This past weekend I continued working on my Data Acquisition Box, now renamed to the Scrappy Science Caddy (inspired by The Venture Brother’s character Henry Killinger’s Magic Murder Bag https://www.youtube.com/watch?v=hNqZ7qsWpJc). In order to connect the LCD, MCP3008 A/D Chip, and all the various buttons to the Raspberry Pi I reused an old IDE cable, which if you pull apart just right, provides a perfect connection to the GPIO pins. This is the third or fourth time I’ve done this and have had success; but there’s also a couple pitfalls and issues to avoid.
Wire to the Notch, nothing more
In the image is a close up of one of the individual IDE pins removed from the header/connector, the red arrow marks a critical notch. This little bump is what “locks” the pin into the connector, so you don’t want to get solder past this point, otherwise the pin will not click/lock into the header and you can end up with a bad connection or a pin that likes to fall out of the connector.
Use Flux & Shrink Wrap
This goes with the previous statement, in order to solder effectively and get a good joint you’ll want to use solder flux, otherwise the “weld” to the pin could be pretty fragile. Also, the flux helps keep the solder from going past that critical bump. Finally, use shrink tubing to protect the joint and avoid contact with adjacent pins. When applying the tubing also make sure it doesn’t extend too far down and impede the pin from seating in the header/connector properly.
Avoid Bending unless Reinforced
The pins are not super durable so you want to avoid bending and flexing the pin or the joint, otherwise a break may occur and you won’t get a good (or any) connection. One way to do this is place some glue (from a hot glue gun) on the pins to hold them into the connector, apply enough to cover the entire pin, this will make it almost impossible to make changes on the connector, but it’ll make it sturdy enough so that any flexing happens in the attached wire rather than the pin and solder joint.
With these few notes and tips, as well as learning some of these lessons the hard way; I’ve good success reusing IDE connectors with the Raspberry Pi.