***Question***
How can PicoW read MEMS digital microphone output?
---
***Answer***
*Update 2023jan11hkt2236*
*0.9 Si5351 testing notes*
I found Si5351 very flexible and easy to use. So I have begun reading the datasheet and trying to write a simple PicoW micropython python to test it.
[![si5351 01][1]][1]
(1) [I2C Programmable Any Frequency CMOS Clock Generator + VCXO Datasheet - Silicon Labs][2]
(2) [Programming si5351 with the PyBoard (micropython) YouTube Tutorial][3]
---
*0.8 1MHz to 3.5MHz Clock for MT40DT01*
The 1MHz Clock works for MT40DT01. However it is expensive and awkward to handle. So I am looking for an alternative. The following looks good.
[5351 Si5351A High Frequency Square Wave Signal Generator - AliExpress HKD21][4]
---
*0.7 MT40DT01 now with external 1 MHz clock outputs something*
[![mic test 0901][5]][5]
[![mic test 02][6]][6]
[![mic test 0903][7]][7]
---
*0.6 Microphone not working because input frequency to low, < 1MHz*
Earlier I used 200kHz as clock frequency but found nothing happening. I checked the datasheet and found that the minimum frequency is 1 MHz (Max 3.5MHz). Now I have a problem, because it seems that the PicoW's system timers are software timers and so could not support too many clocks at high frequency higher than 500 KHz. So ***now I need to check if an external clock > 1MHz can solve the problem***.
---
*0.5 Real time test setup*
mt40dt01 test program listing - https://penzu.com/p/2f213cb6
[![realtime test 01][8]][8]
---
*0.4 Creating 4 PicoW system clocks, two for real time tone signals, two for MT34DT01 MEMS digital microphone clock inputs*
[![mt34dt01 test 1][9]][9]
[![mt34dt01 test 2][10]][10]
[![mt34dt01 test 3][11]][11]
---
[PicoW Mems Digi Mic v13.0 Program Listing][12]
# PicoW Mems Digi Mic v16.0 - tlfong01 2023jan07hkt2138
import machine
import utime
from machine import Pin, Timer, RTC
print('MemsDigiMicV16.0, 2023jan07hkt2138')
redFreq = 20000 # DigiMic #1 Clock signal
grnFreq = 4 # For troubleshooting
redLed = Pin(0, Pin.OUT, value = 1) # Create Red LED object, init On
grnLed = Pin(1, Pin.OUT, value = 1) # Create grn LED object, init On
redTimer = Timer() # Red LED timer, callback toggleRedLed
grnTimer = Timer() # Grn LED timer, callback toggleGrnLed
def toggleRedLed(dummy): #ISR RedLed
redLed.toggle()
return
def togglegrnLed(dummy): #ISR grnLed
grnLed.toggle()
return
redTimer.init(freq = redFreq, mode = Timer.PERIODIC, callback = toggleRedLed)
grnTimer.init(freq = grnFreq, mode = Timer.PERIODIC, callback = togglegrnLed)
utime.sleep(10)
redTimer.deinit()
grnTimer.deinit()
redLed.off()
grnLed.off()
# *** End of program ***
---
*0.3 Using MT34DT01 MEMS Digital Microphone for Very simple Speech Recognition*
The MP34DT01-M MEMS digital microphone datashheet says it can be used for AI applications such as speech recognition, (Ref 1). Now I am thinking of exploring the fisibility of doing very simple speech recognition, say, for a very, very small subset of audio signals, denoting doggie commands like "Sit", "Eat", "OK" etc.
I read that it is practical to use Rpi python to do Alphabet reqognition of 26 handwritten patterns A to Z, using CNN (Convolutional Neural Network), for example, Glezer, Ref 2. In CNN application usually represent one visual paatern, say one alphabet, by a liner list of bits. For audio patterns, I think we can also similarly represent doggie commends "Sit", "Eat" etc, each by a list of bits.
The MEMS digital microphone MP34DT01 seems ideal for our simple application. This is what will explored in the subsquent sections.
(1) [MP34DT01-M MEMS audio sensor omnidirectional digital microphone - STM 2014][13]
(2) [Running a Convolutional Neural Network on Raspberry PI - Marcelo Glezer, 2020oct01][14]
---
*0.2 Tone Generator and Frequency Counter Schematic*
[![tone gen and freq ctr][15]][15]
---
*0.1 MEMS PDM Digital Microphone MT34DT01 Test Setup V0.1*
[![mt34dt01 v0.2][16]][16]
---
*1. Introduction.*
We can connect the MEMS microphone output pin to a PicoW GPIO pin and read signal, into a list for later processing.
---
*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.
---
*3. Trying Blink rates 1kHz, 2kHx, to simulate 1kHz, 2kHz tones*
[![1k, 1k led blinking tones][17]][17]
[![1k, 2k tones 2][18]][18]
---
*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][19]][19]
---
*5. MP34DT01-M MEMS audio sensor omnidirectional digital microphone*
(5.1) [MP34DT01-M MEMS audio sensor omnidirectional digital microphone][20] - ST
(5.2) [PDM Microphont: PDM Signal Definition - ST Video][21]
[![pdm interface][22]][22]
---
*6. MT34DT01 MEMS Digital Microphone*
[![mt34dt01 mems digi mic][23]][23]
---
*9. / to continue, ...*
---
***References***
(1) [Adafruit PDM Microphone Breakout 1][24]
(2) [Adafruit PDM Microphone Breakout 2][25]
(3) [AliExpress Digital MP34DT01 Microphone Module Simple Pulse Density Modulation Output PDM Digital MEMS Microphone Module - HK$27][26]
(4) [TaoBao MP34DT01 MEMS PDM Microphone - ¥25][27]
(5) [1000 Hz Test Tone - Sonic Electronix][28]
(6) [Using a Digital Microphone (MT34DT01) on STM32 - Dario Petrillo, Hackster, 2022jul14][29]
---
***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 ***
---
*Appendix B - Blinking LEDs Video*
[PicoW blinking two LEDS][30]
---
*Appendix C - MEMS Mic, PicoW GPIO Eval Brd Setup*
[![gpio eval brd][31]][31]
# 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/NQXdl.jpg
[2]: https://www.digikey.com.mx/htmldatasheets/production/1763475/0/0/1/Si5351A-B-C-Datasheet.pdf
[3]: https://www.youtube.com/watch?v=2cb1LLoeT-Y
[4]: https://fr.aliexpress.com/item/33050185099.html?gatewayAdapt=glo2fra
[5]: https://i.sstatic.net/zRyPF.jpg
[6]: https://i.sstatic.net/J6qmC.jpg
[7]: https://i.sstatic.net/DhW6k.jpg
[8]: https://i.sstatic.net/7nZFr.jpg
[9]: https://i.sstatic.net/NB6TH.jpg
[10]: https://i.sstatic.net/Ci0t7.jpg
[11]: https://i.sstatic.net/AzHQX.jpg
[12]: https://penzu.com/p/363b494f
[13]: https://datasheet.octopart.com/MP34DT01-M-STMicroelectronics-datasheet-41169337.pdf
[14]: https://medium.com/swlh/running-a-convolutional-neural-network-on-raspberry-pi-4fc5bd80aa4d
[15]: https://i.sstatic.net/MS0Jz.jpg
[16]: https://i.sstatic.net/Di2xI.jpg
[17]: https://i.sstatic.net/mofeV.jpg
[18]: https://i.sstatic.net/W1qsp.jpg
[19]: https://i.sstatic.net/otxJZ.jpg
[20]: https://www.mouser.com/datasheet/2/389/mp34dt01-m-955068.pdf
[21]: http://st-videos.s3.amazonaws.com/STM32_Microphone_Audio_Acquisition_Part2_PDM_Microphone.mp4
[22]: https://i.sstatic.net/fTW7z.jpg
[23]: https://i.sstatic.net/5rfv8.jpg
[24]: https://www.adafruit.com/product/4346
[25]: https://www.adafruit.com/product/2716?gclid=Cj0KCQiAtbqdBhDvARIsAGYnXBMlWo5Px8MPOsGz6mfOlcQTx8zKgi5kgOL-PCL5XbvoMZWBFNUa23UaAjYmEALw_wcB
[26]: 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
[27]: https://item.taobao.com/item.htm?_u=13thdsb1b52&id=626041686368
[28]: https://www.youtube.com/watch?v=TbPh0pmNjo8
[29]: https://www.hackster.io/dario_petrillo/using-a-digital-microphone-on-stm32-riot-os-1a3f44
[30]: https://youtu.be/SlbA8wIEvJY
[31]: https://i.sstatic.net/GKznZ.jpg