Simple Sequencer

Step 9 Program the chip

Program the 16f877 chip with the following code and then transfer it into the socket.

CPU = 16F877
MHZ = 20
CONFIG = 16254

SI con A0
SCK con A1
RCK con A2

abit var byte(9)
nDur var word(8)
nP var word(8)

counter var byte
setValue var byte
noteDuration var word
notePause var word

'shift register address bits
abit(0) = %10000000
abit(1) = %01000000
abit(2) = %00100000
abit(3) = %00010000
abit(4) = %00001000
abit(5) = %00000100
abit(6) = %00000010
abit(7) = %00000001
abit(8) = %00000000

'duration array pins
nDur(0) = D0
nDur(1) = D1
nDur(2) = D2
nDur(3) = D3
nDur(4) = D4
nDur(5) = D5
nDur(6) = D6
nDur(7) = D7

'pause array pins
nP(0) = B0
nP(1) = B1
nP(2) = B2
nP(3) = B3
nP(4) = B4
nP(5) = B5
nP(6) = B6
nP(7) = B7

counter = 0
setValue = %00000000

main:

for counter = 0 to 7
HIGH nDur(counter)
pause 1
RCTIME nDur(counter),1,noteDuration

setValue = abit(counter)
gosub out595
pause noteDuration

HIGH nP(counter)
pause 1
RCTIME nP(counter),1,notePause

setValue = abit(8)
gosub out595
pause notePause * 3

next

counter = 0

goto main

out595:
shiftout SI, SCK, LSBPRE,[setValue\8]
pulsout RCK, 8
Return

Comments

[stealthop]

what pic programmer is that?

[apaterson1]

i have no programing experience do u know where i can find a pre-programmed chip? thanks

[blinkyblinky]

You can use a 4017...

[randofo]

No one sells pre-programmed chips that I know of.

[hintss]

sell them

[neutron7]

is there any way to change this program to accept an external clock source?
for instance this one will receive midi and output clock pulses.
http://www.blacet.com/MSdata.html

[randofo]

External clock from where? The PIC is getting its clock from the 20 MHZ resonator external to the chip. I don't really understand that chip enough to answer this question. What is the clock out pin actually doing?

[neutron7]

you can use MIDI to synchronise your sequencer to other music gear or programs such as reason, cubase, ableton live etc.
each time it recieves a clock is when it steps to the next value, start/stop start and stop the sequencer, and reset puts it back to the beginning.

it makes music equipment much more useful if they all know what time to do stuff.
then you can do something like this.
http://www.youtube.com/watch?v=c2HCReBtQYU