On Thu, Sep 29, 2011 at 11:19 AM, Harold Hallikainen <harold@hallikainen.or=
g
> wrote:

> I built a "logic analyzer" many years ago. I used the printer port on a
> Cromemco CP/M computer as the logic inputs. I watched for a change in the
> byte I read from the port, then saved the new value to memory and bumped =
a
> pointer. Once I had finished a capture, I printed out all the data in
> binary, one byte per line. I used this to reverse engineer the serial bus
> on a Commodore 1541 floppy disk drive.
>
> For your application, I think it'd be easier to add external RAM to use
> during capture, then send the data after capture. I've got a project usin=
g
> a 1MB static RAM that's easy to interface to. I used it on a PIC24 which
> did not have the parallel master port, so I bit banged it. On the PIC32,
> you could use the PMP for a fair amount of the work (though you'd have to
> manually control higher address lines).
>
> Here's some of my UsbTask code from a project:
>
>    if(!USBHandleBusy(USBGenericOutHandle)){    // If it's safe to look at
> the receive buffer
>      if(count=3DUSBHandleGetLength(USBGenericOutHandle)){    // if there'=
s
> something in the receive buffer
>        if(count<=3DpUsbRxFifo->BytesFree){   // we have room in the fifo
>          index=3D0;
>          while(count--){
>            PutFifo(pUsbRxFifo,OUTPacket[index++]);     // get data from
> usb buffer to fifo
>          }
>          USBGenericOutHandle =3D
> USBGenRead(USBGEN_EP_NUM,(BYTE*)&OUTPacket,USBGEN_EP_SIZE); //
> ok to read more
>        }// endif we had room
>      }// endif there was something there
>    }// endif not busy
>    if(!USBHandleBusy(USBGenericInHandle)){ // 0 if ok to transmit
>      if(count=3DpUsbTxFifo->BytesInBuf){  // we have something to send
>        if(count>=3Dsizeof(INPacket)){
>          count=3Dsizeof(INPacket);         // limit how many bytes we sen=
d
> to size of output buffer
>        }
>        index=3D0;
>        NumBytes=3Dcount;       // remember how many bytes we're sending
>        while(count--){
>          INPacket[index++]=3DGetFifo(pUsbTxFifo);  // fill the transmit
> buffer from the fifo
>        }
>        USBGenericInHandle =3D
> USBGenWrite(USBGEN_EP_NUM,(BYTE*)&INPacket,NumBytes); // send the
> bytes
>      }
>    }
>
>
Thanks for the reply. Your code is pretty similar to my code.
--=20
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