wehub-resource-sync
112 lines
5.2 KiB
Markdown
112 lines
5.2 KiB
Markdown
| Supported Targets | ESP32-H4 | ESP32-P4 | ESP32-S2 | ESP32-S3 | ESP32-S31 |
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# USB CDC Host Driver Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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## Overview
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This example demonstrates how to use the [CDC-ACM Host Driver](https://components.espressif.com/components/espressif/usb_host_cdc_acm) together with VCP drivers to enable an ESP chip to communicate with USB CDC devices, including vendor-specific USB-to-UART converters (e.g., [CP210x](https://components.espressif.com/components/espressif/usb_host_cp210x_vcp), [FTDI FT23x](https://components.espressif.com/components/espressif/usb_host_ftdi_vcp), [CH34x](https://components.espressif.com/components/espressif/usb_host_ch34x_vcp)). CDC-ACM is a USB device class specification that allows USB devices to appear as serial ports, commonly used by USB-to-UART converters and virtual COM port devices.
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The example performs the following operations:
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1. Installs the USB Host Library and CDC-ACM driver
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2. Waits for CDC devices to be connected
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3. Opens the device using the appropriate driver based on VID/PID
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4. Prints the device descriptor information
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5. Sends test data to the device
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6. Receives data from the device (handled via callback)
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7. Demonstrates line coding commands (get/set baud rate, data bits, stop bits, parity)
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8. Demonstrates control line state commands (DTR/RTS)
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9. Handles device disconnection and allows connecting another device
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## How to use example
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### Hardware Required
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* Development board with USB-OTG support that will act as USB host
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* USB CDC device. This can be:
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- A USB-to-UART converter (e.g., CP210x, FTDI FT23x, CH34x)
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- Another ESP development board configured as a USB serial device (see [tusb_serial_device example](../../device/tusb_serial_device))
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- Another ESP development board connected with USB-Serial-JTAG
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- Any other USB device that implements the CDC-ACM class
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#### Pin Assignment
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Follow instructions in [examples/usb/README.md](../../README.md) for specific hardware setup.
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### Build and Flash
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1. Prepare the USB CDC device:
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- If using a USB-to-UART converter, no preparation is needed
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- If using another ESP board as a USB device, build and flash the [tusb_serial_device example](../../device/tusb_serial_device) to that board first
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2. Connect the CDC device to the USB Host port
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3. Build this project and flash it to the USB host board, then run monitor tool to view serial output:
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```bash
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idf.py -p PORT flash monitor
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```
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(Replace PORT with the name of the serial port to use.)
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(To exit the serial monitor, type ``Ctrl-]``. To stop the example, press the Boot button on the board.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example Output
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After flashing and connecting a CDC device, you should see output similar to the following in the idf monitor:
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```
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I (256) usb_task: Running USB task
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I (256) usb_task: - Installing USB Host
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I (266) usb_task: - Installing CDC-ACM driver
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I (276) app_main: Waiting for CDC devices. Press Boot button to quit.
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I (584) USB-CDC: New CDC device connected VID=0x10C4 PID=0xEA60
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I (594) USB-CDC: CDC device opened (slot 0). Descriptor:
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...
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I (1154) USB-CDC: Testing data transmission
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I (1174) USB-CDC: - Data received (slot 0)
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I (1174) USB-CDC: 0x4ffbf640 43 44 43 20 74 65 73 74 20 73 74 72 69 6e 67 21 |CDC test string!|
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I (1274) USB-CDC: Testing control line state command
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I (1294) USB-CDC: - Control line state set to DTR=false, RTS=true
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I (1314) USB-CDC: Testing line coding commands
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I (1314) USB-CDC: - Line Coding Get: Rate: 115200, Stop bits: 0, Parity: 0, Databits: 8
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I (1314) USB-CDC: - Line Set: Rate: 115200, Stop bits: 0, Parity: 0, Databits: 8
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I (1314) USB-CDC: Example finished for device in slot 0. You can disconnect or connect another device.
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```
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## Troubleshooting
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### Device Not Detected
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If the CDC device is not detected, check:
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1. **USB connection:** Ensure the device is properly connected to the USB host port
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2. **Device compatibility:** Verify that the device implements the CDC-ACM class or is a supported VCP device (CP210x/FTDI/CH34x). Some USB-to-UART converters may use proprietary drivers
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3. **Power supply:** Ensure the USB host port provides adequate power for the connected device
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4. **Cable quality:** Use a quality USB cable that supports data transfer (not charge-only cables)
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### No Data Received
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If data is sent but not received:
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1. **Check device connection:** Ensure the device is still connected and enumerated
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2. **Verify device functionality:** Test the device with another host to confirm it's working
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3. **Check line coding:** Some devices may require specific line coding settings before they start transmitting data
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4. **Increase log level:** Set the log level to debug via `idf.py menuconfig` to get more detailed information
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### Line Coding Commands Not Supported
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If you see warnings like:
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```
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W (xxx) USB-CDC: Line coding get not supported
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W (xxx) USB-CDC: Control line state set not supported
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```
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This is normal for some CDC-ACM devices that don't support these optional commands. The example will continue to work for basic data transfer operations.
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