USB, PIC18F2550 and VB

[Tissy]

I think i have 75% of my code working except for the following:

The main purpose of the PIC is to look for button pushes on the PIC inputs and perform a specific task depending on which buttons are pushed. However, when a VB application is loaded, any of the variables which are set in the VB program and sent to the PIC via USB are then used by the PIC for timing functions.

Its basically a programmable timer, where the VB program is being used to set the timing variables.

However, the PIC code at the moment is ignoring the button inputs until you send the data from VB to the PIC.

So, push a button, nothing happens. Keep a button held AND send data from VB to the PIC and it recognises the button push. Push button again on its own and nothing happens, until of course you hold the button down AND send data again.

Can anyone figure out whats going wrong by looking at this code.

DEFINE OSC 20          
DEFINE LOADER_USED 1


' ---------- [ I/O Definition ] ----------
TRISA = %11111111       ' Set PORTA to all input
TRISB = %10000001       ' Set PORTB (0)INPUT (1-5)OUTPUTS
TRISC = %00000111       ' Set PORTC (0-2 input) rest Outputs
PORTB = 0


' ----- [ Variable Definitions ] ----------
Loop                Var Byte
MaskSwitch          Var Byte
DelayOut            Var Byte
Seconds             Var byte ' 0-59
SecondsDelay        Var byte
Minutes             Var byte ' 0-59
MinutesDelay        Var byte
Hours               Var byte ' 0-23
HoursDelay          Var byte
SecondsDelayOut     Var Byte
MinutesDelayOut     Var Byte
HoursDelayOut       Var Byte


' the USB buffer...
USBBuffer           Var Byte[USBBufferSizeMax] 
USBBufferCount      Var Byte

USBBufferSizeMax    con 32  ' maximum buffer size
USBBufferSizeTX     con 32  ' input 
USBBufferSizeRX     con 32  ' output


' ----- [ Variable Constants ] ----------
HoursDelay = 0
MinutesDelay = 2 '1 To 60
SecondsDelay = 0 '1 To 60


' ---------- [ System Inputs ] ----------
SW1         Var PORTC.0
SW2         Var PORTC.1


' ---------- [ System Outputs ] ----------
Red         VAR PORTB.1     ' All LEDs connected
                            ' between RC pins and
                            ' ground via resistor

' ************************************************************
' *                   Main Program Section                   *
' * main program loop - remember, you must keep the USB      *
' * connection alive with a call to USBService every couple  *
' * of milliseconds or so...                                 *
' ************************************************************

usbinit ' initialise USB...

Main:
        Gosub DoUSBIN
        Gosub DoUSBoUT

    MaskSwitch=PORTC & $07
        Select Case MaskSwitch
          Case 1 '%00000001
            If SW1=1 Then Gosub Procedure_SW1
            If SW1=0 THEN
            EndIf 

          Case 2 '%00000010
            If SW2=1 Then Gosub Procedure_SW2
            If SW2=0 THEN 
            EndIf 

          Case Else
            Goto Main
    End Select
Goto Main


' ************************************************************
' * receive data from the USB bus                            *
' ************************************************************
DoUSBIn:
   USBBufferCount = USBBufferSizeRX              ' RX buffer size
   USBService                                    ' keep connection alive
   USBIn 1, USBBuffer, USBBufferCount, DoUSBIn   ' read data, if available
Return

    
' ************************************************************
' * wait for USB interface to attach                         *
' ************************************************************
DoUSBOut:
   USBBufferCount = USBBufferSizeTX              ' TX buffer size
   USBService                                    ' keep connection alive
   USBOut 1, USBBuffer, USBBufferCount, DoUSBOut ' if bus available, transmit data
Return

   
Procedure_SW1:
'Do Something
Return


Procedure_SW2:
' Do Something Else
Return

I'm guessing once you Gosub DoUSBIn this keeps looping until some data is received. Is there a way to set it so that if no data is exchanged, it comes out of the loop. ie perform primary function, but always look at USB for any possible data, if none continue with primary function. As the need to send data from VB to the PIC is minimal. ie once the timing variables are sent, the need to change them from time to time is minimal. If i comment out the Gosub DoUSBIn line, the primary function of the PIC works fine.

Many thanks.

[Tissy]

I have found that if you put the Gosub DoUSBin routine at the beginning of the code (ie before the Main: routine) then the PIC waits for data transfer and when you send the variables from VB, then it continues with the PICs primary function and uses the variables you sent correctly. This is fine if it is a one of function when you power up the PIC. However, it is not, the PIC will always be powered-up.

So, if you want to change the variables, then you need to reset the PIC and resend them again using USB.

I want to get away from using a button for 'programming mode', so in otherwords it doesn't matter at what stage you send the variables from VB without there being a need for user intervention on the PIC side.

I need to get it out of the loop !!

Steve

[Bruce]

Have you tried something like incrementing a variable in the DoUSBin loop, and exiting once it reaches a certain value?

DoUSBIn:
USBBufferCount = USBBufferSizeRX ' RX buffer size
USBService ' keep connection alive
X = X + 1
PAUSEUS 5000 ' 5mS delay
IF X > ExitVal THEN JumpOut
USBIn 1, USBBuffer, USBBufferCount, DoUSBIn ' read data, if available
JumpOut:
Return

[Tissy]

Thank you so much Bruce, that has been driving me mad for weeks on end. I've been working alot on the other code and kinda working around this, but it works very well indeed now. You're right, it now exits from the loop and back to the main routine. You're a genius !!

Cheers again.

Steve

[Tissy]

Having now got that piece of code working it has presented this:

If you remove power to the PIC and then reconnect, it of course first looks for the USB and data as per the Gosub DoUSBin etc. As at this stage the USB databuffers are empty, ie no data being sent, it stores the EEPROM variables as 0, instead of retaining the previously stored numbers.

I have come up with this, what i think, long winded solution.

Where by the top three lines of code read:

Main:
        Gosub DoUSBIN
        Gosub CheckData
        Gosub DoUSBoUT

And then

CheckData:
    	If USBBuffer[9] = 0 Then
            Read 1, SecondsDelayOut     ' read previously stored
            Read 3, MinutesDelayOut     ' variables from EEPROM
            Read 5, HoursDelayOut       ' before they are blanked            
    	        SecondsDelayOut = SecondsDelay
    	        MinutesDelayOut = MinutesDelay
    	        HoursDelayOut = HoursDelay
            Return  
        Else 
	        SecondsDelay = USBBuffer[11]
	        MinutesDelay = USBBuffer[13]
	        HoursDelay = USBBuffer[15]

	        Write 1, SecondsDelay
	        Write 3, MinutesDelay
	        Write 5, Hoursdelay
        EndIf
Return

Obvioulsy in VB when i write the data again, i set BufferOut(10) = 1 to write the new variables.

Is this the easiest way?