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Toumas decided to code his own capacitive touch sensors based on a closed source Atmel example where a single ADC pin is used for capacitive sensing. He reverse engineered it, and documented his results: [via]
I’ve been thinking of a project that needs a little bit more elegant user interface than your usual push buttons. Partly inspired by a video blog on Dave Jones’ EEVblog, I decided to look into capacitive touch buttons. The big issue unfortunately for me was that you usually need a separate chip for capacitive touch sensing. With some tricks, you can however use a normal microcontroller to do the job. Even using only a single pin and resistor.
Capacitive touch sensing with a single ADC pin - [Link]
Two independent touch switches housed in a single 8 pin chip. Power supply between 2V and 5V. New version 2.0 has Individually configurable momentary or latching operation.
Have you have ever wanted to add a simple touch switch to your project? Well now you can with our touch switch IC you can now add momentary or locking touch switch functionality.
Outputs can be momentary or latching
- For momentary operation connect the CFG1 / CFG2 pin to Ground.
- For latching operation, connect the CFG1 / CFG2 pin to +VDD.
Touch Switch IC - [Link]
Giorgos Lazaridis writes:
An AC Hum touch sensor is a very special technique, rarely used for switching applications, because it has a great disadvantage. In order to operate normally, an active AC power line has to be near by. More info about this type of touch sensor, along with other types (including the capacitance method), can be found in the corresponding theory page, how the touch buttons work..
DIY AC Hum Touch Button - [Link]
pyroelectro.com writes:
Touch screen or touch activated technology has been around for a few decades now, but only recently have prices dropped and the technology been (somewhat) perfected. As an input device touch screens offer a more natural interaction that humans are used to, which offers a great advantage for businesses selling to the general public over traditional keyboards and mouses.
This article will look at how to interface to a 4-wire resistive touch screen and find out the X and Y coordinates of the current point being touched. A minimal number of parts will be used to simplify the system hardware, and to focus more on the theory of how it works.
Simple Touch Screen Interface - [Link]
Tic Tac Touch @ The Custom Geek… [via]
OK, so I haven’t posted in a while because I have been working on some bigger projects, but yesterday, I took a two hour break and made a 2 player tic tac toe game. I did this with an Arduino and a 2.8″ touchshield from Adafruit.com. It’s pretty basic tic tac toe, and has score tracking, game logic (you can’t go twice in a row, and telling you if you win), and the ability to consume a chunk of time playing tic tac toe with my son. Below is the code, feel free to hack modify etc. If you play against a smart person (or yourself), you will have lots of Mosfet eye games!
Tic Tac Touch - [Link]
pcbheaven.com writes:
I believe that kids (and not only kids) that have their hands on electronics, wanted at least once in their lives to make an electronic keylock system for their house or room. When i was a kid, i had bought a Smart Kit Keycode lock system, and i had adapted it on the external door of my house. But this door had already the automatic-release mechanism. I only had to find which wires actuate this mechanism and hook the relay of the kit in parallel to this.
Then, i discovered that making a key-code circuit, is simple, very simple. As a matter of fact, so simple, that i designed this very simple key-code circuit, similar to the one from smart-kit but much better (mine had automatic reset operation when wrong code was entered), which took me only a few hours to design. Not to mention the microcontrollers… But why don’t i have a keycode-lock for my apartment’s door? Simple because it is expensive and needs a great mod on the door or frame.
Servo-Actuated Door Keylock Hack with capacitance touch-pad – [Link]
civicbynature writes -
Thanks to jersagfast @ TheCustomGeek. He wrote an awesome menu program for adafruits 2.8tft breakout board. It has 5 different menu areas as well as a settings area for backlight brightness and sleep timers which saves the settings to EEPROM so the settings are saved even when there’s no power. Plus many more features. I have added many updates. It is now both UNO and Mega 1280/2560. compatible.
I have also added the ability to read actual Vcc voltages at the core using the Bandgap method For accurate voltage readings and sensor readings. And more. If you’d like to check out the latest code it’s available Here on my site.
Cool 2.8″ TFT Touch project… - [Link]
adafruit.com writes:
2.8 TFT Touch Shield for Arduino. Spice up your Arduino project with a beautiful large touchscreen display shield with built in microSD card connection. This TFT display is big (2.8″ diagonal) bright (4 white-LED backlight) and colorful (18-bit 262,000 different shades)! 240×320 pixels with individual pixel control. It has way more resolution than a black and white 128×64 display. As a bonus, this display has a resistive touchscreen attached to it already, so you can detect finger presses anywhere on the screen.
2.8 TFT Touch Shield for Arduino - [Link]
ghmicro.com writes:
I designed a keypad board for the Freescale MPR121 Capacitive Touch Sensor Controller chip and received it in my latest batch of boards from dorkbotpdx.org. I’m really happy with this one. The MPR121 is really easy to use and, though it has tons of internal adjustments and controls to suit almost any sensing job, works perfectly with all default settings for my little board.
MPR121 Touch Sensor Controller – [Link]
This project is a resistance touch button based on simple components.
R1 is a simple protective resistor. On pins E1 and E2, the two electrodes are connected to perform the touch plates. T1 is a transistor amplifier. I choose to use a darlington pair transistor, because i want to have enough current amplification to drive loads such as a relay, even if your skin is completely dry. You could use a simple transistor as well if you plan to drive simple LEDs or other low current loads. The next transistor is a power switching transistor, able to deliver enough current for the relay. A capacitor is connected to its base, to eliminate bounces or other parasitic noise. It causes a slight ON-OFF delay, but it is extremely fast to notice.
Resistance Touch Button – [Link]
