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9049230e4a
esp-idf/examples/peripherals/usb/host/cdc/common/cdc_acm_host
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Tomas Rezucha 9049230e4a usb_host: Rename symbols that conflict with TinyUSB
2022-03-21 18:34:25 +01:00
..
include/usb usb_host: Rename symbols that conflict with TinyUSB 2022-03-21 18:34:25 +01:00
test ci: Add USB Host CDC and MSC pytests to pipeline 2022-03-21 18:34:24 +01:00
cdc_acm_host.c usb_host: Rename symbols that conflict with TinyUSB 2022-03-21 18:34:25 +01:00
CMakeLists.txt usb_host: Don't build CDC host driver for unsupported targets 2022-03-17 13:10:29 +01:00
README.md usb: Add USB host CDC-ACM class driver 2021-12-09 10:28:46 +01:00

README.md

USB Host CDC-ACM Class Driver

This directory contains an implementation of a USB CDC-ACM Host Class Driver that is implemented on top of the USB Host Library.

Supported Devices

The CDC-ACM Host driver supports the following types of CDC devices:

  1. CDC-ACM devices
  2. CDC-like vendor specific devices (usually found on USB to UART bridge devices)

CDC-ACM Devices

The CDC-ACM Class driver supports CDC-ACM devices that meet the following requirements:

  • The device class code must be set to the CDC class 0x02 or implement Interface Association Descriptor (IAD)
  • The CDC-ACM must contain the following interfaces:
    • A Communication Class Interface containing a management element (EP0) and may also contain a notification element (an interrupt endpoint). The driver will check this interface for CDC Functional Descriptors.
    • A Data Class Interface with two BULK endpoints (IN and OUT). Other transfer types are not supported by the driver

CDC-Like Vendor Specific Devices

The CDC-ACM Class driver supports CDC-like devices that meet the following requirements:

  • The device class code must be set to the vendor specific class code 0xFF
  • The device needs to provide and interface containing the following endpoints:
    • (Mandatory) Two Bulk endpoints (IN and OUT) for data
    • (Optional) An interrupt endpoint (IN) for the notification element

For CDC-like devices, users are responsible for ensuring that they only call APIs (e.g., cdc_acm_host_send_break()) that are supported by the target device.

Usage

The following steps outline the typical API call pattern of the CDC-ACM Class Driver

  1. Install the USB Host Library via usb_host_install()
  2. Install the CDC-ACM driver via cdc_acm_host_install()
  3. Call cdc_acm_host_open()/cdc_acm_host_open_vendor_specific() to open a target CDC-ACM/CDC-like device. These functions will block until the target device is connected
  4. To transmit data, call cdc_acm_host_data_tx_blocking()
  5. When data is received, the driver will automatically run the receive data callback
  6. An opened device can be closed via cdc_acm_host_close()
  7. The CDC-ACM driver can be uninstalled via cdc_acm_host_uninstall()

Examples