Is it bigger than a stamp? It depends on where you are and what stamps you have on your envelope. M5Stamp (M5Stack Store) is the smallest ESP32 based development board in the M5Stack family cutting the footprint of the M5Stack Atom (M5Stack Store, Banggood, AliExpress) by a fair margin. It’s thin, tiny and currently in my possession early thanks to the brilliant PR team at M5Stack.
Who doesn’t like early access right?
M5Stamp – not for everyone
Unlike almost all other devices from M5Stack, M5Stamp requires a bit of DIY before you can get started. I can’t image anyone taking on this board type without the will to solder things. You can make your life easier and order an M5Stack Kit, that includes FTD Programmer that docks into M5Stamp or pick the DIY path, soldering the pins yourself and use whatever FTD Flasher you have at hand. Either way, best have a good soldering iron about with a pointy tip – something like MiniWare TS80P (review) is a perfect tool for the job.
It’s slightly bigger than a thumbnail, yet M5Stack managed to pack a few features in and break out several GPIOs to make your adventures easier. It uses a slimmed-down ESP32 PICO D4 which has a footprint of 7x7mm. Other than a smaller footprint, lower power consumption and an integrated hall sensor and temperature sensor – it’s a standard ESP32 board with 2.4GHz WiFi and Bluetooth 4.2.
It’s only fair, that I include specifications here so you don’t have to venture far:
Other M5Stack products talked about in detail:
- M5Stack Core
- M5Stack Core 2
- M5Stack UnitV2
- M5Dial
- M5Stack Atom Matrix (pending)
Specification
- ESP32-PICO-D4
- Flash 4MB
- 5V @ 500mA
- WiFi 802.11 b/g/n & Blutooth V4.2 BR/EDR and BLE
- 18 * 24 * 4.4mm
- Programmable physical keys x 1
- Programmable RGB LED (SK6812) x 1
- 12 GPIOs
Comes with a familiar sticker 
Looks big, but M5Stamp is tiny
Power consumption
Apart from the small form factor, ESP32 PICO D4 brings pretty good power benchmarks. M5Stamp power specs include:
| Normal standby: | 5V@29mA |
| WIFI STA mode: | 5V@60mA |
| Bluetooth mode data sending status: | 5V@84mA |
| Deep-sleep mode: | 5V@0.35mA |
The device can be split into 3 interfaces (although you can define pins however you like in software). Included GROVE connector utilises 4 pins at the bottom of the device, serial transfer is done using 6 pins available on the right edge of the board and there are additional 9 pins on the right edge. The full GPIO map looks like this:
The built-in button is programmable and onboard LED flashes in all RGB colours. The machined thread in the middle of the PCB can be used as a mounting point. The package includes male/female headers so you can pick the preferred GPIO interface, the GROVE connector and a small Allen key to remove the shroud.
Getting started with M5Stamp
As the unit comes pre-flashed, to get started, all you need is to supply 5V and use created by M5Stamp WiFi AP point to access and configure the device. Take a note of the SSID created by the M5Stamp (M5-XXXXXXX) as XXXXXXX is your API key for UIFlow. Navigate to 192.168.4.1 once connected to the AP and enter your WiFi credentials.
The board will ask you to reboot it and you are ready to program it wirelessly through UIFlow. The M5Stamp has just been added there so select the board in options and you are ready to program it wirelessly.
Sample
From there, it’s the usual fun with wireless programming. Pick your path: UIFlow with visual programming or MicroPython. It’s not the most sophisticated example, but to get you started I made a random LED flasher.
The code below will set the LED to blue for 2 sec then use the button to activate random colour change or press and hold to stop the RGB madness.
Of course, if UIFlow and Micropython aren't what you are after, then M5Stack devices are supported in Arduino IDE, you can download that and use C++ libraries instead. After all, it is at its core yet another small form factor ESP32 based board.
If you don't want to use the default firmware (to save some space for your own code) you can erase it using M5Burner (don't worry, you can always flash it back), but to do so, you will need an FTD programmer.
To do it, you need to wire your FTD programmer in the following way:
| FTD Programmer | M5Stamp pins |
| VCC | 3V3 |
| RX | G1 (TX) |
| TX | G2 (RX) |
| VCC or 3.3V | EN (Enable) |
| GND | G0 (GPIO00) |
| GND | GND |
M5Stamp actually gave me an opportunity to try out my new pocket oscilloscope. Investigating the behaviour of CTI and DTR pins and checking the PWM signals of the M5Stamp gave me the inspiration to learn how to use an oscilloscope, as having one on your desk is very handy. If you want to know more about MiniWare DS213 - expect a review soon.
Final Thoughts
Once again, M5Stack made something cool out of a simple concept. You could get a random ESP32 dev board instead, but the size and wireless programming make it a very cool board to work with. With included GROVE connector, M5Stamp also opens access to a huge library of compatible sensors and expansion boards that you can use without any further soldering. So go on treat yourself. You know you want to! Let me know your thoughts in this Reddit thread.
🆓📈 - See the transparency note for details.
