Has PDM microphone been attempted with an esp32-c3?

[UsableLoki8221]

I am wondering if any software hack has been tried in order to expand microphone functionality to PDM since all the i2s mics on the market are pretty much obsolete.

[DedeHai]

Might be doable but could also put too much strain on limited cpu power.
Analog mic support is in PR already, that would also be a viable option.

[UsableLoki8221]

Oh sweet, thanks for letting me know. I ordered a PDM breakout so I'll see if I can manage anything usable out of it

[softhack007]

@DedeHai @UsableLoki8221 PDM is basically just a cheap version of I2S. Maybe we should look into supporting TDM instead.

🤔 the latest -C3 reference manual says that PDM RX (i.e. PDM receiving) is supported by the hardware, so we might have a chance for PDM support, at least with V5 builds. It's a bit unexpected though, because I am very sure that espressif has stated "no PDM on the -C3" a few years ago.

https://documentation.espressif.com/[esp32-c3_technical_reference_manual_en.pdf](https://documentation.espressif.com/esp32-c3_technical_reference_manual_en.pdf#i2s)#i2s

Normal PDM RX mode
In this mode, pulse density modulation (PDM) data is received and stored into memory via DMA. Used signals: WS and DATA. PDM standard is supported in this mode by user configuration.

[DedeHai]

C3 has no PDM hardware, but can still receive it, needs to be software decoded at about 160kb/s so could eat quite some cpu time
Edit: this number is based on a 1.3MHz PDM clock.

[UsableLoki8221]

Would be super to have the capability since i2s is practically non-existent except for legacy dev breakouts and AR recommends against analog mics.

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On Fri, Aug 14, 2026, 9:29 AM Damian Schneider ***@***.***> wrote: *DedeHai* left a comment (wled/WLED#5799) <#5799 (comment)> C3 has no PDM hardware, but can still receive it, needs to be software decoded at about 160kb/s so could eat quite some cpu time — Reply to this email directly, view it on GitHub <#5799?email_source=notifications&email_token=BJ6AZMFRLISUOCKR4XXEEVL5J4H4JA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMRZGM4DKNBZGYZKM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5293854962>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BJ6AZMH7JXP2YE73YDVB4CL5J4H4JAVCNFSNUABEKJSXA33TNF2G64TZHM3TMOJZGAZDAOJ3JFZXG5LFHM2TCNBYGAZTCNZWGSQXMAQ> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/BJ6AZMAAAEGE6ZYOE4ATI535J4H4JA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMRZGM4DKNBZGYZKM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/BJ6AZMAHMTJPH6FURJZTYB35J4H4JA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMRZGM4DKNBZGYZKM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>

[softhack007]

@UsableLoki8221 no need to panic. I2S is definitely not dead, and PDM is definitely not the answer - PDM microphones are low quality when compared to I2S mics.

While a few of the recommended models - especially INMP441 - are not in production from the original vendor any more, you can still get them as "China clones" everywhere. Millions of makers around the world are still happily using INMP441 clones.

Basically you can use any microphone chip with an I2S interface - research for parts with I2S support and you'll find them.

I think that Adafruit has some ready-made breakouts with I2S interface.

[UsableLoki8221]

@softhack007 I appreciate the responses and thought towards this topic. The issue is toward PCB assembly for the bare component itself regarding any sizable production. I have no idea how the tons of listings for INMP441 get their stock for those breakouts when there are 0 stock in mouser or LCSC catalogs for tape and reel. The only i2s mics appearing in stock are the T5837, ICS-43434/43432 and they're very costly each ($3-5) compared to the copious number of PDM found at <1$. Considering that AR effects don't need high fidelity microphone responses its very appealing to consider PDM as an option if possible. Even if the PDM processing is taxing on cycles someone in user mod territory could digest a warning for software limitations. My use case is simply for a linear count of 21 pixels so I'm hoping once I got time to mess with the PDM breakout I ordered I can report back

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On Sun, Aug 16, 2026, 7:12 AM Frank Möhle ***@***.***> wrote: *softhack007* left a comment (wled/WLED#5799) <#5799 (comment)> @UsableLoki8221 <https://github.com/UsableLoki8221> no need to panic. I2S is definitely not dead, and PDM is definitely not the answer - PDM microphones are low quality when compared to I2S mics. While a few of the recommended models - especially INMP441 - are not in production from the original vendor any more, you can still get them as "China clones" everywhere. Millions of makers around the world are still happily using INMP441 clones. Basically you can use any microphone with an I2S interface. Just research for parts with I2S support. I think that Adafruit has some ready-made breakouts with I2S interface. — Reply to this email directly, view it on GitHub <#5799?email_source=notifications&email_token=BJ6AZMFO43UNE27QRYU5TID5KGJKTA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZQG4YTINZYGA32M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5307147807>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BJ6AZMEPCBRKG7Y2OX44IBT5KGJKTAVCNFSNUABEKJSXA33TNF2G64TZHM3TMOJZGAZDAOJ3JFZXG5LFHM2TCNBYGAZTCNZWGSQXMAQ> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/BJ6AZMEIX5RX3EOZGLPXJAL5KGJKTA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZQG4YTINZYGA32M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/BJ6AZMHROTEXTF2GZJUNRPD5KGJKTA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZQG4YTINZYGA32M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>

[DedeHai]

I ran a quick test with an arduino sketch and PDM looks feasible. It will eat quite some RAM (like 4-5k for buffers and LUT) and use ~5% of CPU time - roughly the same amount that FFT calculations take so it should not significantly impact the FPS.
If price is the issue and quality is not - just go analog, those can be had for 0.5$

[UsableLoki8221]

Cool news! Yeah I was eventually going to try between both but all the bias against recommending analog made me curious toward PDM alternative. Does analog work on esp32-c3 v16.0.1 or is that just with the latest update you made to the API?

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On Mon, Aug 17, 2026, 7:35 AM Damian Schneider ***@***.***> wrote: *DedeHai* left a comment (wled/WLED#5799) <#5799 (comment)> I ran a quick test with an arduino sketch and PDM looks feasible. It will eat quite some RAM (like 4-5k for buffers and LUT) and use ~5% of CPU time - roughly the same amount that FFT calculations take so it should not significantly impact the FPS. If price is the issue and quality is not - just go analog, those can be had for 0.5$ — Reply to this email directly, view it on GitHub <#5799?email_source=notifications&email_token=BJ6AZMBYFMGR3KUM5MDFHBT5KLUW5A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZRGU2DSNRTGIY2M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5315496321>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BJ6AZMF3EYYIPRCDAUKXR335KLUW5AVCNFSNUABEKJSXA33TNF2G64TZHM3TMOJZGAZDAOJ3JFZXG5LFHM2TCNBYGAZTCNZWGSQXMAQ> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/BJ6AZMENLICRMZX4IM3TPW35KLUW5A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZRGU2DSNRTGIY2M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/BJ6AZMC5JYSFZW2IU3NZDVL5KLUW5A5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZRGU2DSNRTGIY2M4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>

[DedeHai]

difference between analog an PDM is mostly immunity to HF noise - if you do not screw up your design they should perform very similar.
I added analog in a long time ago but it was never merged. Now with IDF V5 it has better support so I added it again. Its in PR.

[UsableLoki8221]

Would you mind pointing to the relevant PR? Thank you btw

…

On Mon, Aug 17, 2026, 7:52 AM Damian Schneider ***@***.***> wrote: *DedeHai* left a comment (wled/WLED#5799) <#5799 (comment)> difference between analog an PDM is mostly immunity to HF noise - if you do not screw up your design they should perform very similar. I added analog in a long time ago but it was never merged. Now with IDF V5 it has better support so I added it again. Its in PR. — Reply to this email directly, view it on GitHub <#5799?email_source=notifications&email_token=BJ6AZMD6YWG52HY5QIRQUCT5KLWWJA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZRGU3DKNRXGA4KM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-5315656708>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BJ6AZMGBQVCLNI6LVZLEJ2T5KLWWJAVCNFSNUABEKJSXA33TNF2G64TZHM3TMOJZGAZDAOJ3JFZXG5LFHM2TCNBYGAZTCNZWGSQXMAQ> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/BJ6AZMHYNFBH6PLQDCX3BKD5KLWWJA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZRGU3DKNRXGA4KM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/BJ6AZMFH5HYMSW4WMFOTN7D5KLWWJA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTKMZRGU3DKNRXGA4KM4TFMFZW63VHNVSW45DJN5XKKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>

[DedeHai]

#5764 #5773

[DedeHai]

@UsableLoki8221 I actually got this to work, still a proof of concept but could eventually make it into AR.
code for that is here https://github.com/DedeHai/WLED/tree/AR_V5_C3_PDM_support