My keypad came in a package with hardly any information. Take your keypad an examine the bottom aspect for soldering pads. 8 pin right-angle header and matching female header for the keypad.They sell for over $10-15 each online, but, again, I picked up 10 of these at my local electronics shop for $1.50 each. You can probably get away with ceramic if you have them already. I got a handful at my local electronics shop for $0.95 each. You can pick them up from or for around $5. Optional These parts aren't necessary for you to figure out how it works, but this instructable shows several different ways to connect this keypad and read data from it, so depending on the parts you want to do, you may or may not need the following. hookupwire, soldering iron, wire cutters, etc.The leading outlets carry them but they can tend to be spendy, so maybe try or do a search for "16-key keypad" on google. Just for the record, the firmware was written for an ATmega328p, so it should run well on that class of AVR's and probably many others with little to no modification. Of course, your custom own ghetto setup will suffice too. Arduino, Bare Bones Kit, Freeduino, Boarduino, and all the other clones work just fine. You can buy everything online, although I've found if you check your local electronic warehouse/shop (if you have one) you will be able to pick up everything considerably cheaper, though. This device is simple enough that either changing the library or just writing the 10 lines of code yourself is not a problem, but just know about this "feature".This instructable doesn't have (m)any expensive components if you already have an AVR setup. ![]() I'm personally not a fan of this design choice as it can make for some difficult debug efforts for those who are new to writing firmware. The last "meh" bit is more of a warning to anyone reading this: The library will currently reset the I2C bus speed to 100kbit/sec for you. A sequential read to get all button presses would be nice too. Again, this eats time as you have to multiple sets of writes in order to read one button. As is, you have to write a 1 to register 0圆 before a read. It would also be nice to see the FIFO read simply be a read from a register. You can reprogram the chip to run at a faster rate to get 400kbit/sec, but programming an already-soldered ATtiny85 is a bit of a pain. While you wouldn't ever need to read button presses that fast, it would save a bit of processor time during the waits. It would be nice to see a slightly faster processor on here that can handle 400kbit/sec and 1Mbit/sec speeds that are selectable via solder jumpers. You can change the I2C bus speed on most controllers on the fly, so this isn't the end of the world, but it does eat a few extra clock cycles to switch back and forth. This keypad only works at an I2C speed of 100kbit/sec which makes it a bit of a pain to use alongside other I2C devices when high speed is required. Offloading constant keypad scans to a side board is fairly nice and pretty convenient. It does what it is supposed to do for a decent price. This reduces the amount of required PCB space, and polarized connections mean you can’t hook it up wrong. All Qwiic-enabled boards use a common 1mm pitch, 4-pin JST connector. ![]() The SparkFun Qwiic connect system is an ecosystem of I 2C sensors, actuators, shields and cables that make prototyping faster and less prone to error. If you need to use more than one Qwiic Keypad sensor consider using the Qwiic Mux Breakout. A multiplexer/Mux is required to communicate to multiple Qwiic Keypad sensors on a single bus. NOTE: The I 2C address of the Qwiic Keypad is 0x4B and is jumper selectable to 0x4A (software-configurable to any address). The SparkFun Qwiic Keypad even has a software configurable I 2C address so you can have multiple I 2C devices on the same bus. ![]() This information, then, is accessible through the Qwiic interface. The Qwiic Keypad reads and stores the last 15 button presses in a First-In, First-Out (FIFO) stack, so you don’t need to constantly poll the keypad from your microcontroller. However, we still have broken out 0.1"-spaced pins in case you prefer to use a breadboard.Įach of the keypad's 12 buttons has been labeled 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, *, and # and has been formatted to into the same layout as a telephone keypad with each keypress resistance ranging between 10 and 150 Ohms. No voltage translation or figuring out which I 2C pin is SDA or SCL, just plug and go! Utilizing our handy Qwiic system, no soldering is required to connect it to the rest of your system. Keypads are very handy input devices, but who wants to tie up seven GPIO pins, wire up a handful of pull-up resistors, and write firmware that wastes valuable processing time scanning the keys for inputs? The SparkFun Qwiic Keypad comes fully assembled and makes the development process for adding a 12 button keypad easy.
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