Hi! I have a big FIFO chip covered by dust, that I'd like to finally use. The most useful application I'm imagining for it is to finally make myself a logic analyzer. This FIFO (Texas Instruments SN74V3690-6PEU) is a 3.3V device, but has 5V tolerant inputs. "Great!" I thought. What I'm asking you is: should I connect the probes (just a header cable) directly to the FIFO, or should I use an high speed buffer inbetween? Consider that the chip is specced at 166MHz. Moreover, what is the cheapest way to produce a variable clock speed up to 166MHz (and possibly beyond, for other applications)? A PLL? Any chip you may suggest me? Thanks! TPM
FIFO as a Logic Analyzer; Clock synthesizer
Started by ●April 21, 2005
Reply by ●April 21, 20052005-04-21
nospam@nospam.com wrote:> Hi! > I have a big FIFO chip covered by dust, that I'd like to finally use. > The most useful application I'm imagining for it is to finally make > myself a logic analyzer. This FIFO (Texas Instruments SN74V3690-6PEU) > is a 3.3V device, but has 5V tolerant inputs. "Great!" I thought. > > What I'm asking you is: should I connect the probes (just a header > cable) directly to the FIFO, or should I use an high speed buffer > inbetween? Consider that the chip is specced at 166MHz. > > Moreover, what is the cheapest way to produce a variable clock > speed up to 166MHz (and possibly beyond, for other applications)? > A PLL? Any chip you may suggest me? > > Thanks! > TPM >Why not a CPLD or FPGA. And do your own frequency synthesizer using an accumulator. For high speed accumulator, use pipeline methodology. Laurent www.amontec.com
Reply by ●April 21, 20052005-04-21
Re the clock: If you're going to put a processor in the project that's I2C capable, use the AD9834 to divide down a nice high frequency oscillator to any frequency you want. Analog Devices has a web tool to help you get the hang of programming it, and it's a GREAT chip! http://www.analog.com/Analog_Root/static/techSupport/designTools/interactiveTools/ad98334/ad9834.html Good luck! Len
Reply by ●April 21, 20052005-04-21
Re the clock: If you're going to put a processor in the project that's I2C capable, use the AD9834 to divide down a nice high frequency oscillator to any frequency you want. Analog Devices has a web tool to help you get the hang of programming it, and it's a GREAT chip! http://www.analog.com/Analog_Root/static/techSupport/designTools/interactiveTools/ad98334/ad9834.html Good luck! Len
Reply by ●April 21, 20052005-04-21
nospam@nospam.com wrote:> Hi! > I have a big FIFO chip covered by dust, that I'd like to finally use. > The most useful application I'm imagining for it is to finally make > myself a logic analyzer. This FIFO (Texas Instruments SN74V3690-6PEU) > is a 3.3V device, but has 5V tolerant inputs. "Great!" I thought. > > What I'm asking you is: should I connect the probes (just a header > cable) directly to the FIFO, or should I use an high speed buffer > inbetween? Consider that the chip is specced at 166MHz. > > Moreover, what is the cheapest way to produce a variable clock > speed up to 166MHz (and possibly beyond, for other applications)? > A PLL? Any chip you may suggest me? > > Thanks! > TPM
Reply by ●April 21, 20052005-04-21
TPM wrote:> Moreover, what is the cheapest way to produce a variable clock speed > up to 166MHz (and possibly beyond, for other applications)? A PLL? > Any chip you may suggest me?Larry Amontec wrote:> Why not a CPLD or FPGA. And do your own frequency synthesizer using an > accumulator. For high speed accumulator, use pipeline methodology.Leonard Gabrielson wrote:> Re the clock: If you're going to put a processor in the project that's > I2C capable, use the AD9834 to divide down a nice high frequency > oscillator to any frequency you want.Both suggestions are DDS (Direct Digital Synthesis). That's great for a lot of things but not so great for producing high frequency square waves. For that, you're much better off with a PLL. You might try the Cypress CY22150 or CY22393/4/5 programmable clocks. They're fairly inexpensive, and available from Digikey. http://tinyurl.com/923g2 http://tinyurl.com/dyden For the CY22150, they have a nifty little "Licorice" demo board (CY30700), that only costs $20. Eric