Just two months after we learned of the Raspberry Pi Compute Module 4S, another Compute Module variant has appeared online. Twitter user Pi O in your Pocket has images of a Raspberry Pi Compute Module 3 with what appears to be the Raspberry Pi Zero 2 W's SoC package. The cryptically named Raspberry Pi Compute Module 3E has been revealed and it seems to be powering a Wallbox electric vehicle charging point.
Just taken delivery of a shiny @wallboxchargers EV charger and spotted the super shiny new @Raspberry_Pi CM3E in there with its super swanky combined CPU/RAM package 😎 pic.twitter.com/oEUqKPMwTKJune 9, 2022
Right now the Raspberry Compute Module 4 is the most powerful and sought after Compute Module variant. But you will have a job getting your hands on one given the current shortages. For industrial customers, who value compatibility and continuation of service over power, the Compute Module 4 is still far away in their upgrade path.
The Raspberry Pi Compute Module 3E uses the older SODIMM form factor, which means it can be dropped into carrier boards including the official IO board and some third-party boards. In the images we can see the Compute Module 3E being used with Wallbox's own carrier board, designed for use in its range of EV charging stations. The carrier board seems to have an IDE connector. Using an IDE drive seems to be a stretch of the imagination, so our best guess is that it is a GPIO breakout for the 40 pin GPIO.
From a cursory search of the Raspberry Pi website we found no information on this new board. We also looked at Raspberry Pi's GitHub page, the same page which highlighted the existence of the Compute Module 4S, but alas we couldn't find any information on the Compute Module 3E. Even looking inside the Compute Module 3 device overlay returned nothing. So let's do a little detective work based on what we can see.
The system on chip (SoC) reference matches that of the Raspberry Pi Zero 2 W. RP3A0-AU is the same SoC that brought much needed performance to the Zero form factor. Granted it was somewhat lacking in RAM, but the RP3A0-AU has the CPU power equivalent of the Raspberry Pi 3 but in a much smaller form factor. On the reverse of the Compute Module 3E we can see a Samsung KLM8G1GETF-B041 eMMC chip with 8GB of storage, plenty of storage for a basic Raspberry Pi OS Lite install, or a custom OS based on a server image. Also on the reverse of the Compute Module 3E is a date code, 4221, identifying that the PCB was made in the 32nd week of 2021, and it was made in PRC (People's Republic of China). So this is not a UK-made board from Sony's Pencoed factory, the site where millions of Raspberry Pi have been made.
| Header Cell - Column 0 | Raspberry Pi Compute Module 3E | Raspberry Pi Zero 2 W | Raspberry Pi 3 | Raspberry Pi Compute Module 3 |
|---|---|---|---|---|
| CPU | BCM2835 Arm v7 Quad Core Arm Cortex A53 running at 1 GHz? | BCM2835 Arm v7 Quad Core Arm Cortex A53 running at 1 GHz | Quad Core 1.2GHz Broadcom BCM2837 64bit CPU | Quad Core 1.2GHz Broadcom BCM2837 64bit CPU |
| RAM | 512MB LPDDR2? | 512MB LPDDR2 | 1GB | 1GB |
| GPIO | Via SODIMM | Standard 40 Pin (unsoldered) | Standard 40 Pin | Via SODIMM |
| Connectors | Carrier board dependent | Mini HDMI Micro USB power Micro USB 2.0 data Camera connector (Requires adapter) | 4 x USB 2.0, Ethernet, HDMI, Composite, Micro USB power | Carrier board dependent |
| Wi-Fi / Bluetooth | None that can be seen | 2.4 GHz 802.11b/g/n Wi-Fi with PCB antenna Bluetooth 4.1, BLE | BCM43438 wireless LAN and Bluetooth Low Energy (BLE) | Carrier board dependent |
| Dimensions | 67.6 x 31 mm | 65 x 30mm | 85 x 56mm | 67.6 x 31 mm |
If we assume the RP3A0-AU SoC is the same, the Compute Module 3E appears to be an even match for the Raspberry Pi Zero 2 W. We should have four competent Arm CPU cores running at 1 GHz, and a rather meagre 512MB of RAM. Enough for an embedded application, but not something that we would actively seek for home use.
The use of the Compute Module 3E in Wallbox's EV charging stations is nothing new, but this variant is and we can only assume that the Compute Module 3E is an industrial only product, which leads us on to another variant that caught our eye.
There is another "industrial" Pi, the Compute Module 4S. Essentially, it is the Compute Module 4, crammed into the older SODIMM form factor. Granted we don't get the full Compute Module 4 experience. We are limited to 1GB of RAM and there is no Wi-Fi. But we do get the full Broadcom BCM2711 quad-core 64-bit Cortex-A72 (Arm v8) CPU running at 1.5 GHz. Industrial customers wishing to add a little more "oomph" to their products without the extra cost of new carrier boards may choose this upgrade path.
We have contacted Raspberry Pi for comment and are awaiting confirmation of our findings. This story will be updated once we have more information.
