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ESP32S2 Mini Multi PCB
Several products of ESP32 equipped with SSD1306 are available.
However, I have never seen a product equipped with an SSD1306 with an SPI interface.
Also, I have never seen a product equipped with a 1.3 inch SSD1306 product.
Therefore, I designed a PCB that can be equipped with an SPI interface and 1.3 inch products.
I use ESP32S2-Mini Development board.
Although this product is very small, it is equipped with 2MB of PSRAM.
You can download the Garbers file from here.
You can use the zip file to order it yourself from PCB manufacturing vendors such as Elecrow/FusionPCB/PCBWay.
I ordered it on 3/31 and it arrived on 4/9.
You can repeat my order from here.
Configuration
for SPI interface
for I2C interface
Why ESP32S2 Mini?
Cheap!!
Only $1.49 excluding shipping.
I bought two and it cost $4.27 including shipping.
About ESP32S2 Mini
A Type-C USB connector is mounted on the board, but a USB-TTL conversion chip is not mounted.
The circuit diagram is available here.
USB ports D- and D+ are connected to GPIO19/20.
Since it uses the chip's USB-OTG function, it will not be recognized as a USB device even if you simply connect it to the host with a USB cable.
To write firmware, press ButtonRST while pressing Button0, then release ButtonRST and then Button0.
Now the device will enter DFU mode, the USB device (/dev/ttyACM0) will appear, and you can upload the firmware.
Once the firmware upload is complete, press ButtonRST again.
The firmware will now start.
If you press ButtonRST without pressing Button0, the USB device will disappear.
In other words, USB can be used for writing, but not for STDOUT.
This board is not suitable for debugging.
On ESP32-S2, GPIO43/44 are U0TXD/U0RXD, but this GPIO is not present on the pin header.
This board has 4MB of FLASH and 2MB of PSRAM.
It's strange that it is recognized as having an external flash.
There is no external flash anywhere on the board.
Enable PSRAM
ESP32S2's RAM is very small.
You can avoid running out of memory by enabling PSRAM.
In order to use PSRAM, you need to enable PSRAM by following the steps below.
Please note that this procedure is for ESP-IDF V5.2 and may change in the future.