The ProS3 u.FL is an updated development board from Unexpected Maker featuring Espressif’s latest ESP32-S3 microcontroller. The main feature of this chip is the 2.4 GHz 802.11b/g/n Wi-Fi and Bluetooth 5 support. We opted for the version of the board having a u.FL connector instead of an on-board chip antenna. This allows the maker to attach whatever antenna is most appropriate for the project, and mount it away from the microcontroller board. Makers who don’t need this feature can get the version of the board with a soldered-on chip antenna.
Although this board is long and skinny, it is not in Adafruit’s Feather form factor. For that, you will want the comparable FeatherS3. The different form factors for ESP32-S3 boards are conveniently compared on UM’s website. This board does have a LiPo battery connector at one end, but it is a Molex MicroBlade connector, rather than a JST. There is an on-board LiPo charging chip that is activated when the board has power. It also has a STEMMA QT port for attaching I2C based peripherals. There is an RGB LED that the user can use for status indication. The board has castellations for surface mounting in addition to holes for soldering in headers. The skinny form factor makes this board very breadboard-friendly.
The ESP32-S3 has a 32-bit, dual core, 240 MHz processor. The ProS3 supports the ESP32-S3 with 16 MB of external flash and 8MB of PSRAM. The PSRAM is a slower, external RAM that complements the on-chip 512kB of SRAM. Use of the PSRAM requires explicit instructions in your code via functions like ps_malloc() so it is usually used for large buffers that won’t fit in SRAM.
The ProS3 comes with CircuitPython already installed and ready to use. When the board is connected to a computer via its USB-C connector it will mount as a mass storage device. You can then drag and drop python files onto the drive to program the board. CircuitPython is one of the easier ways to program the ProS3, and is well documented and supported by Adafruit. Other supported programming environments include Micropython, Espressif IDF, or the Arduino IDE. Be sure to read the guide to programming environments on Unexpected Maker’s website for important notes about support in different versions of these environments.
To test out the board, we got it up and running in the Arduino IDE. It was simple to go to the Boards Manager, search for ESP32, and install the package from Espressif systems. Your system should install a set of example sketches. Once your board is connected and the correct board type is selected from the Tools menu, the examples will appear in File->Examples. I recommend compiling and running the Wifi->WifiScan example to test your ability to upload to the board and find your Wi-Fi router. If you have trouble finding the examples or uploading them to the board, the solution is usually to force the board into bootloader mode by holding the BOOT button while momentarily pressing the RST button. You might have to manually reset the board again via the RST button after the sketch uploads and you will probably find that the board moves between COM ports when it begins running a sketch. This means you will have to re-select the board’s port in the Tools menu before you can connect to it with the Serial Monitor.
In all, the ProS3 is a great board for prototyping if you need Wi-Fi or Bluetooth. It’s well supported in several programming environments and has a large user base.
