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22 Jun 2015


by Mircea Daneliuc:

An electronics enclosure with HMI ( I2C LCD and keypad) for projects with sensors and relays. Good for any MCU, Arduino, Beaglebone,AVR

I have searched the net high and low to find a professional looking enclosure with an HMI (Human Machine Interface) that I could use in my project involving sensors and relays, but I wasn’t able to find one. Not for a decent price, that is… Most of the Arduino cases or enclosures were nice little boxes with slots for USB and power adapter but with no real functionality, not enabling the microcontroller to relate to the outside world in any way.

Arduino, Beaglebone, MCU enclosure with HMI (LCD & keypad) – [Link]

26 Jan 2015


by paulbleisch.com:

My son got one of these Leap Frog toys a few years ago as a gift. He enjoys playing with it very much. I am not sure how much counting and learning he is doing but it makes funny noises and sings to him so its a lot of fun.

Recently the unthinkable happened. It died. Not the batteries but something else. I took the back off to look at what might be wrong (which was very easy for a toy). Unfortunately, other than the speaker, a switch, battery compartment, and a ribbon cable to the front, there wasn’t much to investigate. A couple of glop tops and nothing else. I fiddled a bit more with it but everything “external” seemed fine.

Make a Custom Membrane Keypad for Arduino – [Link]

4 Jun 2014


by praveen @ circuitstoday.com:

Digital code lock or digital combination lock are a type of digital locks where a combination of digits/characters or both are used for unlocking the lock. This article is about a simple digital code lock using arduino. Here the code consists of a combination of digits from 1 to 6. There are separate keys for locking and unlocking the system. The system can be unlocked by pressing the unlock button after entering the correct combination of digits. A hex key pad is used as the input device. Only the first two rows of key (1, 2, 3, A, 4, 5, 6, B) are used in this project. A is used for locking the system and B is used for unlocking the system. Read this article Interfacing hex keypad to arduino for knowing more about hex keypad and its interfacing to the arduino. The circuit diagram of the digital code lock using arduino is shown in the figure below.

Simple digital code lock using arduino – [Link]

27 May 2014


by Tony Keith:

You have a project that accepts commands using a 16 button keypad and want to perform validation on the commands as each character is typed. But how? Use state machine logic / programming to solve the problem. If you aren’t familiar with or haven’t used state machine logic in programming, it is the easiest way to to break complex problems into manageable states and state transitions especially for handling serial input. One of the easiest ways to implement a state machine is to use a switch statement. In my opinion it is the only way to implement serial input commands.

Keypad Input Validation using State Machine Programming – [Link]

18 May 2014

KeyPadEncoderTitleRaj @ embedded-lab.com build an encoded matric keypad. He writes:

Matrix keypads are an excellent way of providing user input data into microcontroller-based systems. Keypads find applications in remote controls, standalone data-loggers, security systems, door entry systems, calculators, microwave ovens, etc. They are usually implemented as pushbutton switches arranged in a row and column matrix format to reduce the number of I/O connections. For example, a 16-switch keypad is arranged in a 4 X 4 matrix format requiring 8 I/O connections. A pressed key is detected and identified by scanning the keypad to look for a short circuit condition between a row and a column wire. The keypad scanning can be done either by polling or by means of an interrupt routine. In the polling approach, the scanning process is repeated in a continuous loop, which results in waste of CPU time. The interrupt-approach is more efficient and it notifies the processor when there is a keystroke. Another approach of interfacing a keypad to the microcontroller is by using a dedicated keypad encoder IC, which further reduces the I/O connections and makes the interface much simpler. In this project, we are building a simplified 16-switch keypad using the MM74C922 encoder chip, which converts a key switch closure to a 4-bit nibble output.

MM74C922N-based encoded matrix keypad – [Link]

22 Apr 2014
Cross-section of piezo button assembly

Cross-section of piezo button assembly

by Francesc Casanellas:

This design was done to get a sealed keypad for very wet environments (in my particular case, showers for swimming pools). The keypad needed to be able to detect slight pressure on a stainless steel plate 0.4mm thick. Apart from water protection, the solution offers an esthetical finish, as the user side is absolutely flat, with nothing visible other than the silkscreened print. Another advantage of this type of keypad is that it is vandal-proof. The core of the sensor is a piezoelectric disc, the type normally used as a buzzer. I chose the Murata 7BB-35-3. With 35mm of external diameter, it allows a sensitive area of about 20mm diameter.

Water & vandal-proof keypad uses piezoelectric disc as sensor and buzzer – [Link]

2 Feb 2012

phirephly build a debounced breadboard keypad:

I’ve been getting tired of having to wire up buttons and paste in debounce code (or wire up debouncers for TTL projects) every time I want any kind of user input.

I was browsing around Maxim’s site, when I stumbled upon the MAX6816-6818 series of button debouncers. These are single, dual, and octal channel debouncers. Attached is the design files for a simple eight-button breakout board for the MAX6818 designed to be plugged into a breadboard. In addition to the eight active-low debounced outputs, the edge connector includes an active-low button-change interrupt, and an active low enable input, which can be optionally solder-jumpered on, if the button outputs don’t need to be tri-stated.

Debounced breadboard keypad – [Link]

5 Sep 2011

embedded-lab.com writes:

Matrix keypads are very common input devices in embedded systems. They have simple architecture and are easy to interface. One good thing about them is that they allow you to interface a large number of input keys to a microcontroller with minimum usage of I/O resources. This tutorial describes two different approaches of reading input data from a 4×4 (16 keys) matrix keypad interfaced to a PIC microcontroller. The pressed key information is displayed on a character LCD. The microcontroller used in this experiment is PIC16F1827.

Matrix keypad interfacing – [Link]

8 May 2011

bildr.org writes:

Keypads are everywhere; on your cellphone, on your TV remotes, on your stereo and now on your Arduino. Wait…. Why do you want a keypad on your Arduino? Well it’s a pretty useful device to input numbers and letters (example: telephones), it can also be used for security measures like a keypad door lock, and it’s prefect when you need a low-cost and accessible interface for your next idea. After all, It wouldn’t be practical to use a single button or a potentiometer to input your Pin on an ATM. So for this tutorial, we will be going over Sparkfun’s 12 buttons keypad (0-9, #, * ), and get you all set up with some code and schematic too.

Arduino Keypad – [Link]

13 Mar 2011

1324itouch writes:

Hello everybody!!!
I have been messing around with a few components and my arduino. I figured out this project last week and just had to share it with all of you. What it is, is a laser beam hitting a photo cell. The arduino reads the photo cell and when it detects the voltage level is below a certain amount, the beam must be broken while sounding an alarm. The alarm stays on until you punch in the code you have set up to the keypad in. Once the correct code is typed in, the arduino turns of the buzzer and gives you 15 seconds ( or what ever you set the delay time to) to reset the laser beam. You are able to change the code if you like. The steps are very easy to follow and i hope everyone makes one!!!

Arduino laser detector with keypad – [Link]





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