Frankenbear Synthamajig

Step 10 Program the microcontroller.

It is time to program the PIC chip. I used the Basic Micro development board and the MBasic programming environment--both of which can be found at the Basic Micro website.

The code I used can probably be converted to a more universal programming language and modified to fit your needs. Essentially, one potentiometer controls the frequency of the note and the other controls the duration of the note.

For this task the PIC chip is like using a machine to kill a mosquito. You probably can get the same effect with a 555 chip or two, but I had the PIC chip on hand at the time and felt like using it.

It is as follows:

CPU = 16F877
MHZ = 20
CONFIG 16254

screeching var word
longing var word
' sets variables

main:

HIGH B1
RCTIME B1,1,screeching
' note frequency potentiometer reading

HIGH B2,1,longing
RCTIME B2,1,longing
' note duration potentiometer reading

screeching = screeching * 2
' increases the notes frequency range

longing = longing / 12
' decreases notes duration to about 4 second maximum

if longing < 1 then
longing = 1
endif
' prevents 1 or 0 from being divided by 12 and crashing the program

FREQOUT B0,longing,screeching
' sound output on pin B0

goto main