Forrest O. Fab Academy

Week 09. Input Devices

Adafruit LSM303AGR

The board that I produced last week wasn't up to the task, so I fell back to bread board.

RP2040 on breadboard with I2C

Connecting LSM303AGR to XIAO RP2040 with JST to pin connector.

Note the QUIIC connector color convention for the wires.

  • Yellow: SDL
  • Blue: SDA
  • Red: 3.3V
  • Black: ground

QUIIC pinout graphic. XIAO RP2040 pinout graphic.

Saleae probing between I2C connection between magnetometer and microcontroller.

Probing the I2C connection with the Saleae. I followed the color convention for blue and yellow wires.

Update with own board

Once I had my own circuit board working after week 10 I repeated the exercise, and got the same result.

Using the magsensor.ino example code, which reads the magnetometer sensor every 100ms. It is loaded on the XIAO RP2040.

Seleae screenshot, zoomed to 2 seconds.

2s view. You can see the 10 times per second that data is communicated.

Saleae screenshot, zoomed to 1ms.

1ms view. Zooming into 1 report of the sensor reading.

X: -55.35  Y: -30.60  Z: -30.75  uT
X: -54.60  Y: -30.60  Z: -30.75  uT
X: -55.50  Y: -30.15  Z: -31.20  uT

This program outputs messages like this in the Arduino serial monitor.

Next steps

  • Characterize power requirements and SPI control of addressable LED strip.
    • FastLED Arduino library.
    • WLED ESP32 web server for LED control.
  • Make circuit board that can support battery, RP2040, sensor, and LED power and control.
  • Connect mag sensor and do programming to make LED colors react to orientation changes.
  • Continue tactile labyrinth prototyping.

Reference