The ESP32 firmware acts as a WiFi interface the STM32 module. It gets binary data through the I2C connection with the ESP32 and uploads it to a configured web address. The binary response is then passed back to the STM32 for decoding. The ESP32 handles only the WiFi interface. It is up to the STM32 to check all errors relating to decoding binary data.

Flashing

‍Before running the following ensure you have updated the ports in platformio.ini described in the root README.md.

The esp32 is programmed through a bootloader through UART. A USB to TTL convert is required to program the microcontroller with your computer and can be found cheaply online. Ensure it supports 3.3V logic levels. Connect TX to RX and RX to TX, RTS, CTS, and GND. We recommend not connecting Vcc as it is already powered through the USB connection. More recent versions of the board have the header removed.

VSCode

Check the correct environment is selected. Should be env:esp32 (esp32)

VSCode env

‍NOTE: If the filesystem needs to updated you will need to run Upload File System image before Upload and Monitor. THe filesystem store html webpages for the configuration portal.

Goto PlatformIO Tab -> Project Tasks -> Upload and Monitor

VSCode Upload and Monitor

CLI

The following can be used to flash the firmware on the esp32

‍NOTE: These must be separate commands or else the firmmware will not be updated.

pio run -e release -t uploadfs

pio run -e release -t upload -t monitor

‍Note: If you do not have RTS and CTS connected, you will need to load into the bootloader mode. This can be done by holding the BOOT button while pressing the RESET button for the esp32. The buttons are located right above the esp32 module.

Testing

We have included the python script tools/http_server.py to enable testing the WiFi interface of the ESP32. By default the server simulates a success POST request, returning a 200 response. The flag --error allows for a 418 to test error handling. See http_server.py --help for more usage information. We recommend hosting a WiFi network for the ESP32 on your local machine. An alternative is having your local machine and ESP32 connected to the same WiFi network. The following are instructions for testing the firmware on the ESP32:

Configure local WiFi network (Optional) If you are using a shared WiFi network, skip this step and set ssid and pass in the ESP32 firmware to the shared WiFi network.

Unix

Create the hotspot using NetworkManager. Replace ifname with the name of your wireless interface.

nmcli dev wifi hotspot con-name spstesting ifname [ifname] ssid spstesting password "test1234"

To stop the hotspot.

nmcli connection down spstesting

To reactivate the hotspot.

nmcli connection up spstesting

To delete the connection.

nmcli connection delete spstesting

macOS

TODO

Windows

TODO

Start HTTP server. By default the server listens on all interface on port 8080.

python http_server.py

Update connection parameters for the WiFi network and server address. The WiFi network should be the same network that your device connected to. Replace [your ip address] with the IP address of your local machine. By default the port is 8080.

 ++
const char ssid[] = "spstesting";
const char pass[] = "test1234";
 
Dirtviz api("[your ip address]", 8080);

Flash the ESP32. Use the following command to select the correct environment for example_dirtviz.cpp. See Flashing for more information.

pio run -e example_dirtviz -t upload

Monitor the server terminal and serial output to ensure data is being properly sent.