It was a complete oversight on my behalf for not promoting the crowdfunding campaign for the follow-up to Home Assistant Blue, Home Assistant Amber, until now. Luckily, Home Assistant’s popularity is so widespread that the campaign has already surpassed its goal and fans have so far pledged over US$175,000 of the US$140,000 required to launch the product on Crowd Supply.
At the heart of Home Assistant Amber is no longer an off-the-shelf and ready-to-use board, but the Raspberry Pi Compute Module 4. It boasts the same specs as the powerful Raspberry Pi 4 Model B, but has a PCIe Gen 2 x1 interface. That interface is important because it allows for an M.2 expansion slot, but it does unfortunately come at a cost, which I will be discussing in this article. The Raspberry Pi Compute Module 4 in Home Assistant Amber sits on top of a custom-built board, which has some other niceties included.
Table of contents
- Table of contents
- What is the Raspberry Pi Compute Module 4?
- Where Home Assistant Amber falls flat
- Home Assistant Amber vs. Home Assistant Blue
- Where Home Assistant Amber shines
What is the Raspberry Pi Compute Module 4?
There has been some confusion around the Raspberry Pi Compute Module 4, so before moving on, a quick explainer on the board that is powering the upcoming Home Assistant Amber. To put it simply, the Raspberry Pi Compute Module 4 is a Raspberry Pi 4 Model B board, without any ports. There is no USB, HDMI, or Ethernet port to be found on it. Not even a power adapter. The missing ports also mean that certain controllers, such as the PCIe to USB 3 bridge, aren’t needed, making it only 55 mm x 40 mm in size. The Raspberry Pi Compute Module 4 is not meant to be used as a standalone device, but instead is sold to industry partners for embedded applications, such as Nabu Casa, who is building Home Assistant Amber.
The Raspberry Pi Compute Module 4 comes with the same quad-core Cortex-A72 CPU at 1.5 GHz and Broadcom VideoCore VI graphics processor found in the Raspberry Pi 4 Model B. Nabu Casa isn’t the first manufacturer to feature the Compute Module 4 in such an application. For example, Sharp NEC Display Solutions offers it as an accessory for some of their monitors.
Because the Raspberry Pi Foundation intends to sell the Compute Module 4 in bulk, there are many variants available. Once you are buying thousands of boards, a couple of dollars difference can make a significant budgetary impact. In total, there are 32 variants. These differ in three areas:
- Wireless (Wi-Fi and Bluetooth/BLE): Yes or no
- RAM: 1 GB, 2 GB, 4 GB, 8 GB
- Onboard storage: Lite, 8 GB, 16 GB, 32 GB
Home Assistant Amber will be compatible with every available variant. You could start with one of the cheaper options, and as you outgrow it, switch to one of the more powerful boards. However, I would definitely recommend going with the 8 GB RAM and 32 GB storage option from the beginning. Once you get in to home automation, you will never stop finding new projects to tackle.
Where Home Assistant Amber falls flat
Before talking about how great of a device Home Assistant Amber is, I would like to point out a few downsides to the platform. While Amber is undoubtedly already a success, and I hope to see new versions once the Raspberry Pi 5 arrives, there are also ways of supporting the Home Assistant project, without buying any official hardware. If you love this project, I implore you to sign up to Home Assistant Cloud.
Now that we know all about the board powering Home Assistant Amber, let’s talk about some reasons you might not want to buy it. In the introduction, I mentioned that the M.2 expansion slot comes at a cost, and that cost is the lack of USB 3.0 ports. Only being able to use USB 2.0 could become an issue if you were to populate the M.2 slot with a Google Coral Accelerator, and needed somewhere to store footage that is recorded by an NVR such as Frigate or motionEye. Likewise, It is possible that your setup could surpass what is offered in the cheaper Raspberry Pi Compute Modules.
- A USB accessory that brings machine learning inferencing to existing systems.
- The on-board edge TPU Coprocessor is capable of performing 4 trillion operations (tera-operations) per second (tops), using 0.5 watts for each tops (2 tops per watt).
- USB-C (3.0) connector for data and power.
It is for that reason that I recommend going with the Raspberry Pi Compute Module 4 with the most onboard storage. That way, you don’t necessarily have to use the available M.2 slot for storage expansion. This limitation is due to the Compute Module 4, and as such, Nabu Casa can’t circumvent it.
Finally, and the most devastatingly, Home Assistant Amber will only start shipping in June of next year. Luckily, the hardware isn’t going to be outdated once it ships. It is highly unlikely that the Raspberry Pi 5 will make an appearance by then, as the team hasn’t even begone work on it yet. However, if it were to appear in the next year, it would be a significant upgrade over the Raspberry Pi Compute Module 4 in Home Assistant. It potentially will have more than 8 GB of RAM, quicker USB connectivity, more powerful Wi-Fi and 2.5 Gb Ethernet.
Home Assistant Amber vs. Home Assistant Blue
Home Assistant Blue could be called the predecessor of Home Assistant Amber, as it was the first piece of official hardware. But as it wasn’t customized in any way, Amber can likewise be considered the first of its kind. Home Assistant Blue featured an ODROID-N2+ off-the-shelf board, with a custom-made case. It came prepackaged with 128 GB of eMMC memory, but no modifications. Besides the case, it could be easily replicated by anyone.
Despite the comparison below seemingly favouring the ODROID-N2+ in Home Assistant Blue, the Raspberry Pi Compute Module 4, and all other Raspberry Pi models, have one major advantage over every alternative: Support. In addition to that, the Raspberry Pi Foundation currently seems to be having better luck dealing with the ongoing chip shortage. This is possibly in part due to their choice of older components.
- Uses the faster, stabler, and more energy-efficient Zigbee 3.0 protocol.
- Has a dot-matrix E Ink screen, making it legible under direct sunlight.
- Can be magnetically mounted to any surface.
- Powered by two CR2450 button cells which can last for up to a full year.
- 0.1° C temperature resolution, 1% humidity resolution, and 1ppb or 0.01 mg/m³ TVOC resolution.
With Home Assistant Amber, you will also need to buy fewer accessories, as it already includes a radio for Zigbee and Matter, more on that later. Blue also requires the use of one mare cable than Amber, as the latter supports Power-Over-Ethernet.
Raspberry Pi Compute Model 4 vs. ODROID-N2+
In terms of the processing power, the ODROID-N2+ is better than the Raspberry Pi Compute Model 4 on paper. It features a CPU with four newer, and smaller, Cortex-A73 cores, whereas the Raspberry Pi makes due with four Cortex-A72 cores. The ODROID-N2+ also has two Cortex-A53 cores, in a big.LITTLE configuration.
The two low-power cores, along with the smaller 12 nm big cores, make the ODROID-N2+ more power-efficient when compared to either the Raspberry Pi Compute Model 4 or Raspberry Pi 4 Model B, who’s cores which use a 16 nm fabrication process.
The specifications of the graphics processer paint a similar picture: The ODROID-N2+ uses a Mali-G52 GPU, with six Execution Engines and a clock of 800 MHz. The Raspberry Pi Compute Module uses a Broadcom VideoCore VI GPU, clocked at 500 MHz. There is much speculation as to why the Raspberry Pi uses Broadcom’s GPUs and not Mali’s. A Raspberry Pi Engineer cleared up this speculation with a short, but to the point, explanation in a forum post: At the time the Raspberry Pi was in development, Broadcom’s VideoCore GPUs were more powerful, and they have an integrated ISP, LCD drivers etc., which the Mali does not.
Home Assistant Amber vs. Raspberry Pi 4 Model B
What is stopping you from buying a Raspberry Pi 4 Model B with a fancy case instead of Home Assistant Amber? In all honesty, nothing. As already mentioned, the SoC on both boards is identical. There are a few extras, which the vanilla Raspberry Pi 4 Model B lack:
- There is no M.2 expansion slot, meaning you need to run your OS of an SD card, or external storage. Additionally, the Raspberry Pi 4 Model B does not have any onboard storage.
- Home Assistant Amber has a Zigbee radio chip with support for OpenThread and Matter built in (more on that in a bit).
- The Raspberry Pi 4 Model B requires additional purchases, such as a case, cooling, and power supply.
- Home Assistant Amber supports the Home Assistant project and its success could lead to future revisions.
Does that mean you should throw out your Raspberry Pi 4 Model B, as soon as Home Assistant Amber is available? Absolutely not. You can buy cases, such as the popular Argon ONE, which have room for an M.2 SATA drive and come with fantastic and efficient cooling options. An SATA drive won’t be quite as fast as an NVMe drive in Amber, but it should be able to run Home Assistant without any hiccups.
Additionally, compatible adapters are bound to appear, once Matter appears. There is nothing holding you back from building your own flavour of Home Assistant Amber. Though the latter supports the further development of Home Assistant and comes pre-assembled in a custom enclosure.
There is, in theory, also a Google Coral USB accelerator available , which you can connect to your Raspberry Pi 4 Model B, though it does appear to be permanently sold-out. While the highest-end M.2 accelerator does feature two, instead of one, Edge TPUs (Tensor Processing Unit), the USB option should be able to handle a decent number of streams.
Where Home Assistant Amber shines
Home Assistant Amber will arrive pre-assembled at your doorstep, with Home Assistant pre-installed. There is no need for you to flash an SD card, or assemble a case. Everything you need is right there, packed in to a neat little box, which reminds me of the limited edition original Xbox and Game Boy.
If you are not a fan of cables, Home Assistant Amber has another treat for you: PoE support. Power-over-Ethernet allows you to provide both power and data to the board using a single cable. That is, if you have a capable switch.
Finally, Home Assistant is fully embracing Zigbee and Amber is the perfect example of this: On the board there is a Silicon Labs MGM210P Mighty-Gecko-Modul. This integrated radio currently supports Zigbee and will, at some point in the future, also enable communication with Matter devices. While there were some concerns about Home Assistant Amber not supporting external antennas, balloob, the founder of Home Assistant and Nabu Casa, was quick to point out that the ceramic antenna it has performed better than external Zigbee dongles.