Testing the board with a M5Stack

What is the M5Stack ?

That's an ESP32, with a screen of 320x240.

For a 120us acquisition, that leaves 3us per pixel.. Still interesting to see. Moreover, there seems to be a 512KB RAM, would be enough to store long acquisitions. One line is 256kB at 64Msps.

Even a FFT processing would be possible.

Connectors necessary were :

  • 5V
  • GND
  • CS
  • MISO
  • MOSI

Actual connections:

  • M5STACK pin22 -> RPi header GPIO 23 (Ice40 reset)
  • M5STACK pin21 -> RPi header GPIO 8 (Ice40 CS)
  • M5STACK pin19 -> RPi header GPIO 10 (Rpi MISO)
  • M5STACK pin23 -> RPi header GPIO 9 (Rpi MOSI)
  • M5STACK pin18 -> RPi header GPIO 11 (Rpi CLK)
  • M5STACK GND to RaspberryPi header GND pin
  • M5STACK 5V -> RaspberryPi header 5V pin

Some code

Only SPI libs and M5Stack were necessary.. and a proof of concept was done with a single line acquisition process, for 200us, with a low gain.

File source is available

Results

With the calibration rig

With a piezo in a mug

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