Using Ribbon Cables on the SX48/52 Proto Board

LoopyByteloose

I am trying to set up ribbon cables as my preferred interface.

I see that old floppy disk drives made all the odd pins go to Ground.·
Is there any merit to doing so?·

In other words, will it create a ground plane or some form of protection from RFI and EMI?

It looks like I can use a 20 pin 90degree male plug to get Port RA and power, but no alternative Ground wires.

Also It looks like I can use Ports RC and RB [noparse][[/noparse]with a 32 pin 90 degree male plug] either as doubled·I/O alone
-or- if I move inboard on row, I can get power and interface 50% ·with the lower SOIB [noparse][[/noparse]this may be useful for an RS485 driver as one side seem to be entirely·RS-485 and the other side is TTL.

Any comments appreciated.·

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G. Herzog in Taiwan

Post Edited (Kramer) : 9/21/2005 2:23:58 PM GMT

Bean

It prevents cross-talk between the signals.
Bean.

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"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
Available soon!! Video overlay(OSD) module...

"I'm a man, but I can change, if I have to, I guess"
Red Green
·

LoopyByteloose

Thanks Bean,
The problem is that I really don't think I can easily provide the grounds as the board stands, so cross talk may have to live or die on its own.
I can modify the board and get alternating grounds to maybe 3 of the ports, but certainly not to all. RC will require me cutting the Vdd line on one pin.

Why bother?
I think that ribbon cables are much less trouble for proto-typing than rigid connectors, especially as the pin count causes friction to become a problem. [noparse][[/noparse]I am forever bending 40 Pin DIPs.]

Individual wires are tedious and problematic in their own right.

So, I guess I am trying to say that in the next generation of proto-boards.... give a bit of room for ribbon cables.
I imagine at the higher speeds the crosstalk becomes worse.
And, 40PIN DIP will never be as popular.

If Parallax were to provide RA with a 16 pin and RC and RB with a 32 pin, that might be enough. One could always build a split cable on the 32 pin to send RC to one board and RB to another.

RE has the reset button next to it and may be a problem to configure

RD is next to the microprocessor and a ribbon cable might interfer with cooling and just melt.

I really like the fact that both DIP8's and SOIC8's are taking nearly the same footprint - smart thinking.

Admittedly, these suggestions might cause the board to become a little bigger. . .
but one might shift the reset nearer to the LED and shift the X-2 XTAL and the SX-48/58 closer to the bottom left corner. Then keeping RE and RD in the same place, but with a row of grounds and shifting all else 0.2 to the right might get you clearances on the same size board.

Food for thought. Bye.

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G. Herzog in Taiwan

Post Edited (Kramer) : 9/22/2005 9:47:57 AM GMT

Bean

The signal doesn't have to be ground, it can be Vdd, or even a signal (output) that doesn't change state very often.
Try to intermix fast and slow signals. Expecially fast inputs and slow outputs.
The worst option is two fast inputs next to each other.
Bean.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
Available soon!! Video overlay(OSD) module...

"I'm a man, but I can change, if I have to, I guess"
Red Green
·

LoopyByteloose

Thanks again Bean, a lot more flexiblity.

I ran out to buy a 32pin ribbon cable only to find they don't make them -34 pins or 30 pins. More learning curve.

So it seems that if Parallax ever designs a board with ribbon cables, 20 pin cables or 40 pin cables would be optimal [noparse][[/noparse]the 40s would have half the leads providing Vss or Vdd]

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G. Herzog in Taiwan