Pololu Wixel User Manual download pdf (Page 37)

Wixel programmable USB wireless

module (fully assembled) with USB cable

connected.

9.c. USB-to-Serial App

Overview

This app allows you to turn a Wixel into a USB-to-TTL serial

adapter capable of baud rates up to 350,000 bps. While this app does

not use the radio, it has more features than the USB-to-UART mode

of the Wireless Serial App (see Section 9.b).

Installation Instructions

Download the USB-to-Serial App (v1.0) [http://www.pololu.com/file/

download/usb-serial-v1.0.wxl?file_id=0J464] (13k wxl). Open it with the

Wixel Configuration Utility and write it to a Wixel. See Section 4

for more information on how this is done.

Pinout

Pin Function

P1_0 DTR general purpose output pin controlled by computer

P1_1 RTS general purpose output pin controlled by computer

P1_2 DSR general purpose input pin reported to computer

P1_3 CD general purpose input pin reported to computer

P1_6 TX transmits serial data from computer

P1_7 RX receives data and sends it to the computer

Description

After you have loaded this app onto a Wixel, the Wixel will appear to the computer as Virtual COM Port (with USB

product ID 0x2200). If you are using Windows, you should see an entry labeled “Wixel” in your Device Manager

in the “Ports (COM & LPT)” category while the app is running. You can connect to this COM port using a terminal

program in order to send and receive data on the TX and RX lines. Typical terminal programs will allow you to set

the baud rate, parity type, and number of stop bits. Some terminal programs will allow you to use the control signals

(DTR, RTS, DSR, and CD). For more information, on how to use a virtual COM port, see Section 6.

This app supports all integer baud rates between 23 and 350,000 bps.

This app supports all the different types of parity: None, Odd, Even, Mark and Space.

This app supports 1 stop bit or 2 stop bits mode.

The RX line has an internal pull-up resistor, so you can leave this line disconnected.

The DSR and CD input pins have internal pull-up resistors, so when they are disconnected they will read as high

(logical 0).

The DTR and RTS output pins are designed for high current (see the information on P1_0 and P1_1 in Section 1.a).

The control signals are all inverted, which means that a logical 0 corresponds to a high voltage (3.3 V) and a logical

1 corresponds to a low voltage (0 V).

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Pololu Wixel User Manual Page 37