USB Host UART Interface

This component allows an ESP32-S3 or ESP32-S2 to host USB-serial peripheral devices. It uses the Usb Host component to interface to the device as a USB-OTG host.

Currently supported devices are listed in the table below:

Supported Devices

Name	VID	PID	Description
CH34X	0x1A86	0x55D5	USB to serial adapter, multi-channel (up to 3 channels)
CH340	0x1A86	0x7523	USB to serial adapter, single channel
ESP_JTAG	0x303A	0x1001	ESP32 JTAG interface
STM32_VCP	0x0483	0x5740	STM32 Virtual COM Port
CDC_ACM	0x0000	0x0000	USB CDC ACM (Abstract Control Model)
CP210X	0x10C4	0xEA60	Silicon Labs USB to UART Bridge

# Example minimal configuration entry
usb_uart:
  - type: cp210x
    channels:
      - id: uch_1
        baud_rate: 9600
        buffer_size: 1024

Configuration variables

• id (Optional, ID): The id to use for this component.
• type (Required, string): The type of USB-serial device to connect to. One of ch34x, ch340, esp_jtag, stm32_vcp, cdc_acm, cp210x.
• channels (Required, list): A list of channels to configure.
• vid (Optional, int): The vendor ID of the device. Use 0 as a wildcard. Each type has a default VID which will be overridden if this is set.
• pid (Optional, int): The product ID of the device. Use 0 as a wildcard. Each type has a default PID which will be overridden if this is set.

Setting both vid and pid to 0 will match any device.

Channel configuration options

• id (Optional, ID): An id to assign to the channel. This id may be used anywhere a uart component is required.
• baud_rate (Required, int): The baud rate to use for the channel. This is optional (and ignored) for the stm32_vcp, esp_jtag and cdc_acm types.
• buffer_size (Optional, int): The size of the buffer to use for the channel. Defaults to 256 bytes.
• stop_bits (Optional, float): The number of stop bits to use. Defaults to 1. Other options are 1.5 and 2.
• data_bits (Optional, int): The number of data bits to use in the range 5-8. Defaults to 8.
• parity (Optional, string): The parity to use. One of NONE, EVEN, ODD, MARK and SPACE. Defaults to NONE.
• dummy_receiver (Optional, boolean): If set to true, the channel will consume any data received. This is useful for debugging purposes. Defaults to false.
• debug (Optional, boolean): If set to true, the channel will log all data sent and received. Defaults to false.
• debug_prefix (Optional, string): A string prepended to every debug log line for this channel. Useful when multiple channels have debugging enabled, to distinguish their output in the log. Defaults to "".
• flush_timeout (Optional, Time): The maximum time to wait for the USB output queue to drain when flush() is called. If the queue does not drain within this time, flush() returns a TIMEOUT result. Defaults to 100ms.

Device types

The cdc_acm type is a generic USB CDC ACM (Abstract Control Model) device. This is a common USB device class for serial communication. This driver does not strictly enforce the CDC-ACM configuration specification, so it may work with devices that do not properly implement that specification. It expects to find a single interrupt endpoint, a single bulk in endpoint, and a single bulk out endpoint. The cdc_acm, esp_jtag and stm32_vcp types do not support changing baud rate, stop bits or number of data bits, as they implement a virtual channel not typically associated with a physical UART.

See Also

• USB Host Interface
• API Reference: usb_uart.h