***Question***
How can PicoW read MEMS digital microphone output?
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***Answer***
*Update 2023jan04hkt1638*
*0.1 Tone Generator and Frequency Counter Schematic*
[![tone gen and freq ctr][1]][1]
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*0.2 MEMS PDM Digital Microphone MT34DT01 Test Setup V0.1*
[![mt34dt01 v0.2][2]][2]
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*1. Introduction.*
We can connect the MEMS microphone output pin to a PicoW GPIO pin and read signal, into a list for later processing.
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*2. Simulation*
For prototyping, we can simulate the microphone output signal as a GPIO output pin connected blinking LED, and use another GPIO input pin to read the blinking LED pin.
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*3. Trying Blink rates 1kHz, 2kHx, to simulate 1kHz, 2kHz tones*
[![1k, 1k led blinking tones][3]][3]
[![1k, 2k tones 2][4]][4]
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*4. The OP wishes to connect the MEMS digital mic output to PicoW. So now I am looking at the real thing.
[![ada fruit mems digi mic][5]][5]
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*5. MP34DT01-M MEMS audio sensor omnidirectional digital microphone*
(5.1) [MP34DT01-M MEMS audio sensor omnidirectional digital microphone][6] - ST
(5.2) [PDM Microphont: PDM Signal Definition - ST Video][7]
[![pdm interface][8]][8]
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*6. MT34DT01 MEMS Digital Microphone*
[![mt34dt01 mems digi mic][9]][9]
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*9. / to continue, ...*
---
***References***
(1) [Adafruit PDM Microphone Breakout 1][10]
(2) [Adafruit PDM Microphone Breakout 2][11]
(3) [AliExpress Digital MP34DT01 Microphone Module Simple Pulse Density Modulation Output PDM Digital MEMS Microphone Module - HK$27][12]
(4) [TaoBao MP34DT01 MEMS PDM Microphone - ¥25][13]
(5) [1000 Hz Test Tone - Sonic Electronix][14]
(6) [Using a Digital Microphone (MT34DT01) on STM32 - Dario Petrillo, Hackster, 2022jul14][15]
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***Appendices***
Appendix A - MicroPython program blinking two LEDs simulating two MEMS digital microphone output signals
# Pico W Blink Two LEDs - tlfong01 2023jan01hkt1941
# *** Modules ***
import machine
from machine import Pin, Timer
# *** Configuration***
redLed = Pin(0, Pin.OUT)
greenLed = Pin(1, Pin.OUT)
redFreq = 2
greenFreq = 4
redTimer = Timer()
greenTimer = Timer()
# *** Callbacks ***
def blinkRedLed(dummy):
redLed.toggle()
return
def blinkGreenLed(dummy):
greenLed.toggle()
return
# *** Main ***
redTimer.init(freq = redFreq, mode = Timer.PERIODIC, callback = blinkRedLed)
greenTimer.init(freq = greenFreq, mode = Timer.PERIODIC, callback = blinkGreenLed)
# *** End of program ***
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*Appendix B - Blinking LEDs Video*
[PicoW blinking two LEDS][16]
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*Appendix C - MEMS Mic, PicoW GPIO Eval Brd Setup*
[![gpio eval brd][17]][17]
# PicoW GPIO Input Testing v7.0 - tlfong01 2023jan02hkt1410
# *** 1.0 Modules ***
import machine
import utime
from machine import Pin, Timer
# *** 2.0 Configuration and Functions ***
# 2.1 Blinking LED Configurations and Functions
redFreq = 6 # Red LED blinking frequency
greenFreq = 3 # Green LED blinking frequency
redLed = Pin(0, Pin.OUT, value = 1) # Create Red LED object, init On
greenLed = Pin(1, Pin.OUT, value = 1) # Create Green LED object, init On
redTimer = Timer() # Red LED timer, callback blinkRedLed
greenTimer = Timer() # Greed LED timer, callback blinkGreenLed
# 2.2 Blinking LED Callbacks
def blinkRedLed(dummy):
redLed.toggle()
return
def blinkGreenLed(dummy):
greenLed.toggle()
return
# *** 3.0 GPIO Input Configurations and Functions ***
readGpioPin2 = Pin(2, Pin.IN, Pin.PULL_UP) # Create GPIO input pin object
readGpioPin3 = Pin(3, Pin.IN, Pin.PULL_UP) # Create GPIO input pin object
def readRedLed():
ledStatus = readGpioPin2()
if ledStatus == 1:
return "High"
else:
return "Low"
def readGreenLed():
ledStatus = readGpioPin3()
if ledStatus == 1:
return "High"
else:
return "Low"
def readPrintRedGreenLedStatus():
redLedStatus = readRedLed()
greenLedStatus = readGreenLed()
print('RedLedStatus =', redLedStatus)
print('GreenLedStatus =', greenLedStatus)
return
### *** 4.0 / to continue, ... ***
# *** 9.0 Main ***
# 9.1 Run Red/Green Timer for 2 seconds
redTimer.init(freq = redFreq, mode = Timer.PERIODIC, callback = blinkRedLed)
greenTimer.init(freq = greenFreq, mode = Timer.PERIODIC, callback = blinkGreenLed)
utime.sleep(2)
redTimer.deinit()
greenTimer.deinit()
# 9.2 Set/Read/Print Red/Green LED status
redLed.on()
greenLed.on()
readPrintRedGreenLedStatus()
# *** End of program ***
---
[1]: https://i.sstatic.net/MS0Jz.jpg
[2]: https://i.sstatic.net/Di2xI.jpg
[3]: https://i.sstatic.net/mofeV.jpg
[4]: https://i.sstatic.net/W1qsp.jpg
[5]: https://i.sstatic.net/otxJZ.jpg
[6]: https://www.mouser.com/datasheet/2/389/mp34dt01-m-955068.pdf
[7]: http://st-videos.s3.amazonaws.com/STM32_Microphone_Audio_Acquisition_Part2_PDM_Microphone.mp4
[8]: https://i.sstatic.net/fTW7z.jpg
[9]: https://i.sstatic.net/5rfv8.jpg
[10]: https://www.adafruit.com/product/4346
[11]: https://www.adafruit.com/product/2716?gclid=Cj0KCQiAtbqdBhDvARIsAGYnXBMlWo5Px8MPOsGz6mfOlcQTx8zKgi5kgOL-PCL5XbvoMZWBFNUa23UaAjYmEALw_wcB
[12]: https://www.aliexpress.com/item/4001240664476.html?spm=a2g0o.productlist.main.11.391442abGc1Xty&algo_pvid=6a244fb2-b2ec-4056-9172-b6b7a664e1d8&algo_exp_id=6a244fb2-b2ec-4056-9172-b6b7a664e1d8-5&pdp_ext_f=%7B%22sku_id%22%3A%2210000015426511105%22%7D&pdp_npi=2%40dis%21HKD%2133.27%2126.32%21%21%21%21%21%40212248ba16725455499866162d0736%2110000015426511105%21sea&curPageLogUid=REzyejBWMWnE
[13]: https://item.taobao.com/item.htm?_u=13thdsb1b52&id=626041686368
[14]: https://www.youtube.com/watch?v=TbPh0pmNjo8
[15]: https://www.hackster.io/dario_petrillo/using-a-digital-microphone-on-stm32-riot-os-1a3f44
[16]: https://youtu.be/SlbA8wIEvJY
[17]: https://i.sstatic.net/GKznZ.jpg