Connect USB device and send HEX data

[demenkovms]

Hello. I connect usb card-reader to ESP32-S2

D+ --> GPIO 20
D- --> GPIO 19
VCC --> v5
GND --> GND

how I can send HEX data for it and read byte answer? Thanks!

[chiffacff]

No any idea?...

[chegewara]

There is many ways to send HEX data

• USB CDC
• USB HID

all depends what you want to achieve and what app you have on the other side

[demenkovms]

Thanks for answer. I tried to use CDC and HID from example, but it's nothing result. I use this code:

/**
 * Simple CDC device connect with putty to use it
 * author: chegewara
 * Serial - used only for logging
 * Serial1 - can be used to control GPS or any other device, may be replaced with Serial
 */
#include "cdcusb.h"
#if CFG_TUD_CDC
CDCusb USBSerial;

class MyUSBCallbacks : public CDCCallbacks {
    void onCodingChange(cdc_line_coding_t const* p_line_coding)
    {
        int bitrate = USBSerial.getBitrate();
        Serial.printf("new bitrate: %d\n", bitrate);
    }

    bool onConnect(bool dtr, bool rts)
    {
        Serial.printf("connection state changed, dtr: %d, rts: %d\n", dtr, rts);
        return true;  // allow to persist reset, when Arduino IDE is trying to enter bootloader mode
    }

    void onData()
    {
        int len = USBSerial.available();
        Serial.printf("\nnew data, len %d\n", len);
        uint8_t buf[len] = {};
        USBSerial.read(buf, len);
        Serial.write(buf, len);
    }

    void onWantedChar(char c)
    {
        Serial.printf("wanted char: %c\n", c);
    }
};


void setup()
{
    Serial.begin(115200);
    USBSerial.setCallbacks(new MyUSBCallbacks());
    USBSerial.setWantedChar('x');

    if (!USBSerial.begin())
        Serial.println("Failed to start CDC USB stack");

}

void loop() {

 if (Serial.available ())
  {
    String getCmd = Serial.readString();

    Serial.print("getCmd: ");
    Serial.println(getCmd);

    

    if (getCmd=="test") {

      Serial.println("Try send beep");

    uint8_t sendData [] = {0x4D, 0x00, 0x07}; //make beep of USB device

    USBSerial.write (sendData, sizeof(sendData));
    
Serial.println("send is ok");

    }

    Serial.println("*******************");
    



  }
}

and on get "test" command usb-device are not make beep

[chegewara]

Great
and how did you connect/wire esp32s2 board?

[demenkovms]

like I wrote in first post:

USB D+ --> GPIO 20
USB D- --> GPIO 19
USB VCC --> v5
USB GND --> GND

[chegewara]

ok, but it is only half of it
you are using Serial in your code. do you have connected USB to UART converter too?

[demenkovms]

sorry, are you about connecting esp32 to PC? - it’s over micro usb connector

[demenkovms]

or I incorrect understand your question?…

[chegewara]

With the code you posted you need to connect 2 USB cables to PC

• one for USB which you described
• one for UART which is requiring some USB to UART converter like cp210x or ftdi, so you could use and to read Serial

You can also replace all Serial with USBSerial and to have one USB connection you have right now

[demenkovms]

But, it's need connect usb device to ESP32...