ESP-WROOM-32 & SDMMC & CH340G

[don.vukovic]

I need some advice.
I have designed a PCB using a ESP-WROOM-32 & SDMMC & CH340G.
The problem is that the CH340G uses the two transistors for set the programming mode.
If I have an SD card inserted into it's socket, the WROOM will not go into programming mode.
I release the SD card, and its fine.

Is there a correct schematic where the SD card does not interfere with the Boot process.
I know its the IO2 pin.
What is the proper circuit ?

The schematic attached is my pcb schematic.

SDMMC.pdf

(28.89 KiB) Downloaded 670 times

[ESP_igrr]

Please have a look at the wrover-kit schematic (https://docs.espressif.com/projects/esp ... s.html#id8). It has the additional transistor on GPIO2 to pull it low when entering download mode.

[don.vukovic]

I added the extra isolation transistor, but I have the same proble.
I can not go into programming mode with the SD card inserted.

Please see attached schematic.

[WiFive]

Did you check oscilloscope? Maybe EN pin goes high before IO2 goes low because of no cap on EN + strong pull-up, and capacitive effects of SD card on IO2?