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Passing address & databus of micrcontroller on Ribbon Cable

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clutter4

New Member
I am looking for opinions on the following matter....

I am designing a system where a keypad & LCD display assembly would best be remote from the main PCB. By remote I mean separated by 400mm typically. in this case it would mean clocking in control & data for the display unit along (eg..) a ribbon cable from the micrcontroller on the main PCB... this using the inherent read/write processor timescales. In my case, the RD & WR signals would be approx 450nS wide. The LCD display interface is databus & RD, WR & CS.

What I am trying to get an idea of is .... if anyone has any experience of driving microcontroller bus data along ribbon like this to a target device.... Could it be a bad idea in the sense that the integrity of the databus signals, together with RD, WR & CS signals are likely to be compromised or degraded over a medium like ribbon that is less than PCB perfect, and the system then not work well.



Thank you.
 

crutschow

Well-Known Member
Most Helpful Member
Ribbon cables have well controlled characteristics. Sending a 450nS signal down 400mm of ribbon should be ok. For best results you should run a ground connection between each set of signal lines (every other ribbon wire is a ground) to give a short return path for the signals and give the best signal integrity.

Edit: The ground wires should be terminated in ground planes at both ends of the cable.
 
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clutter4

New Member
thank you gents for those replies..

The MCU will run at a clock of 12Mhz. From that, I calculate the RD & WR widths to be about 450nS.... I have had other suggestions like.... use of diff line transceivers to drive the signal lines... or... to consider I2C serial.


regards.
 

3v0

Coop Build Coordinator
Forum Supporter
Passing address & databus of micrcontroller on Ribbon Cable
On microprocessor the data and address buses are brought out to the pins to connect to memory. Most microcontrollers uses internal memory and have no need to connect the data or address buses to the pins. Most of the pins are connected to IO devices that connect to the data and address bus.
 
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