Serial hardware plus standalone license-free OCX software.

Many PIC project developers would like to be able to interface their designs with a PC’s serial port, but encounter several difficulties. The principal one for those readers using Visual Basic on their PC is that not all versions of VB allow access to the MSCOMM Active-X serial communications control function. Whilst there are “work-arounds” to this problem, they have varying degrees of success.

The other problem is that serial port voltages can vary considerably from PC to PC, and these voltages need to be converted to standard TTL voltage levels to enable connection to a PIC.

The project described here provides a two-fold solution to this problem. Firstly, a small circuit board is described that allows safe interfacing between a PC and a PIC, or other digital design. Secondly, and importantly, a freeware Active-X (OCX control) software component suitable for use with all versions of Visual Basic 6 is provided and its use described. This software allows the developer complete access to the serial port and its pins and is compatible with all current versions of Microsoft Windows, namely 95, 98, ME, NT4, 2000 and XP. It can be used with other designs without the interface board described here.