button press AND hserout issues?!

[Giulio]

So... I dug out my ICD2 and selection of pics, to build myself a MIDI foot controller. Not having played with MIDI before, I set up a 16f628a, and tried the following:

DEFINE HSER_TXSTA 24H
DEFINE HSER_BAUD 31250

main:

[set relevant ports and CMCON, etc...]

loop:
hserout [144,90,90]
goto loop

Voila! My MIDI analyser shows note on, channel 1, regular as clockwork. Next, I need to send differing messages dependent on one of [n] push-to-make footswitches, so I tried:

if not porta.1 then
hserout [144,90,90]
endif

FAIL! Whereas the analyser was consistent before, now it fails every so often, showing error messages/system reset errors, etc., which leads me to believe there are timing issues with the USART that the if...then and porta.0 test is causing.


I don't want to write a hserout equivalent in assembler, as that's the whole point of using PicBasic Pro, but the timing issues and the button press test are making what should have been a simple project quite frustrating...

I feel that there's not enough documentation available which explains precisely which resources a given command uses, borne out of other frustrating isues I've had with timers, serial LCD display, etc...

Can anybody shed any light on this, or is it back to assembler for this whole project???

G

[mackrackit]

Have you turned of the analog on PORTA?

[Giulio]

Yes, I didn't want to waste space by showing my initialisation code, but:

CMCON = 7

and to isolate the one switch for testing:

TRISA = %00000010



G

[mackrackit]

if not porta.1 then
hserout [144,90,90]
endif

FAIL! Whereas the analyser was consistent before, now it fails every so often, showing error messages/system reset errors, etc., which leads me to believe there are timing issues with the USART that the if...then and porta.0

You may want to post your whole code...

[Giulio]

The porta.0 was a typo in my message - the code was exact. This works, every time, and doesn't skip a beat:


define OSC 20

DEFINE HSER_TXSTA 24H
DEFINE HSER_BAUD 31250

main:

CMCON = 7
TRISA = %00000010
TRISB = 0


loop:

hserout [144,90,90]

goto loop

;---------------------------------------

This also works some of the time, but midi analyser shows 'error' periodically, and results are spurious:


define OSC 20

DEFINE HSER_TXSTA 24H
DEFINE HSER_BAUD 31250

main:

CMCON = 7
TRISA = %00000010
TRISB = 0


loop:

if not porta.1 then
hserout [144,90,90]
endif

goto loop

;-------------------------------------

As I said, the if...then, and the test for button is most certainly doing something to the hserout command. I've tried putting a PAUSE [x] before and after and both before and after the hserout command, and it just slows things up, and still produces errors at the midi analyser... ???


G

[cncmachineguy]

Just for kicks, change the loop label to something other then loop. That is a keyword in later releases and maybe it is playing up on the IF?

And maybe put a check after the HSEROUT to check if the transmission is done. Maybe the transmission is colliding with the next time through loop since there is nothing else to do? Of course that doesn't explain why the first one works.