Actually, I forgot to mention that these RAMS were cascadable. I actually had two in cascade to allow storing 512k samples per pin on each of 9 pins per memory. And I had a total of 36 channels. Eight Dual Port RAMS total. Regards, Jim > -------- Original Message -------- > Subject: Re: [PIC] PIC32 USB - for logic analyzer > From: V G > Date: Thu, September 29, 2011 12:17 pm > To: "Microcontroller discussion list - Public." >=20 >=20 > On Thu, Sep 29, 2011 at 12:48 PM, Mark Rages wrote: >=20 > > On Thu, Sep 29, 2011 at 10:29 AM, wrote: > > > > > > I built a logic analyzer many years ago that used an oscillator that > > > would increment the address counter > > > of some dual port cache RAMS. You could capture using one port of t= he > > > ram chip, and output the data on the > > > other port. The dual port rams were from Cypress IIRC, and I believ= e > > > they were 128K x 9. I used the 9th > > > bit as a trigger capture bit. After the capture, I would then send t= he > > > captured data out to the PC for > > > display. It worked well. You might try looking at some of these RA= M > > > chips. Again, IIRC, they would work > > > up to about 60 Mhz or so. > > > > > > > Microchip has some serial RAMs that do this. Just keep clocking them > > and they store a bit with each clock. Design here: > > http://dangerousprototypes.com/docs/Logic_Shrimp_design_overview > > > > > The only problem I have with these is that 256K samples isn't enough. I c= an > store 250k samples on the PIC32 RAM itself if I wanted to. I either need = to > stream it to the host on the fly, or need some cheap DRAMs. > --=20 > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .