UNO

bruno ESP32-S2-Mini

Break-out board for ESP32-S2-Mini to Arduino UNO style base board.

This PCB allows you to experiment with various Arduino 3.3V compatible shields while using a cheap and powerful ESP32-S2-Mini board.

This board can only handle IO voltages up to 3.3V, therefore not every Arduino shield is compatible.

The features are as follows:

• ESP32-S2-Mini has more memory, more flash and faster CPU speed compared to Arduino UNO
• no additional components (except the optional LED on GPIO 39)
• simple to assemble (just solder the Mini board and Arduino GPIO headers).
• Digital IO numbering mostly follows AVR UNO pin nmubers
• Extra GPIO pins exposed on the 6-pin side header
• USB-C powered

Differences comapred to Arduino UNO

• 3.3V IO logic only!
• IOREF pin hardwired to 3.3V
• no external AREF, use the internal Analog reference of ESP32-S2
• only 5 Analog pins on the Analog header (A5 is digital only)
• extra analog pins on Digital header pins 1 - 13 (ADC1_0 - ADC2_2)
• no TTL Uart on digital pins 0 and 1 (however the serial input/output is mapped to the USB port)
• The reset pin on Arduino board is not connected to the ESP32-S2-Mini. There is a convenient pad placed next to the S2-Mini reset button, so if you need the external reset functionality you can wire the S2-Mini reset button and the reset pad.
• The S2-Mini has an onboard LED (located between the USB connector and the '0' button) that is connected to GPIO 15 (Arduino UNO A1 pin). That might cause issues with some designs. In such case remove the LED or the current limiting resistor on the S2-Mini board to fix the issue (the LED will stop working obviously).
• Note that the 3.3V rail is powered by a small onboard LDO (voltage regulator) which also powers the MCU. If you need to use higher number of peripherals on the 3.3V power rail then consider adding another LDO (supplied by the 5V rail) to your design/shield. Generally speaking, for few LEDS and a couple of extra ICS (like accelerometer, sensors etc.) the LDO is OK and you'll not need to add an extra LDO.
• WiFi functionality is untested. It might work, but the PCB antenna is close to the base board so the transmit/reception will not be great. If you'll use a shield that covers the antenna the maximum connection distance will be even shorter.

Arduino IDE setup

Install the ESP32 platfrom from Espressif in boards manager. Then select the Board as 'ESP32S2 Dev Module'. The rest of the board configuration options is as follows:

• Ensure "USB CDC On Boot" is Enabled, so that you have the Serial port mapped to USB.
• The sketch upload works automatically, no need to press reset or boot buttons (tested with IDE 2.2.1).
• Note that my CPU frequency is lowered to 40MHz. This might improve compatibility with UNO sketches when they use bit-banging technique.