This is a final year project by the students of Cornell University and utilizes ultrasonic range finders and haptic feedback to facilitate indoor navigation for the visually impaired. It uses auditory cues, such as sounds from the natural environment or sounds created artificially, to determine an individual’s surrounding physical space for the purpose of navigation. The device is a head-mounted navigation system with a wearable tactile sensor connected via a long flexible wire and also instructs the user to turn either left or right depending upon the obstacles.
The microcontroller used for the ultrasonic wayfinder is the ATmega1284 which is mounted on a custom made PCB. Apart from it, there are vibrating-disc type motor which were used as a haptic feedback. The device detects objects quickly with 1 inch resolution between 0 inches to 254 inches. However the accuracy will mostly depend upon the ultrasonic sensor used. The project is entirely made for indoor use as it can’t detect obstacle placed at 5 meters. They also have a plan to put on an additional range finder mainly on the head to detect ramps and stairs.
This project is about a LED based asynchronous fireflies which were used as a Christmas project. The aim of the project was to make a low-power, low parts count module that can sense when it’s dark and then mimic the blinking patterns accordingly. For the project he’s using an Atiny85 along with an external clock which was programmed by setting external fuse-bits which is a conventional way to set clock source or frequency in almost all type of AVR’s
A good things about the project is, it’s completely hand-made and that include the making PCB’s at home. To etch the PCB cupric chloride was used which is one of the quickest process to etch PCB but the time might depends upon the temperature. Also, to transfer the PCB design, from the computer to PCB, tone transfer method was used which is very impressive. An impressive project overall, but the complexity can be reduced if one uses in internal clock.
This mouse is a kind of a special mouse developed by students of Cornell University. In simple words, it’s a wireless mouse unit that requires no flat surface by using ultrasonic positioning. They have used ultrasonic sensor to represent the mouse position in space. To simulate the mouse buttons, touch based input buttons were put into the picture. There are three ultrasonic receivers attached to three corners of a board simulating the computer screen. Therefore for a particular position, based on the delay time, the position of the object is calculated.
The design has been implemented using two MCU’s one to generate the data representing the mouse coordinates and clicks activities, the other to import the data to the PC. The two MCU communicate wirelessly using XBEE protocol. The mouse responds reasonably fast to user’s action in general. It has a noticeable delay of a few tenths of a second which is due to present of filters. The concept is really amazing, but the device might be not that accurate or fast.
You probably are familiar with SD card lock switch. It is supposed to write protect the contents of memory once switched to “Write Protect” position. But fact is that there are many SD readers and sockets that simply ignore this switch and no matter what position switch is on, you can write to this card. So this is not the best way to protect data. But there is a way out. SD card has an internal TMP_WRITE_PROTECT bit in CSD register. So if this bit is set, you cannot write to to card – just read.
There are other protection layers here like PERM_WRITE_PROTECT bit in same CSD register which can be set once and you get permanent read-only SD card. This one probably is less practical as you are left with fixed data on card. In some cases this is great. Also there is a password protection possibility. Which allows setting 16-bytes password to protect from reading or writing until correct password is sent from host. As SD cards can be interfaces via SPI, this is pretty easy to manipulate protection bits. Originally Karl Lunt has built an SD locker device based on Atmega328p microcontroller. His device Was placed in side Altoids can. Lock/unlock operation can be done with single push button. LED indicates weather card is locked or unlocked. Another more elegant version was built by Nephiel, who replaced Atmega328p with Attiny85 microcontroller which is smaller in size but still has enough power to do the job. So if you are storing valuable information and don’t want it to be corrupted in some way – SD card locker is right choice.