The board was designed explicitly for the barometer instructable.

There are many variations of ESP32 development boards for DIY projects based on Expressif's ESP32 microcontrollers. Generally, it is excellent with a wide variety of these boards, but it also creates problems. ESP32 modules use from 20 up to 38 pin positions.

I can have lots of flexibility with a breadboard, but this solution is best for prototyping and testing circuit ideas.

I wanted a more semi-permanent solution but still some flexibility for my choice of modules. I also wanted a decent-sized 2.8” TFT SPI display and many different headers for I2C-bus connections.

Note: The development modules, breakouts, and display are only on the pictures to illustrate possible applications of the adapter board. This is not part of the offer.

Description The solution was to design an adapter printed circuit board (PCB) for a few popular ESP32s. Unfortunately, pins on ESP32 development boards vary wildly. But, with many female headers on the PCB, I can fit different vendor modules.

Further, I can use female headers or permanently solder the modules to the board.

The adapter board uses I2C for various pressure sensors. However, it can still be used for other I2C-based breakout boards, either directly if the pin order is identical or using DuPont wires to match individual signals.

Features

‘The Amazing ESP32 Adapter Board v1.x’ has five female header positions for the following ESP32 pin counts.

• 20 pins (for Unexpected Maker’s TinyPico ESP32)
• 12+16 pins (for Sparkfun’s ESP32 Thing Plus)
• 30 pins (for ESP32 unbranded module)
• 36 pins (for  DOIT ESP32 DEVKIT V1)
• 38 pins (for Expressif’s ESP32-DEVKITC-32D)

Carefully study the boards' schematics if you use other ESP boards for power, ground, and I/O-signals. The GitHub documentation has an ESP32 compatibility list maintained with tested development boards. Feel free to submit your module if it works on this adapter board, and I will keep the list up to date.

In addition, there are four female header positions for I2C breakout boards, the display position, and one additional header (J3) position. The display SPI connector and J3 are wired in parallel.

• 4, 5, 6, and 7-pin header positions for I2C breakout boards
• One 14 pins header position for the SPI TFT 2.8" color display
• One 14 pins header position auxiliary header positions
• One two pins debug position for UART TX from ESP32's
• One two pins reset position for TinyPico ESP32.

The schematic The schematic shows the power and signals which are connected. The routed GPIO are the ones required for SPI and I2C buses. Most signals are not connected at all.

Solder a female header to the ESP development module, and you have access to other signals. Eliminate the breadboard bus rats net with this adapter board!

Often the I2C breakout board has the pull-up resistors added, so no additional resistors are added to the board.

Display

The 2.8” 280x320 TFT SPI color display (SKU: MSP2807) is popular and easy to find online. Note that the adapter board does not connect the touch functionality (but is available in the header) for the display. The wires for the display SD card port are not connected.

Fabrication specification

The board size is 5.4"x6.6" (137.16 x 167.64 mm) and fabricated as a two-layer board.

• board material: FR4
• board thickness: 1.6 mm (63 mils)
• four M3 mounting holes: 3.2mm (1/8")
• header hole diameter: 1 mm (39.4 mils)
• surface finish: HASL (with lead)
• copper layer thickness: 35 um (1.4 mils)
• board color: green
• board text: white
• board weight: 80 grams (2.82 oz)

Open Source

This project is open-source. Find all KiCad PCB design and fabrication files for this board in the documentation. I love designing, making, and releasing my projects as open source. I do it because I believe it's important to share knowledge and give back to the community, as many have done before us. It helps us all learn and grow.

Note: Female headers are not included in the offer.