How to set ADC sampling rate of ESP32?

[alexretona]

Hello! I'm currently using the ADC analog input of the ESP32 to get sensor readings. However, I'm confused in setting up the sampling rate of the ADC reading. Can I ask for some guide or tips to set the sampling frequency? My goal is to get 6000 samples per second from the ADC input. Thanks!

[ESP_Dazz]

There isn't a hardware mechanism to automatically read N samples per second from the ADC so you'll need to do it by software. I suggest using one of the hardware timer groups to drive an interrupt at 6KHz, then read the ADC in an ISR and put the results into some form of buffer.

[alexretona]

Thank you for this, ESP_Dazz! I will update this post once I am able to do it based on your suggestion.

[ESP_Sprite]

Actually, that's not entirely true. In the current master, the I2S peripheral can be configured to automatically take samples from the ADC and DMA these to memory. See e.g. the i2s_adc_enable function in the i2s driver.

[bobolink]

I wanted to keep costs low by using no external peripherals to the ESP32. Just external analog conditioning components in front of GPIO 34.
I sample at 8ksps, use a software interrupt and two cores. Ping-Pong buffers.
Mostly DAC examples but one mic talk-through using ADC.
The software sampling technique causes some phase noise; the batch processing causes some latency.
These are just proof of concept examples and I haven’t developed them beyond that they seem to work.
https://github.com/bobh/ESP32AudioFramework

[alexretona]

Thank you everyone for all the suggestions. I used the hardware timer group function similar to this tutorial to implement the specific sampling rate that I need:
https://techtutorialsx.com/2017/10/07/e ... nterrupts/

I also found and tried a sample code based on the comment of ESP_igrr here:
viewtopic.php?t=1735

ESP_Sprite, I may try the I2S as an alternate method of setting my sampling rate. I will study on it first. Thank you for this!

Bobolink, thank you very much for the great project that you shared! It's great that the method that I used is similar to yours. I may further edit my code based on your project's configurations.

I will continue working with this project for the next few months. I will try my best to keep this updated.

[ShavinduR]

hello , your post was very helpful me to understand about the sampling and timers on the esp32 , currently i am trying to sample the current readings from a current transformer based circuitry by utilizing an adc port of esp32, can i now how to set specific sampling rate and get the readings .

[scottabraham]

Thank you everyone for all the suggestions. I used the hardware timer group function similar to this tutorial to implement the specific sampling rate that I need:
https://techtutorialsx.com/2017/10/07/etheessayservice.org
I also found and tried a sample code based on the comment of ESP_igrr here:
viewtopic.php?t=1735
ESP_Sprite, I may try the I2S as an alternate method of setting my sampling rate. I will study on it first. Thank you for this!

Is powering esp32 by external supply possible within this project? I am also considering using esp wroom32 module in my custom pcb.