Who sees my stupid mistake?

[RuudNL]

Hello,

After not having used picbasic for a couple of years, I decided to create some code to produce MIDI information.
The intended use is to have five buttons to control a DAW.
The code compiles without a problem, but I don't get any MIDI (31.250 Baud) output. Xtal = 20 MHz, PIC = 16F628.
I think I made an obvious mistake, but I don't see what it could be...

'* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
'* MIDI Remote for Reaper            20 MHz resonator (HS)          
'* PIC16F628                         Watchdog timer OFF              
'* PORTA.0 = Output                                                  
'* PORTB.0 = Rewind                                                  
'* PORTB.1 = FastFwd.                                               
'* PORTB.2 = Stop                                                   
'* PORTB.3 = Play                                                   
'* PORTB.4 = Record                                                 
'* PORTB.5 = Switch between: Stop / Stop + Save
'* Version 1.0                                      
'* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 

TRISB= %00111111                                 ' PORTB.6/7=Output 0..5=Input
CMCON =  7                                             ' Digitale mode
DEFINE OSC 20                                        ' 20 MHZ OSC.

Progstart: 

  if PORTB.0 = 1 then 
    Serout2 PORTB.7, 16384+12, [144, 44, 127]    ' Rewind
  endif  
  if PORTB.1 = 1 then 
    Serout2 PORTB.7, 16384+12, [144, 46, 127]    ' Fast Fwd.
  endif  
  if PORTB.2 = 1 then 
    if PORTB.5 = 0 then                          ' Normal STOP mode
      Serout2 PORTB.7, 16384+12, [144, 48, 127]  ' Stop
    else
      Serout2 PORTB.7, 16384+12, [144, 54, 127]  ' Stop + Save
    endif    
  endif  
  if PORTB.3 = 1 then 
    Serout2 PORTB.7, 16384+3313, [144, 50, 127]  ' Play  
  endif  
  if PORTB.4 = 1 then 
    Serout2 PORTB.7, 16384+3313, [144, 52, 127]  ' Record
  endif  

Debounce:
  Pause 20                                          ' ? shorter ?
  If (PORTB.0=1) or (PORTB.1=1) or (PORTB.2=1) or (PORTB.3=1) or (PORTB.4=1) then
    goto Debounce                                ' Button still pressed?
  endif  
  Goto Progstart

[RuudNL]

I forgot to mention that there are resistors to ground (to keep the input 'low' when no button is pressed) and that the buttons switch to the +5 Volts.

[HenrikOlsson]

16384+12 seems correct for (inverted) 31250 but should it BE inverted and why 16384+3313? (I don't know MIDI...)

Can you do a standard baudrate like 9600 and verify that data is coming out by using a terminal program?

The 16F628 does have UART so HSEROUT will work with it. I'd try that but you might need to invert the signal externally.

[RuudNL]

The 16384+12 is correct, I have used that before.
The calculation is: (1.000.000/Baudrate) - 20 , so 1.000.000 / 31250 = 32 -20 = 12.
For inverted output set bit 14, = 16384.
But even with a different baudrate I don't get any output.

I did a quick test to trace the problem.
With this code, nothing 'toggles':

Progstart: 
  if PORTB.0 = 1 then 
    Toggle PORTB.6
  endif  

Debounce:
  Pause 20                                       ' ? shorter ?
  If PORTB.0=1 then
    goto Debounce                                ' Button still pressed?
  endif  
  Goto Progstart

So I suspect the problem is in the line (and similar lines)

  If PORTB.0=1 then

Although I don't see what could be wrong with this...

[Demon]

If I don't touch programming for a while, I start with blinking a LED to make sure I have the basics working right (config, circuit, programming, etc).

[Demon]

...
If PORTB.0=1
...

You're assuming it can read port B properly.

I'd start even easier, just blink a LED, nothing else, then build from that.

[RuudNL]

So nobody can spot a mistake in my sample code?
Strange, because this line is handled correctly:

If (PORTB.0=1) or (PORTB.1=1) or (PORTB.2=1) or (PORTB.3=1) or (PORTB.4=1) then
.....

[Demon]

I pulled out one of my old 16F628 programs from mothballs, only thing I notice, you have no CONFIG statements.


EDIT: I used this with DEFINE OSC 20

@ __CONFIG _HS_OSC & _WDT_OFF & _PWRTE_ON & _BODEN_ON & _MCLRE_ON & _LVP_OFF & _CP_OFF

[RuudNL]

I set the config parameters in the programmer (as usual).
The values you mentioned are the defaults in my programmer, except the HS mode, that I set manually.
The point is that everything (almost) works.
If I create a loop that does nothing else than: serout2 xxx, delay 1000, I get MIDI information every second.
My main suspect is that the switch(es) are not read correctly in: if PORTB.x =1 then ...

[Demon]

Is this the "read modify write" problem?
(I have to look that up whenever I encounter weird problems)

[Demon]

I set the config parameters in the programmer (as usual)...

What if you set them in the program? Maybe something is wonky with your programmer config. (total wild guess, just eliminating stuff)

[Demon]

...If I create a loop that does nothing else than: serout2 xxx, delay 1000, I get MIDI information every second.
My main suspect is that the switch(es) are not read correctly in: if PORTB.x =1 then ...

Blinking a LED confirms if your timing is running at the speed you think it's running at.

I usually go for LED 1/2 second OFF, 1/2 second ON, just to know my OSC is running as it's supposed to.

EDIT: Hm, yeah, but you're getting a SEROUT every second already, so not sure what else to check.

[RuudNL]

I never had problems setting the config parameters in the programmer, but I will try that anyway...
I have a feeling that the problem is in the line:

  if PORTB.0 = 1 then   '<---- this line?
    Serout2 PORTB.7, 16384+12, [144, 44, 127]    ' Rewind
  endif

The strange thing is that the switch status IS correctly read in this part:

Debounce:
  Pause 20                                          ' ? shorter ?
  If (PORTB.0=1) or (PORTB.1=1) or (PORTB.2=1) or (PORTB.3=1) or (PORTB.4=1) then
    PORTB.6 = 1                                   ' ADDED TO CHECK!! 
    goto Debounce                                ' Button still pressed?
  else
    PORTB.6 = 0                                   ' ADDED TO CHECK!!
  endif  
  Goto Progstart

So PORTB.6 is high as long as a button is pressed.

And a loop Serout xxx/ Pause 1000 spits out a burst of MIDI data every second, so it doesn't look it is a config problem.

[Ioannis]

Instead of this

  if PORTB.0 = 1 then   '<---- this line?
    Serout2 PORTB.7, 16384+12, [144, 44, 127]    ' Rewind
  endif

try this

  if PORTB.0 = 1 then   '<---- this line?
    High LED
    Pause 100
    Low LED    ' Rewind
  endif

Set LED to a Port and see if it blinks.

Ioannis

[RuudNL]

It doesn't. I tried already:

  If PORTB.0 = 1 then
    PORTB.6 = 1
  else
    PORTB.6 = 0
    ' and loop...

PORTB.6 never gets high!

I can't wrap my head around it...
In the past I've written considerably more complicated code, usually with success.
I think I'll sleep on it and try again from scratch tomorrow!
Thank you everyone for your thoughts!

[Ioannis]

Then fried PIC maybe?

Ioannis

[RuudNL]

I doubt it... It is a brandnew one!
What I find extremely strange, is that it seems the status of PORTB.x is not read in:

if PORTB.0 = 1 then 
    Serout2 PORTB.7, 16384+12, [144, 44, 127]    ' Rewind
  endif

But IS read in:

Debounce:
  Pause 20                                          ' ? shorter ?
  If (PORTB.0=1) or (PORTB.1=1) or (PORTB.2=1) or (PORTB.3=1) or (PORTB.4=1) then
    PORTB.6 = 1                                   ' ADDED TO CHECK!! 
    goto Debounce                                ' Button still pressed?
  else
    PORTB.6 = 0                                   ' ADDED TO CHECK!!
  endif  
  Goto Progstart

If it was a faulty PIC, this wouldn't work in both cases.

[Ioannis]

Is it possible that you have high capacitance on the port B pins?

Try to add pause 10 every after command and see how it goes.

Ioannis

[Demon]

Defective breadboard?

[RuudNL]

In the meantime there is some progress:

CMCON =  7                                       ' Digital mode
DEFINE OSC 20                                    ' 20 MHZ OSC.                                                                      
TRISB= %00111111                                 ' PORTB 6/7=Output 0..5=Input

Progstart: 
  if (PORTB & 1) = 1 then 
    Serout2 PORTB.7, 16384+12, [144, 44, 127]    ' Rewind
  endif  
  if (PORTB & 2) = 2 then 
    Serout2 PORTB.7, 16384+12, [144, 46, 127]    ' Fast Fwd.
  endif  
  if (PORTB & 4) = 4 then 
    Serout2 PORTB.7, 16384+12, [144, 48, 127]    ' Stop  
  endif  
  if (PORTB & 8) = 8 then 
    Serout2 PORTB.7, 16384+12, [144, 50, 127]    ' Play  
  endif  
  if (PORTB & 16) = 16 then 
    Serout2 PORTB.7, 16384+12, [144, 52, 127]    ' Record
  endif  

Debounce:
  Pause 100                                      ' ? shorter ?
  If (PORTB.0=1) or (PORTB.1=1) or (PORTB.2=1) or (PORTB.3=1) or (PORTB.4=1) then
       goto Debounce                                ' Button still pressed?
  endif  
  Goto Progstart

This works, as long as I comment out these lines:

 '  If (PORTB.0=1) or (PORTB.1=1) or (PORTB.2=1) or (PORTB.3=1) or (PORTB.4=1) then
 '     goto Debounce                                ' Button still pressed?
 '  endif

The idea is of course to prevent that the same data is sent multiple times, so I want to wait until a button is released.
But the these lines seem to avoid that PORTB is read again.

[RuudNL]

It seems the problem is solved. (Although I still don't understand why my first attempt didn't work...)
Now I use BUTTON as included in Picbasic. I don't like all the labels, but at least this works now!

'* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
'* MIDI Remote for Reaper            20 MHz resonator (HS)           *
'* PIC16F628                                                         *
'* PORTB.0 = Rewind                                                  * 
'* PORTB.1 = FastFwd.                                                *
'* PORTB.2 = Stop                                                    *
'* PORTB.3 = Play                                                    *
'* PORTB.4 = Record                                                  *
'* PORTB.7 = Output                                                  *
'* Version 1.0                       03 March 2024                   *
'* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
        
CMCON =  7                                       ' Digital mode
DEFINE OSC 20                                    ' 20 MHZ OSC.       
'DEFINE BUTTON_PAUSE 50                          ' Is this needed ?                                     
TRISB= %00111111                                 ' PORTB 6..7=Output 0..5=Input

BTN1 var Byte                                    ' Button variables for internal use 
BTN2 var byte
BTN3 var byte
BTN4 var byte
BTN5 var byte

BTN1 = 0                                         ' Initialize button variables
BTN2 = 0
BTN3 = 0
BTN4 = 0
BTN5 = 0

Progstart: 
  BUTTON PORTB.0, 1, 255, 0 , BTN1, 0 , But2
  Serout2 PORTB.7, 16384+12, [144, 44, 127]      ' Rewind
But2:
  BUTTON PORTB.1, 1, 255, 0 , BTN2, 0 , But3
  Serout2 PORTB.7, 16384+12, [144, 46, 127]      ' Fast Fwd.
But3:  
  BUTTON PORTB.2, 1, 255, 0 , BTN3, 0 , But4
  Serout2 PORTB.7, 16384+12, [144, 48, 127]      ' Stop  
But4:  
  BUTTON PORTB.3, 1, 255, 0 , BTN4, 0 , But5
  Serout2 PORTB.7, 16384+12, [144, 50, 127]      ' Play  
But5:
  BUTTON PORTB.4, 1, 255, 0 , BTN5, 0 , ProgStart
  Serout2 PORTB.7, 16384+12, [144, 52, 127]      ' Record
Goto Progstart

The moral: never try to reinvent the wheel!

[HenrikOlsson]

I think the first version should work - but do so quite unreliably.
The reason: If the button being pressed happens to FIRST be checked in the debounce routine the code will be stuck there until the button is released and no action will be taken.
One would think that if you have played with this for some time it would at least sometimes be detected at the "correct" place before falling into the debounce though.

It would probably be a better idea to GOSUB the debounce routine after the SEROUT2 statement or simply:

  if (PORTB & 1) = 1 then 
    Serout2 PORTB.7, 16384+12, [144, 44, 127]    ' Rewind
     WHILE PORTB.1 : WEND
     PAUSE 10  ' Or whatever
  endif

[Ioannis]

Henrik, I think this does not explain why code in post #4 also does not work as the RuudNL says.

Ioannis

[HenrikOlsson]

You mean this:

Progstart: 
  if PORTB.0 = 1 then 
    Toggle PORTB.6
  endif  

Debounce:
  Pause 20                                       ' ? shorter ?
  If PORTB.0=1 then
    goto Debounce                                ' Button still pressed?
  endif  
  Goto Progstart

If so then it's the same potential issue. The PIC runs thru this short program in a couple of microseconds (lets say 20), except for the PAUSE 20 where it spends 99.9% of its time. The likelyhood of the button being pressed during this time and therefor NOT cause the output to toggle is 999 in 1. In the initial code the PAUSE was even longer further decreasing the chanse of the button being polled outside of the debounce routine. Run the code, press the button a few thousand times it "should" toggle the output at least once.

That's my theory and I'm sticking to it until someone comes up with a better one :-)

/Henrik.

[Demon]

Very good reasoning.
😎

[Demon]

What happens if you just sit on the button?

[HenrikOlsson]

Unless you happen to sit down at EXACTLY the right time your ass will be stuck in the debounce loop.

[Ioannis]

Indeed Henrik. You are absolutely right!

Now I recall I had the same issue once and instead of loose my time trying to find the strange error, i went off to a state machine logic and kept my sanity!

Ioannis