Signal/Colour Generator

sensors_feather-m4-express-colour-and-signal-generator.jpg
Feather M4 Express used as signal generator and colour source for demonstrating sensor plotter on CLUE.

A Feather M4 Express board was enlisted to aid the demonstration of the sensor plotter in the video on the previous page. It provided:

  • alternating red, green blue light from the onboard NeoPixel for the CLUE's APDS-9960 colour sensor;
  • two analogue signals from A0 and A1 which were connected to the #0 and #1 pads on the CLUE using some test hooks.

Its SAMD51 (M4) processor is useful here as it has 2 DACs.

The code running on the board was very short and simply typed in over the serial console on CircuitPython's REPL.

Download: file
import audioio, board, neopixel, time

dacpair = audioio.AudioOut(board.A0,
                           right_channel=board.A1)
filename = "adafruit-spinning-logo-plot-2chan.wav"
wav_file = open(filename, "rb")
samples = audioio.WaveFile(wav_file)
samples.sample_rate = 500
dacpair.play(samples, loop=True)
pixel = neopixel.NeoPixel(board.NEOPIXEL, 1)

# Loop forever showing r, g, b while the
# DACs continue to loop the samples from wav file
while True:
    pixel[0] = (255, 0, 0)  # red
    time.sleep(0.5)
    pixel[0] = (0, 255, 0)  # green
    time.sleep(0.5)
    pixel[0] = (0, 0, 255)  # blue
    time.sleep(0.5)

Wav files are typically used for audio but they can be used for any signal. In this case the adafruit-spinning-logo-plot-2chan.wav has two signals following the top and bottom outline of the Adafruit logo, spinning 1/5th of a revolution in total across five frames.

Adafruit Feather M4 Express - Featuring ATSAMD51

PRODUCT ID: 3857
It's what you've been waiting for, the Feather M4 Express featuring ATSAMD51. This Feather is fast like a swift, smart like an owl, strong like a ox-bird (it's half ox,...
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Basic Multi-Color Micro SMT Test Hooks (6-pack)

PRODUCT ID: 4322
Testing and debugging is a challenging step in board manufacturing. It can be super tricky on a fully populated PCB. So how can you test connections when you have an assortment of...
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This guide was first published on Apr 01, 2020. It was last updated on Apr 01, 2020.
This page (Signal/Colour Generator) was last updated on Aug 06, 2020.