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zephyr/samples/subsys/usb/cdc_acm
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Gerard Marull-Paretas 79e6b0e0f6 includes: prefer <zephyr/kernel.h> over <zephyr/zephyr.h> 
As of today <zephyr/zephyr.h> is 100% equivalent to <zephyr/kernel.h>.
This patch proposes to then include <zephyr/kernel.h> instead of
<zephyr/zephyr.h> since it is more clear that you are including the
Kernel APIs and (probably) nothing else. <zephyr/zephyr.h> sounds like a
catch-all header that may be confusing. Most applications need to
include a bunch of other things to compile, e.g. driver headers or
subsystem headers like BT, logging, etc.

The idea of a catch-all header in Zephyr is probably not feasible
anyway. Reason is that Zephyr is not a library, like it could be for
example `libpython`. Zephyr provides many utilities nowadays: a kernel,
drivers, subsystems, etc and things will likely grow. A catch-all header
would be massive, difficult to keep up-to-date. It is also likely that
an application will only build a small subset. Note that subsystem-level
headers may use a catch-all approach to make things easier, though.

NOTE: This patch is **NOT** removing the header, just removing its usage
in-tree. I'd advocate for its deprecation (add a #warning on it), but I
understand many people will have concerns.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
2022-09-05 16:31:47 +02:00
..
src includes: prefer <zephyr/kernel.h> over <zephyr/zephyr.h> 2022-09-05 16:31:47 +02:00
app.overlay samples: subsys: Remove label property from devicetree overlays 2022-07-19 10:30:20 +02:00
CMakeLists.txt cmake: increase minimal required version to 3.20.0 2021-08-20 09:47:34 +02:00
Kconfig
overlay-composite-cdc-dfu.conf
overlay-composite-cdc-msc.conf tests/boards/samples: fixup after sdmmc driver relocation 2021-03-23 12:16:01 +01:00
prj.conf samples: usb: get CDC ACM UART device from devicetree 2021-08-23 18:53:47 -04:00
README.rst
sample.yaml samples: fix wrong extra_args definitions 2022-01-04 17:15:06 -05:00

README.rst 

.. _usb_cdc-acm:

USB CDC ACM Sample Application
####################################

Overview
********

This sample app demonstrates use of a USB Communication Device Class (CDC)
Abstract Control Model (ACM) driver provided by the Zephyr project.
Received data from the serial port is echoed back to the same port
provided by this driver.
This sample can be found under :zephyr_file:`samples/subsys/usb/cdc_acm` in the
Zephyr project tree.

Requirements
************

This project requires an USB device driver, which is available for multiple
boards supported in Zephyr.

Building and Running
********************

Reel Board
===========

To see the console output of the app, open a serial port emulator and
attach it to the USB to TTL Serial cable. Build and flash the project:

.. zephyr-app-commands::
   :zephyr-app: samples/subsys/usb/cdc_acm
   :board: reel_board
   :goals: flash
   :compact:

Running
=======

Plug the board into a host device, for example, a PC running Linux.
The board will be detected as shown by the Linux dmesg command:

.. code-block:: console

   usb 9-1: new full-speed USB device number 112 using uhci_hcd
   usb 9-1: New USB device found, idVendor=8086, idProduct=f8a1
   usb 9-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
   usb 9-1: Product: CDC-ACM
   usb 9-1: Manufacturer: Intel
   usb 9-1: SerialNumber: 00.01
   cdc_acm 9-1:1.0: ttyACM1: USB ACM device

The app prints on serial output (UART1), used for the console:

.. code-block:: console

   Wait for DTR

Open a serial port emulator, for example minicom
and attach it to detected CDC ACM device:

.. code-block:: console

   minicom --device /dev/ttyACM1

The app should respond on serial output with:

.. code-block:: console

   DTR set, start test
   Baudrate detected: 115200

And on ttyACM device, provided by zephyr USB device stack:

.. code-block:: console

   Send characters to the UART device
   Characters read:

The characters entered in serial port emulator will be echoed back.

Troubleshooting
===============

If the ModemManager runs on your operating system, it will try
to access the CDC ACM device and maybe you can see several characters
including "AT" on the terminal attached to the CDC ACM device.
You can add or extend the udev rule for your board to inform
ModemManager to skip the CDC ACM device.
For this example, it would look like this:

.. code-block:: none

   ATTRS{idVendor}=="8086" ATTRS{idProduct}=="f8a1", ENV{ID_MM_DEVICE_IGNORE}="1"

You can use
``/lib/udev/rules.d/77-mm-usb-device-blacklist.rules`` as reference.