USB, PIC18F2550 and VB

[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?