CircuitPython Wi-Fi Server

This section describes how to set up a Wi-Fi server to exchange data with the NML Hand Exoskeleton. The server supports multiple TCP clients and enables real-time communication with a serially connected exoskeleton.

Note

This server is designed for microcontrollers with Wi-Fi support, such as the Raspberry Pi Pico W. It was tested with Adafruit CircuitPython 9.2.4 (2025-01-29) on the Raspberry Pi Pico 2 W (RP2040).

Software Setup

Install CircuitPython on your Raspberry Pi Pico W. Visit the CircuitPython downloads page to download the latest UF2 file. To enter bootloader mode, hold the BOOTSEL button while plugging the board into USB. The board will mount as a USB drive (e.g., RPI-RP2, CIRCUITPY, or BOOT).
Flash the board by dragging and dropping the downloaded .uf2 file onto the mounted drive. The board will automatically reboot into CircuitPython.
Install the required libraries by either copying the lib/ folder to the CIRCUITPY drive or downloading the latest CircuitPython library bundle from the library bundle page. Minimum libraries include:
- adafruit_ticks.py
- simpleio.py
- adafruit_httpserver
- asyncio
- rgbled.py # Custom
- usbserialreader.py # Custom
- webpage.py # Custom

Configure Wi-Fi settings in the settings.toml file at the root of the CIRCUITPY drive:

CIRCUITPYTHON_WIFI_SSID = "your_wifi_ssid"
CIRCUITPYTHON_WIFI_PASSWORD = "your_wifi_password"

(Optional) Set a static IP address by adding the following lines to settings.toml:
```
CIRCUITPYTHON_WIFI_IP = "192.168.1.200"
CIRCUITPYTHON_WIFI_HTTP_PORT = 5000  # Currently hardcoded in the codebase
CIRCUITPYTHON_WIFI_TCP_PORT = 5001
```
Note

If no static IP is specified, the Pico W will attempt to use DHCP. However, a static IP is recommended for stability in multi-client applications.

Hardware Setup

The exoskeleton communicates with the Pico W via UART (or USB). Below are the recommended wiring connections between the Raspberry Pi Pico W and OpenRB-150:

UART Serial Connection:

Pico Pin	OpenRB-150 Pin	Function
GP16	RX	Serial Receive (RX)
GP17	TX	Serial Transmit (TX)
GND	GND	Common Ground
VBUS	V	5V Power Supply

RGB LED Status Indicator:

Pico Pin	LED Pin	Function
GP10	CATH	RGB Common Cathode
GP11	R	Red Channel
GP12	G	Green Channel
GP13	B	Blue Channel

The RGB LED provides server status feedback: - Green: Wi-Fi connected - Red: Disconnected or error - Blue: Client activity (optional)

HTTP Webpage

The server hosts a simple HTTP webpage that allows users to control the exoskeleton and view its status. The webpage is served at the root URL (/) and provides buttons for enabling/disabling motors, toggling LEDs, and viewing the current state of the exoskeleton.