Using Ribbon Cables on the SX48/52 Proto Board
LoopyByteloose
Posts: 12,537
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
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
Comments
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
·
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
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
·
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