I’ve mentioned my chum Mike Pelkey on previous occasions. As you may recall, Mike is the grandfather of BASE Jumping. Along with his friend, Brian Schubert, Mike made the first parachute jumps from the top of the El Capitan mountain in Yosemite National Park in 1966.
Also, as we discussed in my Pass Me My Pencil Pointer column, Mike’s grandfather’s brother, Ed Cayo, invented the Pencil Pointer product that was beloved by architects and engineers, retired on the royalties, and traveled the world to live happily ever after. But we digress…
The founder of LogiSwitch.com, Mike is a serial inventor and entrepreneur who has a long engineering career in industrial automation. LogiSwitch’s NoBounce line of ICs and switches is a result of Mike’s 40+ year career in electronic design engineering, during which he developed switch bounce solutions for automation applications (I discussed these chips in Part 6 of my 9-part mega-mini-series on The Ultimate Guide to Switch Debounce).
The reason for my wafflings here is that Mike is working on a new project that requires a 4×4 keypad, but he’s run into a bit of a glitch. In an email from a few minutes ago, Mike spake as follows:
I started a design using a 4×4 keypad from XXXXXX. I just received it today, but the keys are wobbly and unless you strike a key dead center it bends to the side and doesn’t make contact. Do you have any experience with a good source for a 4×4 keypad you would recommend?
I removed the name of the company because I don’t like to cast aspersions (my throwing arm isn’t what I used to be). To be honest, this is a bit of a poser because I haven’t used a 4×4 keypad in any of my projects for the past couple of years, so I wouldn’t know what to recommend. I asked a couple of friends, but they are in the same boat, so now I’m asking you – do you have any thoughts you’d care to share?
Like your friends (and so, I guess, I am a friend by association) I haven’t used a matrix keyboard for yonks. So I turned to that wonderful resource, Digikey. After discovering that the word “keyboard” did not yield any usable results I went with “matrix” and filtered from there. Even limiting it to 4×4 and “active and “in stock” there are still 33 different units. There are some well respected switch manufacturers in there.
Somebody must still be using matrix keyboards…
Thanks Aubrey — it’s not that we couldn’t find them — it’s selecting one that works well and doesn’t exhibit the problems Mike experienced with the one he bought from XXXXXX 🙂
If I read between the lines, Mike is looking to make a 4×4 encoder with debounce. There used to be such a device from National Semi and subsequently Fairchild, the 74C922. If I am right, Mike might find it interesting, if not well- here’s to the memories.
I’ll make sure Mike reads these comments — thanks Aubrey — Max
Actually I am designing a combination Keypad / LCD Display combo for use in our new VisiShield line of Arduino protoextender products. I bumped into the 74C922 keypad controller obsolescence problem in the process and did design my own. It is not pin compatible, but does everything the 74C922 does (only does it a bit better). We may decide to offer it among our other ICs after this project is done. The VisiShield line of peripherals will plug into any of the three banks of our 3-banked WorkBench, and uses the I2C protocol to leave all but the two Arduino I/O pins for use with the user’s prototype. Unlike the shield architecture, the VisiShield peripherals are not hidden under a stack of shields and have no height limitations..