ESP32 WROOM 32E - GPIO 0 MCLK Signal Problems

[CCooper1971]

Hi,

I have designed a PCB using the ESP32 WROOM, after building a successful prototype. However, on the prototype, my GPIO 0 MCLCK signal is OK

Please see image DS0001.PNG

While on my new PCB, the signal is noisy, please see image DS0002.PNG

I have designed the board using the Espressif reference diagram, also attached ESP32-DevKitC-V4_SCH_20180607A.pdf.

The reset and boot circuitry is identical and I have reviewed my PCB many times, cross referencing and cannot see any errors. I have also used this design previously and it works.

I am wondering if there is a firmware issue or difference on the ESP which is causing a conflict with GPIO 0?

Please note, that I am using the same code on both the prototype and the finished PCB and except for some pin changes, which I have also checked to ensure they do not cause a problem, they are the same.

Code: Select all

// New Board

#define blueLED 25
#define greenLED 26
#define amberLED 12
#define redLED 15

#define blackButton 35
#define redButton 39

// Prototype Board

//#define greenLED 25
//#define amberLED 26
//#define redLED 12
//#define whiteLED 15

//#define blackButton 36
//#define redButton 39

[CCooper1971]

Hi All,

For those who experience the same problem when using the reference designs, I have solved it as follows.

When reviewing the diagram supplied by Espressif, see initial post. C15, which is a 0.1uF debounce capacitor on the Boot switch causes, the MCLK to be smoothed. Upon removing said debounce capacitor, the MCLK signal works a treat, please see image.

DS0003.PNG (9.08 KiB) Viewed 1798 times

My Class D I2S Amplifier Board now makes sound, hurrah!

Regards,

Christopher