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
Terminal emulation software such as Minicom can be used to communicate with CY7C64225 and stream data using the following procedure:
- Open Minicom on a terminal by pressing [Ctrl] [A] and then Z, this will open the Minicom menu.
- Press O to configure Minicom.
- In the Configuration window, select Serial Port Setup.
- Press A and then type dev/ttyACM0 to select the Serial Device.
- Press E to configure the Baud Rate in the same window.
- 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.
- 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: https://help.ubuntu.com/community/Minicom
Figure 3. Loop Back Test Using Minicom