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I was wondering if I could ask you for some help, i'm playing with a pic USB interface tutorial, where an unsigned char is written to the firmware from a c++ application.

C++
ProcessIO(void)
{
if((USBDeviceState < CONFIGURED_STATE)||(USBSuspendControl==1)) return;
       if(!HIDRxHandleBusy(USBOutHandle))                                    
           {
             switch(RecievedDataBuffer[0])
              {
                 case 0x01:          //do something          
           break;
                 case 0x02:          //do something
           break;
              }
	USBOutHandle = HIDRxPacket(HID_EP,(BYTE*)&ReceivedDataBuffer,64);
    }
} 


The problem is the RecievedDataBuffer[0] is tested through switch statements. I have about 60 different commands to be sent VIA usb to the firmware from a c++ application (the code I am talking about is the firmware for a PIC 18F), the only difference being the hexi code stored in the DataRecievedBuffer[0]. So instead of writing 60 switch statements, only with different hex values, I would just like to replace the switch statement above to the code below:

MIDL
j = ReceivedDataBuffer[0];             //unsigned char j = recieved data
        upper_nibble = j & 0x0f0;              //bit mask lower bits
        PORTB = upper_nibble;
        DelayMs(100);

        RB1 = 1;                               //pulse enable line
        DelayMs(100);
        RB1 = 0;
        DelayMs(100);

        PORTB = 0x00;
        k = (j << 4) | (j >> 4);               //swap nibbles
        lower_nibble = k & 0x0f0;              //again bit mask to leave the lower nibble         PORTB = lower_nibble;

        DelayMs(100);
        RB1 = 1;                               //pulse enable and reset
        DelayMs(100);
        RB1 = 0;
        DelayMs(100);
        PORTB = 0x00;                          //clear port



So i'm looking to send each command recieved in the buffer to the pins of my PIC, but the program crashes...Do you have any suggestion of how I could fix this?

OK...I think this is pretty unclear...At the moment, there is a switch statement between:
VB
if(!HIDRxHandleBusy(USBOutHandle))

...and
MIDL
USBOutHandle = HIDRxPacket(HID_EP,(BYTE*)&amp;ReceivedDataBuffer,64);

All i would like to do is replace this switch statement with the second block of code down from the top of this page, but it seems like when ever I try to put a statement other than the switch statement above, the system is completly unresponsive. I don't have an in-circuit degugger so I'm doing this blindly. I was just wondering if somebody could see something fundamentally wrong in replacing:
MIDL
switch(RecievedDataBuffer[0])

with something like:
C++
If( (RecievedDataBuffer[0]) = 0x02)

Thanks

Martyn
Posted
Updated 28-Jul-11 1:28am
v4
Comments
Richard MacCutchan 28-Jul-11 5:04am    
Your question makes no sense; what does this code have to do with a switch statement?
kutalinelucas 28-Jul-11 5:16am    
Sorry, I guess formatting doesn't work on the submit comment part so I can't illustrate my point with code, and I was given a row yesterday for submitting a follow up question in the 'solution' bit....if you look at the top code, a hex value is recieved in unsigned char RecievedDataBuffer[0]. Then the program enters a large switch statement...ie switch(RecievedDataBuffer[0])...case 0x01: etc....As I have 60-odd possible hex values to be sent to the firmware, and the only difference being the hex value, I would like to replace a massive switch statement with the bottom code, which simply assigns the contents of 'RecievedDataBuffer' to 'j', so i can break the hex into nibbles and send to portB.
Richard MacCutchan 28-Jul-11 5:49am    
1. You can use the "Improve Question" button to change your original query.
2. I still don't understand your problem, you want to remove the switch block and replace it with different code; OK go ahead if that will solve the issue. You also say that the program crashes but not where it crashes or what the circumstances are. Are you able to use a debugger to trace the program?
3. When replying please use the "Reply" button, not "Add comment".
kutalinelucas 28-Jul-11 6:30am    
Hi Richard. I updated the question. The problem is I CAN'T replace the switch statement with the different code. I just thought the if statement above would be a direct replacement for the switch statement that works. Again I can't dunug unfortunatly so i'm pretty stuck.
kutalinelucas 28-Jul-11 6:42am    
I'm an idiot...I just left out a '=' in the if statement...hopefully it'll be ok now...thanks

1 solution

its so easy

If( (RecievedDataBuffer[0]) = 0x02)
{
}
else If( (RecievedDataBuffer[0]) = 0x01)
{
}
else
{
cout << "gone to hell";
}
 
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