Patchell Windows Programming Page
January 1, 2005
March 9, 2005
Overlapped RS232 Programming
If you have ever tried to write a program that
accessed the comm ports under Win32, you have probably been overwhelmed
by the large number of convoluted functions you have to deal with in
order to do this. It is posible to open up the RS232 port on
Non-overlapped mode, however, there are several problems with doing
this, and if you have done it, you may have run into them. By
using the overlapped mode, the comm ports do work pretty much as you
would expect, although, still not, in my opinion, perfectly. Of
course, there are probably still some features I don't know about that
would even cure these problems.
What you will find here is a zip file of a skeleton
program that opens up an RS232 port and provides functions for reading
and writing to the port.
Now, one of the problems still with using the
Overlapped mode is that you need to have a thread that reads the
characters that come back into the PC. In the code, you will find
this in a function called WorkerThread.
Yeah, not exactly an original name, but what the heck. This
worker thread is pretty simple. It reads the character in and
prints it into a static text box in the main dialog. Now in a
real program you will most likely have some sort of parser, be it
simple or complex, that will look for messages in the data coming
back. Once you have located your messages you can do several
things. You can act on them directly, or you can send a
notification back to the main dialog box by using PostMessage and sending user defined
messages, just like I did for the message that notifies the main dialog
box that the thread has stopped.
As of January 1, 2005, I have not actually tested
this code, although, most of it has been used before (that is no
garentee). Still for the time being, it should give you a good
idea of how to proceed.
Source Code for
Soft Synth for MicroSquish Window
This is a very simple softsynth that I did for
running under Microsoft Windows. It should run with Windows98,
Windows2000, Windows XP and Windows ME. I have only tried it on
Windows XP running on a 2GHz Pentium. There is a chance a slower
computer could sound strange. So, what you will find here is the
source code and an executable for a very simple program that compiles,
hopefully, with Microsoft Visual C++ 6.0. I cannot predict what
it will do with other versions of the compiler.
There is not a whole lot that I can think of to say
about this program. Basically, I open up an audio out channel and
set up two buffers. The buffers are then ping-ponged as they
empty out. There is a synth engine routine that is called that
fills the buffers up with data when a buffer is ready.
Oh, yes, there is a simple little sequencer that
plays a couple of little tunes.
The modules that I implemented are a VCO, Multimode
VCF, VCA, and a simple envelope generator.
Source Code for Soft Synth