnidirectional 2 dBi gain 2.4/5 GHz Wi-Fi antenna with panel-mounting hardware and an approximately 7.5" (19 cm) cable to connect the antenna's SMA connector to the CM4's U.FL connector. It is "certified for use with the Raspberry Pi Compute Module 4".


Diodes Delight

An open source hardware company and consultancy

Timon Skerutsch



PCB Fabrication & PCB Assembly

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