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RDK
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Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 6:52 am

Folks....Is there any reason why an old PATA hard drive cable should not be ok to use with the Pi's GPIO pin set?.....RDK

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DougieLawson
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Re: Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 6:58 am

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Last edited by DougieLawson on Fri Sep 12, 2014 7:13 am, edited 1 time in total.
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rpdom
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Re: Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 7:10 am

No reason at all, as long as it is one of the really old cables with just 40 wires and none of the holes blocked. I use one for some of my projects. :)

The slightly newer 40 pin cables have one hole blocked in the plugs to make sure they plug in the right way round. They can be used if you are prepared to cut that pin off your GPIO connector (it's only a GND, and there are plenty of other GND pins to use).

The latest cables had 80 wires instead of 40 and several of the pins were joined together. They usually had blue connectors and you can see that the wires are very thin and there are a lot of them. Those are no use at all.

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joan
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Re: Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 7:12 am

I guess you mean a B+ with its 40 pins. The previous models had 26 pins so a floppy cable was usable.

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RDK
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Re: Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 7:23 am

Yes, I have the older style PATA cable. And, yes, it is a Raspberry Pi B+. Thanks....RDK

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pluggy
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Re: Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 7:29 am

rpdom wrote:No reason at all, as long as it is one of the really old cables with just 40 wires and none of the holes blocked. I use one for some of my projects. :)

The slightly newer 40 pin cables have one hole blocked in the plugs to make sure they plug in the right way round. They can be used if you are prepared to cut that pin off your GPIO connector (it's only a GND, and there are plenty of other GND pins to use).

The latest cables had 80 wires instead of 40 and several of the pins were joined together. They usually had blue connectors and you can see that the wires are very thin and there are a lot of them. Those are no use at all.
The blocked pins can usually be removed with a small sharp pointy implement, since they are just a plastic pin pushed into the hole. A scalpel with a pointy blade works well.

Why would a 80 connector cable make any odds ?, they were interchangeable when you used them with hard drives, the alternative lines carried ground. It was to reduce crosstalk, but the pins were connected the same way.
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rpdom
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Re: Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 7:54 am

pluggy wrote:Why would a 80 connector cable make any odds ?, they were interchangeable when you used them with hard drives, the alternative lines carried ground. It was to reduce crosstalk, but the pins were connected the same way.
Because the 80 pin plugs also joined together other GND pins (on the hard disk interface) internally, like 2, 19, 22, 24, 26, 30, and 40, which would short GPIOs 7, 8, 10, 21 and 25 to ground and 5V :shock:

http://en.wikipedia.org/wiki/Parallel_A ... tor_cables

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Burngate
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Re: Using PC Parallel HD cable for GPIO

Fri Sep 12, 2014 8:26 am

pluggy wrote:Why would a 80 connector cable make any odds ?, they were interchangeable when you used them with hard drives, the alternative lines carried ground. It was to reduce crosstalk, but the pins were connected the same way.
http://en.wikipedia.org/wiki/Parallel_A ... tor_cables
http://www.allpinouts.org/index.php/Ult ... 66/100_IDE
In the blue connector pin 34 is connected to "ground" rather than the wire, and in the grey connector pin 28 isn't connected at all - this is for "cable select"
Also, in each connector, all the interleaved wires are connected together, and also to pins 2, 19, 22, 24, 26, 30, & 40. This will connect 5v (pin 2) to GPIOs 10, 25, 8, 7, & 21 - which would break those if it weren't also connected to ground on pin 30!

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