Wednesday, March 9, 2011

Hardware UARTs under Windows 7: Yes, it is possible

There are many reasons to want a real hardware UART on a desktop PC. In my case, we use a number of embedded systems and devices (e.g. Cisco 678 DSL modem, UARTs on TStik) which require an asynchronous serial connection at up to 115200 baud. In addition we need to be able to use some legacy software (e.g. javaxcomm which is recently changing under Oracle), as well as scriptable serial terminal software (e.g. RealTerm) to communicate with embedded systems, sensors, and devices.

Similarly, we have the need for a true hardware IEEE1284 parallel port with EPP mode to use with ;egacy  JTAG adapters for Xilinx and legacy hardware such as JStamp and JStik.

BUT most new PCs have only USB (and things like RS232 handshaking signals are sometimes not properly functional on USB virtual COM ports) and Windows 7 no longer includes Hyperterminal (no great loss IMO). So the common (mis)perception is that hardware UARTs and software to access them are difficult or impossible under Windows 7. Ditto for IEE1284 true parallel ports with EPP mode (not just printer-capable ports).

Today I am building new Windows 7 64-bit PCs and wanting a solution for this, along with many of our customers. I'm using the MSI 890FXA-GD70 motherboard

And I am happy to say that real hardware UARTs are possible under Windows 7.

Here is the Rosewill RC303 at Newegg. This under-$20, PCI-bus card has two serial and one parallel port. So far I am able to use the hardware UARTs with RealTerm. I will add to this with more information as it develops.