Is there support for PDM I2S microphones?

[rmick]

I am using the M5stack-Core 2 module, which includes almost everything you could desire, including an I2S mic and I2S speaker. The only problem is that this mic works in PDM I2S mode and I can't see anyway to configure this option in the library.

I believe that the Espressif framework supports this functionality, so is it possible to add it as an option in your amazing library?

[pschatzmann]

Oh, I didn't know that this exists. I just committed a change to my project.
In the I2S Config you can set now signal_type=PDM.
Please let me know if this works...

[rmick]

Thanks, that is awesome. :-)

[rmick]

Not sure if it works, because there are a couple of compilation error in other modules.

Arduino/libraries/arduino-audio-tools/src/AudioHttp/HttpRequest.h: In member function 'virtual int audio_tools::HttpRequest::connect(const char*, uint16_t, int32_t)':
Arduino/libraries/arduino-audio-tools/src/AudioTools/AudioLogger.h:129:135: error: format '%s' expects argument of type 'char*', but argument 4 has type 'int' [-Werror=format=]
#define LOG_OUT(level, ...) snprintf(AudioLogger::instance().prefix(FILE,LINE, level).str(),LOG_PRINTF_BUFFER_SIZE,VA_ARGS); AudioLogger::instance().println();
^
Arduino/libraries/arduino-audio-tools/src/AudioTools/AudioLogger.h:132:77: note: in expansion of macro 'LOG_OUT'
#define LOGI(...) if (AudioLogger::instance().level()<=AudioLogger::Info) { LOG_OUT(AudioLogger::Info, VA_ARGS);}
^
Arduino/libraries/arduino-audio-tools/src/AudioHttp/HttpRequest.h:173:13: note: in expansion of macro 'LOGI'
LOGI("connected %s timeout %d", is_connected, timeout);

[pschatzmann]

Strange, I can't reproduce your errors.

• Is this in Arduino or PlatformIO ?
• What ESP32 Arduino Version are you using
• What Sketch are you compiling
• In Arduino Settings Compiler Warnings: do you have the setting Default ?

[rmick]

Answers below From: Phil Schatzmann ***@***.***> Sent: Thursday, 12 May 2022 6:56 PM To: pschatzmann/arduino-audio-tools ***@***.***> Cc: Richie Mickan ***@***.***>; Author ***@***.***> Subject: Re: [pschatzmann/arduino-audio-tools] Is there support for PDM I2S microphones? (Discussion #203) Strange, I can't reproduce your errors. * Is this in Arduino or PlatformIO Arduino 2.0 * What ESP32 Arduino Version are you using M5stack-Core2 * What Sketch are you compiling ESP32_stream-i2s-webserver_wav.ino * In Arduino Settings Compiler Warnings: you you have the setting Default ? Set to ALL. I was always taught that you want to see all warnings, as they are there for good reason and so you can fix them before they bite you 😉 All resolved by changing the warnings back to default. Thank you. P.S. I have never seen warnings cause a ‘Compilation Error: exit status 1’ message before. Then I just noticed a little line above that states cc1plus: some warnings being treated as errors Grhhhh! I learnt something new today. Interestingly it all worked perfectly yesterday before I pulled your latest update from github, despite warnings being set to all - but maybe my last pull was a few months ago.

[rmick]

All working perfectly.

Here are the config settings for anyone who wants to try the microphone in the M5Stack-Core2 unit.

auto config = i2sStream.defaultConfig(RX_MODE);
config.signal_type = PDM;
config.i2s_format = I2S_STD_FORMAT;
config.sample_rate = 22050;
config.channels = 2;
config.bits_per_sample = 16;
config.pin_bck = 12;
config.pin_data = 34;
config.pin_ws = 0;

[pschatzmann]

I updated the documentation and added a section for PDM microphones: https://github.com/pschatzmann/arduino-audio-tools/wiki/External-ADC