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Testing a USB-Serial Bridge Controller Configured as USB-UART with Linux® – KBA92551

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Testing a USB-Serial Bridge Controller Configured as USB-UART with Linux® – KBA92551

Version: *A


Question: How do you test a Cypress® USB -Serial Bridge Controller configured as USB-UART with the Linux®OS?



The USB driver stack in Linux has a built-in driver for Communication Device Class Abstract Control Model (CDC ACM) devices. The USB-Serial device configured as a CDC UART binds to the Linux CDC ACM driver automatically and creates a device node in “ /dev/ttyACM* ”. Figure 1 lists the device as available.

Note: * is a wildcard to represent the number of the device node. The name of the device node varies based on the number of devices connected. With one device, the kernel creates the /dev/ttyACM0 node, which the application uses to communicate with the device.

Figure 1: Linux Terminal Listing the Device as Connected


Figure 2 shows that the CY7C65213 device is connected and the node has been created in the “/dev” folder with the name ttyACM0, as described earlier.

Figure 2: CY7C65213 Node Created in “/dev” Folder

dev folder

Terminal emulation software such as Minicom can be used to communicate with CY7C64225 and stream data using the following procedure:

  1.   Open Minicom on a terminal by pressing [Ctrl] and then Z, this will open the Minicom menu.
  2.   Press O to configure Minicom.
  3.   In the Configuration window, select Serial Port Setup.
  4.   Press A and then type dev/ttyACM0 to select the Serial Device.
  5.   Press E to configure the Baud Rate in the same window.
  6.   For simple loopback tests, short the RXD and TXD pins of the USB-Serial device on the board. Send a few characters using your keyboard. The characters you entered will be displayed on the terminal as shown in Figure 3.
  7.   Press Esc to leave the active window and select save set up as in the previous window. Exit Minicom.

Figure 3 shows the loopback test result using Minicom. For more information on using Mincom use the following link:

Figure 3. Loop Back Test Using Minicom

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