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]
Matt writes in about RTS/CTS handshaking and waveforms…
I recently had the need to add RTS/CTS handshaking to the serial connection between my PC and my ATMega. I struggled with it for a time due to some misunderstandings on my part, and because I couldn’t find a writeup which described how the handshaking is supposed to work, and (more importantly for me) how it’s supposed to look. I eventually got it to work, and wrote it up in a way that would’ve been useful for me when I was trying to figure out how to make it work.
RTS/CTS handshaking and waveforms – [Link]
This hack is accomplished using the Universal Breakout Board (UBB) which slides into the SD slot providing access to these signals. The UBB interfaces with the VGA connector via a handful of resistors. The schematic and code for the Ben are posted on the project’s site.
Bitbang VGA from an SD card slot – [Link]
McZ found a sim card power supply with level translator:
The TXS4555 is a complete Smart Identity Module (SIM) card solution for interfacing wireless baseband processors with a SIM card to store I/O for mobile handset applications. The device complies with ISO/IEC Smart-Card Interface requirements as well as GSM and 3G mobile standards. It includes a high-speed level translator capable of supporting Class-B (2.95 V) and Class-C (1.8 V) interfaces, a low-dropout (LDO) voltage regulator that has output voltages that are selectable between 2.95-V Class-B and 1.8-V Class-C interfaces.
1.8V/3V sim card power supply with level translator – [Link]
Many different types of communication protocols exist and the PIC is able to use quite a few of them. USB, RS232 and Parallel are all common forms of digital communication that use a unique method for transferring data. Today we will focus on a protocol called I²C (pronounced I-squared-C).
PIC I2C Interface Tutorial – [Link]
This is a PS/2 to USB keyboard converter with some nice features.
PS/2 to USB keyboard converter – [Link]
A. J. Huitsing writes:
This page documents my hobby project of building a home-brew IR receiver/transmitter based on the FTDI chipset. During the past couple of years I’ve been using several IR receivers and transmitters that where based on RS232 connections. Unfortunately my newest boxes don’t have any legacy RS232 connections anymore. Googling around for a cheap USB based solution didn’t give me the results I hoped for.
Creating a home-brew IR receiver / transmitter with an FTDI chip – [Link]
Newer protocols are always fun to explore, such as the automotive CAN bus. Here’s a project by wire2wire which sniffs the CAN signals from steering wheel controls and converts them to a serial output. The main components are a PIC16F876, MCP2515 and MCP2551. [via]
CAN sniffing for steering wheel button presses – [Link]