This app note describes the common IC interface protocols like I2C, SPI, and GPIO. Also some problems covered with these interfaces that turn happy faces to sad. [via]
How can an interface change a happy face to a sad face? Engineers have happy faces when an interface works properly. Sad faces indicate failure somewhere. Because interfaces between microprocessors and ICs are simple—even easy—they are often ignored until interface failure causes sad faces all around. In this article, we discuss a common SPI error that can be almost impossible to find in a large system. Links to interface tutorial information are provided for complete information. Noise as a system issue and ICs to minimize its effects are also described.
Common IC interface problems - [Link]
Here you can find links to technical articles written by TI engineering experts for engineering trade magazines. Topics include how to select or design with amplifiers, data converters, clocks, interface and power management. They also address applications, such as audio, industrial, medical, high reliability and many others. Several sorting options can help you with your search
TI Technical Articles - [Link]
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]
The keyboard is the most common way for humans to input information into a computer. It has been around since before computers were main-stream and everyone was still using typewriters. Because of this prevalence in society, it’s important that we understand how to interface to the basic PS/2 keyboard.
This article will describe and show you an example of how to create a system capable of interacting with a keyboard in order to understand what keys have been pressed. The example system will be built on a breadboard using a PIC microcontroller to communicate with the keyboard and display output.
PS/2 Keyboard Interface - [Link]
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]
This is a low-cost prototype electrooculography (EOG) system, based on the ATmega328P, that allows people with motor disabilities to write text on a screen using only eye movements. Luis explains: [via]
The human eye is polarized, with the front of the eye being positive and the back of the eye being negative. This is caused by a concentration of negatively charged nerves in the retina on the back of the eye. As the eye moves the negative pole moves relative to the face and this change in the dipole potential can be measured on the skin in micro volts. To translate this voltage into a position, two sets of electrodes are used to measure the differential voltage in the vertical and horizontal direction, on this project, however, just horizontal movements are recorded.
Honduran High Schooler’s Low-Cost Eye-Controlled Interface – [Link]
This is a USB interface board I’ve built around a PIC 18f4550 microcontroller from Microchip. As many of you probably know, I’ve used my computer’s parallel port to connect many things to my computer. However, most laptops don’t have parallel ports these days, so I needed a way to connect things without a parallel port. This board does exactly that (and actually much, much more). I found a really nice tutorial on building this board here – http://eegeek.net/content/view/13/32/
Homemade USB interface board using a PIC – [Link]
Here’s a MIDI keyboard interface project from SuLuLab. It uses an Arduino, MIDI Shield, addressable RGB LED strip based on chip HL1606, 5VDC 1.5A PSU for strip supply (USB port current is not enough), and the Arduino’s FastSPI_LED library. [via]
MIDI messages from the keyboard (real or simulated on PC) enter the MIDI Shield’s MIDI IN and are presented to the Arduino serial port. The Arduino firmware interprets the MIDI messages NoteOn NoteOff, associates each key on the five octaves (60 keys) keyboard to a strip LED and lights it with color associated with the note. In the firmware to control the strip we used the FastSPI_LED library that allows you to address every single LED and turn the desired color (R, G, B).
For more details and to download firmware see the SuLuLab website and scroll to bottom of page for English version.
Arduino MIDI RGB display interface – [Link]
USB has recently become one of the most popular types of communication for devices ranging from consumer products, to industrial robotics and test equipment. The protocol relies heavily on constant contact with devices for error checking which makes it a bit cumbersome, but the end result is stability and high through-put speeds that operating systems love. With such popularity, understanding how to communicate with a USB host (like on a laptop) becomes an essential piece of information for anyone wishing to build a USB enabled device.
Simple PIC USB Interface – [Link]