M5Stack Card Computer review

By Ben Everard. Posted

The Card Computer, also known as the Cardputer, is an expansion of the M5StampS3. This base board has an ESP32-S3, which has a dual-core Tensilica processor running at up to 240MHz with 512kB of RAM, 8MB of flash, and Wi-Fi and Bluetooth connectivity.

Onto this removable board is a 56-key keyboard, 1 W I2S amp with speaker, 1.14 inch IPS screen, microphone, and 1400 mAh battery. You can also add more hardware via a Grove connector.

All of this comes in a sturdy plastic case which features Lego-compatible mounts and magnets for attaching to, well, anything ferrous. This is a huge amount of hardware for the price, so it should come as no surprise that it does have limitations: the 240 × 135 pixel screen is pretty small for most purposes; the buttons are hard to press, and the speaker is quite tinny. The hardware isn’t bad, but each piece is very basic. The advantage comes, not in any one piece of it, but in having it all together in a single, affordable device.

The ESP32 packs a big processing punch – it’s the most powerful of the common microcontrollers. It can, for example, emulate a Game Boy (Espeon). Given the processing power of this board, and the fairly minimal interfacing options (just two GPIO pins on the Grove connector), it really feels more like a computer than a microprocessor board.

While it doesn’t have an operating system in the conventional sense, some of the firmware can launch different apps, and fulfil the role of a rudimentary OS. One slight note of caution to consider here: while 512kB of RAM is a huge amount by most microcontroller standards, many other ESP32 boards have additional PSRAM, which the Cardputer does not. In some memory-hungry applications, you might find it more limited than other options.

You can program the Cardputer via the ESP-IDF, or Arduino. The example code is a bit lacking, and it’s not the easiest microcontroller to get started with – so we wouldn’t recommend this for beginners – but if you’ve got a bit of experience with embedded programming, it should not present too many problems.

Fortunately, though, if you set out programming the Cardputer, you’re not on your own. There is an emerging community around this device that is based around a subreddit, and a Discord server. They’ve created a few useful additions to the official firmware, including a MicroPython build (and app launcher called MicroHydra, a binary app launcher, and some modifications to the official firmware.

Form or function? The big question, in our mind at least, is what is the Cardputer for?

We’re a bit perplexed that the makers added Lego-compatible mounts and magnets, but not mounting holes. This means there’s no way of bolting it down to anything. The 56-key keyboard obviously gives you a lot of buttons to press, but they’re not particularly nice buttons and, with such a small screen, it’s hard to do much useful text entry.

There are a few niches that this could fit into well. The Grove-compatible connector means that you can plug in some sensors and it could be a bit of a Swiss Army knife for data collecting. It could also be useful for running Python scripts on the go if you need to interact with some networked hardware. Given its slightly cyberpunk look, we could definitely see it fitting into some cosplay outfit or prop, but the lack of a secure mounting option makes that a bit more tricky than it needs to be.

It could certainly be a fun project for becoming more familiar with the ESP32 microcontroller in general, or the M5Stack specifically. The board at the heart of the Cardputer is removable, so if you prototype something that needs only a portion of the hardware, you could pop it out and just connect up what is required.

In all these cases, it feels a bit like we’re making up a potential project because, in truth, we like the Cardputer. What it lacks in utility, it makes up for in fun. Perhaps this is simply because this reviewer has done too many orbits around the sun, but the Cardputer seems like exactly what he thought the future would be like when he was younger.

In many ways, it’s like a 1980s home computer but shrunk down to miniature size, and that was what we thought technological progress would be like. Yes, almost all the examples we’ve seen could be done better by a phone app, but somehow, that just wouldn’t be the same.

We don’t want to second-guess your projects, so you’ll have to work out for yourself if it can be useful to you. Some products, though, are worth it simply because they make you smile, and for us, the Cardputer is one of these. It might not be the most practical microcontroller development board around, but we love it anyway.



It’s a fun gadget, but we’re not sure what to use it for.


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