S2 Tiny (26uA in deep sleep)

1 year ago

Profile:S2 Tiny Breadboard friendly minimal dev board for ESP32-S2 Wrover or Wroom

Open source license: Public Domain

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Description

S2 Tiny

Breadboard friendly minimal dev board for ESP32-S2 Wrover or Wroom

Features

  • Small footprint (many pins are not accessible)
  • Designed for hand soldering (0805 footprints)
  • MCP1700 (6V max) or MCP1702 (13V max) voltage regulator with very low quiescent current for battery operation
  • Draws about 26uA in deep sleep
  • Cheap P-Channel MOSFET for reverse polarity protection without significant voltage drop
  • SPI (MISO, MOSI, SCK) and default Arduino IDE I2C pins are accessible
  • DAC pins are accessible
  • Pins necessary for flashing are accessible
  • There's a large VIA in the middle of the heat transfer ground pad, so you can make contact between the ESP32-S2 module and the board (not strictly necessary, not sure if it works as intended anyway)

Voltage regulator

While the MCP1700 is rated for max 250mA continous current, it is able to supply 550mA pulsed current. In combination with 22uA caps this seems to be enough for the ESP32-S2.

The board does not include a fuse, but the MCP1700 should shutdown automatically on overcurrent (untested).

Another ESP32-S2 (DevKit by OLIMEX) with this voltage regulator can be viewed here: https://github.com/OLIMEX/ESP32-S2-DevKit-LiPo/blob/main/HARDWARE/ESP32-S2-DevKit-Lipo-Rev.B1/ESP32-S2-DevKit-Lipo_Rev_B1.pdf

Flashing

To flash the board use a serial connection, e.g. via FTDI board connected to RX/TX/GND, e.g. in combination with Arduino IDE. You need to connect GPIO0 to GND and push the reset button before flashing.

Currently I'm using the esp32s2 tree of the Arduino core for the ESP32: https://github.com/espressif/arduino-esp32/tree/esp32s2

Tutorial how to setup Arduino IDE for ESP32-S2 https://github.com/OLIMEX/ESP32-S2-DevKit-LiPo-USB/blob/main/DOCUMENTS/Tutorial-ESP32S2.pdf

(from https://www.olimex.com/Products/IoT/ESP32-S2/ESP32-S2-WROVER-DevKit-USB/open-source-hardware)

Photos

R0039409.jpgR0039415.jpgR0039385.jpgR0039393.jpgR0039178.jpg



Documents

S2 Tiny schematic copy copy

Open in editor

S2 Tiny PCB

Open in editor

BOM

ID Name Designator Footprint Quantity
1 3x6x2.5mm KEY1 KEY-3.0*6.0 1
2 ESP32-S2-WROOM ESP32-S2-WROVER ESP32-S2-WROOM 1
3 10k R1 R0805 1
4 AO3401A Q1 SOT-23_L2.9-W1.3-P0.95-LS2.4-BR 1
5 MCP1700T-3302E/TT U1 SOT-23-3_L2.9-W1.6-P1.90-LS2.8-BR 1
6 100n C2 C0805 1
7 22u C1 C0805 1
8 1u C5 C0805 1
9 HDR-M-2.54_1x10 J4,J3 HDR-M-2.54_1X10 2
10 22u C3,C4 C0805 2

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