After a short period of thinking how a fast sample rate could be achived and gathering most chips needed I started to check on the USB communication.
Using the Microchips PICDEM FS USB MCHPUSB Generic Driver Demo firmware with a VB 2008 program got me started.
The main controller is a PIC18F4550 because of the USB capacities and the number of ports. All the data is sampled into a static memory chip, clocked by the PIC. Via two 12 bit ripple counters the address is set and two 74HC244 CMOS logics open the 16 bit data flow into the RAM chip. After a complete read burst the PIC is used to read al data from the memory chip and send it over the USB to the PC.
If this function works I wil start the extention for the oscilloscope, reading 8 bit analog values via three TDA8703 chips.
See the drawing below
Rick
