Pololu Wixel User Manual download pdf (Page 28)

6. Using a Virtual COM Port

Most of the available Wixel apps implement a USB interface that consists of a single virtual COM (serial) port. This

interface allows you to send and receive bytes from the Wixel in the same way you would send and receive bytes

from any other serial port on your computer.

6.a. Determining the Port Name

To connect to a COM port, you usually have to know the name of the port.

In Windows, the port name will be something like “COM4” and you can determine the port name by selecting the

Wixel in the Wixel Configuration Utility and looking at the “Port Name” property displayed below. You can also find

out the port name by looking the “Ports (COM & LPT)” list in your Device Manager.

Windows Tip: Besides having names like “COM5” and “COM6”, the virtual COM ports provided by

the Wixel also have names like “\\.\USBSER000” and “\\.\USBSER001”. These names are assigned

sequentially whenever a device with a virtual COM port is plugged in. If you only have one device

with a virtual COM port plugged into your computer, the name “\\.\USBSER000” will usually be

assigned to it. These names will work with most programs that allow you to specify arbitrary port

names.

6.b. Using a Terminal Program

There are many free terminal programs available which are capable of sending and receiving bytes on a virtual COM

port. These programs include PuTTY [http://www.chiark.greenend.org.uk/~sgtatham/putty/] (Windows or Linux), Tera

Term [http://ttssh2.sourceforge.jp/] (Windows), and Br@y Terminal [http://sites.google.com/site/terminalbpp/] (Windows).

Advanced users developing scripted applications may prefer the free terminal program kermit [http://www.columbia.edu/

kermit/ck80.html]. To use any of these terminal programs with the Wixel, you must specify the port name (see Section

6.a) and the baud rate. The baud rate may or may not affect anything; see your application’s documentation. The

characters you type will be transmitted on the programmer’s TX line. Bytes received by the programmer on the RX

line will be displayed on the screen by the terminal program.

Typical terminal programs will allow you to choose several other settings besides the baud rate. If you are not sure

what settings to use, then you should pick 8 data bits, 1 stop bit, no parity, and no flow control.

Typical terminal programs will not allow you to use the serial control signals, but Br@y terminal does. You can click

the “DTR” and “RTS” buttons to change the state of the DTR and RTS signals. The state of the CTS, CD, DSR, RI,

DTR, and RTS signals are indicated by the colors of the corresponding buttons.

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Pololu Wixel User Manual Page 28