UT-2303 USB to Serial Converter Cable
I went thrifting a little bit ago and found a mysterious unmarked small black box with a DB9 connector on one end and a USB cable coming out the other. I wonder what it is..
I am familiar with the FTDI USB serial chips, so I was hoping this device would employ one. It was cheap enough that if it wasn't exactly what I was looking for, I could either junk it or use the cable, DB9 jack and case in an upcoming project. So of course I got it and opened it up as soon as I got home. To my dismay it didn't use an FTDI chip, instead it's got a Prolific PL-2303X chip doing the TTL-level RS232 to USB conversion. From there it's got a Sipex SP213ECA RS232 level translator to bring down the ~12 Volt RS232 levels to TTL levels (5 Volts). This is all pretty standard as far as USB to serial cables go. The part that was missing was the driver for my PC.
Before I cracked it open I plugged it into my PC running XP just to see if it would enumerate and install some random driver, perhaps the FTDI one that I already have setup for use with my Bus Pirate. Of course it didn't, but you just can't stop there. If you have a mysterious USB device and are looking for the driver, the first thing you should do after plugging it into your PC is to go to your device manager on your PC.
In XP this is Control Panel-System-Hardware-Device Manager. Go down to Ports (COM and LPT) and find the unknown USB device. Right click Properties. Under the Details tab you will have a drop-down list. There is alot of info there, but what you are looking for is the Device Instance ID. For my USB to serial cable the Device Instance ID states USB\\VID_067B&PID_2303\5&3AE50938&0&2. The only part that is of interest is the VID and PID. VID is the Vendor ID and it states what company made the USB chip in your device. The PID is the Product ID. VID 067B is Unixtar Technology and PID 2303 is the PL-2303X. Doing a quick search of the VID and PID easily provided me with the needed driver.
It installs and enumerates. Here it is connected to the BDM POD on my Freescale HCS12 board running the D-Bug12 monitor program. So far this USB to Serial cable works pretty good.
Not bad for $2.