Face-Following Eyeball using a Raspberry Pi Pico, a Person Sensor, and an ST7789 display, controlled using CircuitPython. Based on original code by @todbot / Tod Kurt, at github.com/todbot/circuitpython-tricks/blob/main/larger-tricks/eyeballs/.
The Person Sensor from Useful Sensors is a small, low-cost hardware module that detects nearby peoples’ faces, and returns information about how many there are, where they are relative to the device, and performs facial recognition. It is designed to be used as an input to a larger system, and this example shows how to use it to a small display that draws an eyeball that follows the nearest face.
To build this project you'll need:
- Raspberry Pi Pico H.
- Person Sensor from Useful Sensors.
- Qwiic connector cable with female jumpers.
- 8 Female to female jumper wires.
- Adafruit 1.54" 240x240 TFT LCD Display
The only soldering needed is to attach the headers to the LCD display. You should be able to use other displays supported by CircuitPython, but you'll need to figure out the pins. Other ST7789-based displays will be easiest. You can also use a regular Pico and solder on the headers yourself if you don't have a Pico H.
- Solder on the header to the display.
- Wire the display pins to the corresponding Pico pins.
| Pico Pin | Display Pin |
|---|---|
| Pin 21 (GP16, SPI0RX) (Yellow) | MISO> / SO |
| Pin 22 (GP17, SPI0CSn) (Green) | TFTCS / TC |
| Pin 23 (GND) (Brown) | Gnd / G |
| Pin 24 (GP18, SPI0SCK) (Orange) | SCK< / CK |
| Pin 25 (GP19. SPI0TX) (Blue) | MOSI< / SI |
| Pin 26 (GP20) (Black) | RST / RT |
| Pin 27 (GP21) (White) | DC / DC |
| Pin 39 (VSYS) (Red) | Vin / V+ |
The colors are those used on the wiring diagram below. There are two different abbreviations for pins on the display, on the front and the back of the board, so I've included both in the description.
Wiring up the sensor requires 4 jumpers, to connect VDD, GND, SDA and SCL. We're using I2C port 0, which on the Pico is assigned to GPIO4 (SDA, pin 6) and GPIO5 (SCL, pin 7) in software. Power is supplied from 3V3(OUT) (pin 36), with ground attached to GND (pin 38). If you're using Qwiic connectors, the colors will be black for GND, red for 3.3V, blue for SDA, and yellow for SDC. It's the same setup as the introductory CircuitPython sample code.
You'll need the display and sensor both facing in the same direction, with the I2C connector of the sensor at the top, and the display's pins at the bottom, so they're in the right orientation.
You should read the official guide to setting up CircuitPython on a Pico for the latest information, but here is a summary:
- Download CircuitPython for your board from circuitpython.org. The Pico
version is available at https://circuitpython.org/board/raspberry_pi_pico/.
This project has been tested using the
8.0.0-beta.2version. - Hold down the
bootselbutton on the Pico and plug it into a USB port. - Drag the CircuitPython uf2 file onto the
RPI-RP2drive that appears.
Once you've followed those steps, you should see a new CIRCUITPY drive appear.
You can now drag code.py files onto that drive and the Pico should run them.
We need the adafruit_imageload and adafruit_st7789 libraries to draw the eyeball, so the first step is to download a big bundle of all the CircuitPython libraries from circuitpython.org/libraries. You'll need to find the right bundle for your CircuitPython version.
Once you have that downloaded, unpack the bundle on your local machine. In the
file viewer, go to the lib folder within the unpacked bundle and copy the
adafruit_imageload directory and the adafruit_st7789.mpy file into the lib
folder on the CIRCUITPYTHON drive.
Now your eyeball is set up, copy the code.py, eye0_ball2.bmp, and
eye0_iris0.bmp files from this repository into the CIRCUITPYTHON drive. You
should notice that the green LED on the Person Sensor lights up when it sees
your face, and see an eyeball that moves as you move you face within view of the
sensor.
There's probably enough SPI pins to run two eyeballs from the Pico, if you want a pair?