How to enable both USB MSC (Mass Storage) and CDC simultaneously on ESP32 (Arduino framework)?

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1

Hi everyone,

I’m trying to enable both USB Mass Storage (MSC) and USB CDC (Serial) simultaneously on an ESP32 using the Arduino framework in PlatformIO.

Currently, I have the following configuration in my platformio.ini:

build_flags =
-D ARDUINO_USB_MODE=1
-D ARDUINO_USB_CDC_ON_BOOT=0

With this setup, CDC and JTAG over USB work fine.
However, when I try to initialize the MSC interface like this:

msc.vendorID(“xxxxxx”);
msc.productID(“xxxxxx”);
msc.productRevision(“xxxxxx”);
msc.onRead(OnReadFunction);
msc.onWrite(OnWriteFunction);
msc.onStartStop(OnStartStopFunction);
msc.mediaPresent(true);

if (!msc.begin(SD.numSectors(), SD.sectorSize())) {
    LOG_E(“MSC initialization failed!”);
}

USBSerial.onEvent(USBEventCallbackFunction);
USBSerial.begin(115200);

vTaskDelay(pdMS_TO_TICKS(100));

if (!USB.begin()) {
    LOG_E(“USB initialization failed!”);
}

it seems that calling USB.begin() overrides the CDC interface — MSC works, but the serial port disappears.

If I remove USB.begin(), the CDC interface works again, but MSC stops working.

So my question is:
Is it possible to enable both USB MSC and CDC simultaneously on ESP32 in the Arduino environment?
And if so, should I use ARDUINO_USB_MODE=0 and ARDUINO_USB_CDC_ON_BOOT=0 to have full control of both interfaces manually?

Any guidance or working example would be greatly appreciated!

Thanks in advance.

2

Check the example!

It starts with

#ifndef ARDUINO_USB_MODE
#error This ESP32 SoC has no Native USB interface
#elif ARDUINO_USB_MODE == 1
#warning This sketch should be used when USB is in OTG mode
void setup() {}
void loop() {}
#else

As you can see -D ARDUINO_USB_MODE=1 won’t work. You have to use -D ARDUINO_USB_MODE=0.

3

I managed to find a solution.
The issue was caused by my terminal settings and the configuration

DARDUINO_USB_MODE=1

which was being set by the board configuration. Now, by configuring only with

-DARDUINO_USB_MODE=0

I can use the USBCDC class simultaneously with USBMSC. Excellent.

PS: The MSC seems to work with both -DARDUINO_USB_MODE=0 and -DARDUINO_USB_MODE=1. It’s a specific condition of that example, not a general one.