# Microcontroller

Microcontroller are small computers on an integrated circuit.
It contains a processor, memory and programmable in- and output.

## ESP32

The ESP32 is a cheap and low-energy microcontroller made by Espressif Systems.
It features Wi-Fi and [Bluetooth](/wiki/bluetooth.md).
Some variants of this chip also include LoRa-capability and can be used to communicate via
[Meshtastic](/wiki/meshtastic.md).

### Usage 

The following sections address various usages and setups of the ESP32.

### Setup in Arduino IDE

For the ESP32 to work correctly in the Arduino IDE some things have to be set up.
This section addresses the steps to take to use the ESP32 with the Arduino IDE.

Under preferences set the following URL under `Additional boards manager URLs`.

`https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json`

Afterwards install the board manager `esp32`.

### Flash Firmware on the ESP32 

This section especially focusses on the ESP32S3 microcontroller.
Make sure that the ESP32 is in [programming mode](#programming-mode).
For other microcontroller of the ESP32-xx family the process should be similar.
This following guide is written for [Windows](/wiki/windows.md).

- Download [ESP RF Test Tool and Test Guide](https://www.espressif.com/en/support/download/other-tools)
- Download [Firmware of ESP32S3](https://files.seeedstudio.com/wiki/SeeedStudio-XIAO-ESP32S3/res/XIAO-ESP32S3-firmware-20240814.zip)
- Open `EspRFTestTool_vX.X_Manual.exe`
  - Select the `ESP32S3` as `ChipType`
  - Select the correct `COM` for your ESP
  - Set the `BaudRate` to 115200
  - Click `open`
  - Click `Select Bin` and search for your ESP32S3 Firmware (probably named `xiao_esp32s3_firmware.bin` or similar)
  - Left of the `Select Bin` button select `USB` and `Flash` for the two drop-down options
  - Click `Load Bin`
  - After the upload of the data a completion message should appear
- The ESP32S3 is completely flashed

### Programming Mode  

When connecting an ESP32 to the computer it needs to be in programming mode.
If it is not in programming mode it will show up as port but will encounter `Write Timeout` Errors
when trying to flash programs or firmware onto it.
To put the ESP32 in the programming mode press and hold the Boot-Button (usually labeled `B`).
Then press and release the Reset-Button (usually labeled `R`).
Afterwards release the Boot-Button.
The board now should be in programming mode and it should be possible to upload and flash programs
or firmware onto it.
This section is based on a Reddit
[comment by cmatkin](https://www.reddit.com/r/esp32/comments/1g8gerg/getting_a_write_timeout_error_on_my_esp32s3/).

### Troubleshooting 

The following sections address various errors that can occur when using the ESP32. 

#### Can Not Access the Microcontroller Under Linux 

Sometimes the rights to access the ESP32 are set wrong.
To fix this run the following command. 

```sh 
sudo chmod 777 /dev/ttyACM0
```