This USB-to-UART converter provides an easy-to-use, small-footprint, cost-effective option for adding USB connectivity to existing systems which have an UART.

This tiny little adapter uses the MCP2200 from Microchip. It has a 64 bit RX and TX buffer and is housed in a SSOP-20 package. A 12 MHz crystal ensures precise timing. The UART controller can handle up to 19200 bits, 8 data bits, no parity, 1 stop bit. (for 0% error). It is equipped with a 256 byte eeprom and various GPIO (which are not used). The board is equipped with three leds which indicated the status. (Power, RX, TX). The used 6-pin header has always the same pin assignment, so they (RS232,USB,XPORT,...) are all interchangeable. Please be aware that the RX/TX pin marking on the MCP2200 (datasheet) is from the point of view of the computer !

The device must be configured before use. Microchip offers several tools to do so. You may freely choose a VID (vendor ID) and PID (product ID) as long as your project will not escape your lab. (In case you leave the door open : a wrong driver may be loaded :-) So be careful ! You may lock yourself out when using a different VID (default:0x04D8)

We suggest you use the following settings : (Tools are from Microchip Website)

The device may easily be tested using HTerm in a loopback configuration. (RX is tied to TX and so the data is send back to the computer).

As the name 'bus' suggests, there are more 'passengers' travelling. Therefore a header with some destination information has to be added. This may explain, that the data on the usb-bus must travel much faster and, that 'your' passenger is hard to be spotted out. The picture on the left shows the signals on D+ (top) and D- (bottom). If traffic looks like that, you may assume, that the bus is working properly. For the youngplayers among you, it is therefore recommended to start with a proven design, so you can take care of the data at the output of the MCP2200 or whatever else solution is used.

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