Minimal design for xilinx?

They will be *very* simple. If you want PC44, get at least a xc9572!

Per power pin, plus whatever is required by your regulator.

Some kind of clock. For what you want to do, make it as slow as possible. Connect it to a GCK pin. Keep in mind that a 1MHz clock input used to make your LED blink at 1Hz would take 20 of 36 macrocells for the clock divider!

I suggest you use a low-frequency RC oscillator. Look at the second circuit in "six easy pieces" on the Xilinx website. That will save you lots of counter stages. Peter Alfke

simple. If you want PC44, get at least a xc9572!

required by your regulator.

slow as possible.

Another idea is to add a footprint for a HC4060, or a HEF4060. That gives you a Xtal or RC OSC, buffer and divider chain in a low cost (35c 1+, 13c/2500), small SO16 package. Can work with crystals from 32KHz, to some MHz

If you've chosen a 9536, then low power is probably not on your radar ?.

-jg

Regulator ?

ONE led is rather too minimalist - why not a 7 segment display, and maybe a Piezo Sounder/speaker ?

-jg

I agree, you will outgrow/get bored with this board rather quickly. Why not buy a simple board? If you scan the web (ebay?) you can find some very low cost boards, see e.g

Hans

I thought xc9536 *is* PC44?

Do I need three bypass caps, or just one? Is 0.1uF ok or should I use 0.047uF?

One microcell per register bit - 1 MHz = 20 bits = 2 ^ 20

I don't know if this device has luts/flipflops like the Virtex/Spartan which can hold a 16 bit shift register in one cell. If yes, a divide by up to 16 element can be put into one cell. Dividing 1MHz downto 1 Hz takes 5 cascaded shift registers.

device has luts/flipflops like the Virtex/Spartan

I can send you a PCB for cost of postage that has:

location for 44 pin PLCC 9536/9572/9536XL/9572XL (I would recommend 9572XL for price/macrocells)

Location for xtal oscillator (1/2 size = DIP 8)

RC oscillator with 4 selectable rates

1 Pushbutton

All I/O brought out to 2x 26 pin headers

4 pin power connector (9536XL and 9572XL run fine from 2 AA batteries)

Only disadvantage for hobby assembly is that its mostly surface mount

Peter Wallace

Here is a simple design of mine:

Leon

Rather than making and then debugging your own board, go to the Xilinx website and look for the evaluation boards. Diligent sells one for $49.00 that has an xc9572 and a coolrunner on it along with power supply and a breadboard area and a few LEDs. They also sell one through xilinx that has one CPLD, plus a solderless breadboard, switches, 7 segment display and leds for $49-59. For those costs, especially if it is a one-off to get you up the learning curve, you can't beat the kits.

Yes, and then they charge another $80 for sending it to the UK.

They both are available in PC44, with compatible pinouts. The '72 has twice as much internal logic to play with.

Yes. As close to the power pins as possible.

Yes. So if you want to see logic happen in "human time", supply the chip with a slow clock that you can see the output.

As for those who say not to do it yourself, it depends on what you are trying to learn. If you want to play with Verilog or VHDL, you can do it in a simulator. If you want to see it in real hardware, buy a board. If you want to learn how to build the board, build the board! I built something just like you describe several years ago and learned quite a bit. Not at all what I expected to learn, though!

A agree with the others over the size concerns...

You're going to very quickly reach the limits of 36 macrocells....

Ben

The 95xx is a CPLD, not an FPGA. A MUCH smaller device, with VERY limited resources. Great as a very simple bus controller, peripheral decoder, or other simple piece of logic. Equivalent to maybe 100 gates, depending a lot on how you define a "gate". It is NOTHING like a Virtex, or even Spartan, except for the logo on the package. If you know what a "PLD" is, this is a bigger one, but only bigger by a small factor.

Jon

OK, fine, but even at $129-139, that is far cheaper than what it will cost to get your own board made. You'll probably spend more than half of that just on the components, then you've got to do the artwork, have a board fabricated, stuff it, and debug it (which in itself is going to be non-trivial if you havent worked with CPLDs before) before you ever get to play with your simple design. Even if your time is worth nothing, you'll come out ahead buying the eval board AND paying to have it shipped to you.

Ray Andraka wrote: (snip)

Except that he won't get any practice in board design, fabrication, stuffing, and debugging.

-- glen