Embedded projects from around the web

Portable digital stethoscope with record and playback

admin — Wed, 16 May 2012 11:23:46 +0000

Stethoscopes are intensively used by physicians. Some of them are modern other are old fashioned. But in many cases technology may help to see what human may skip/not notice. This is why computer aided diagnosis (CAD) is important. Having this in mind Cornel ECE4760 students Michael Wu and Garen Der-Khachadourian constructed a digital stethoscope with many useful features that may be helpful when analyzing cardiac signals.

Digital stethoscope is based on AVR Atmega644 microcontroller which captures sound signal using sensor and digitizes at 8kHz. All captured signals are passed to audio output using PWM for real time auscultation. Additionally signal waveform is recorded in to 1MB external flash memory chip so later waveform could be played back. User interactions are seen in 4×20 LCD and controlled with 16 button keypad. Besides that digital stethoscope sends real time (or recorded) waveform data via USART where Matlab program analyzes it and calculates other derivative information like average hear-beat rate. Having visual information such system may help to detect cardiac murmur that can be unnoticed during standard checkups.

AVR Interprets Morse code

admin — Tue, 15 May 2012 12:06:23 +0000

Morse code is basically dashes and dots. Each character is encoded using a mix of them. Human can learn Morse code during some practice. If you don’t want to learn it but still need to decode some messages you can build a simple Morse code interpreter which listens to beep signals and translates messages in to readable text.

WPvideo 1.10

This system is based on Atmega8 microcontroller which reads sound signals using microphone and operational amplifier. Then microcontroller reads sound signals using ADC and determines weather particular signal were dash or dot. It can translate 32 characters including aA- zZ and 0-9. Messages are displayed on standard 2×16 LCD.

OK-Wake device tells kid when to get up

admin — Mon, 14 May 2012 12:53:32 +0000

We all know how sweet sleep can be in the morning. Every last minute counts… If there are kids around then things get different. Simply speaking – they dictate when to wake up and get up. Most frequently this is because kids don’t have a sense of time. So Mike decided to add a little control to kids wake process.

He built an attiny25 based clock called OK Wake. It has a NXP PCF8523 RTC running on it. As kids cant tell time there is no a display just dual color LED. Device simply indicates three parts of day – night, twilight and dawn. Each of them is set to particular time for instance if wake time is 6am, then twilight starts at 5:30am with slow red blink. When time reaches wake time LED turns green wit h”breathing” blink. Kids are great at lights – so when LED turns green its OK to start buzzing arround the house

Arduino based alarm system that sends SMS

admin — Sun, 13 May 2012 12:08:31 +0000

Alarm systems tend to be more reliable when you can get status messages anywhere you are. Usually such systems uses a GSM modules that are quite expensive. If your protected object isn’t very critical you can try simple version like following which is based on Arduino. It is equipped with motion sensor and is connected to PC.

Arduino communicates with python server using serial port. The rest job is done by python which connects wot TelAPI account and triggers SMS message. All you have to do is to register and get your account SID. Using such simple system you can get same as you would do with GMS module. Currently system is set up to send SMS every 30 minutes while motion is detected. Parameters can be easily configured in sketch.

Driving Seven segment LED display using serial interface

admin — Sat, 12 May 2012 13:55:57 +0000

Seven segment LED displays a great way to indicate basic numeric and text information. They are visible in a dark an from larger distances comparing to LCD. Driving one seven segment display is a piece of cake using any MCU. But when it comes to larger number of indicators you may start scratching head looking for best way to drive them.

Embedded-lab have constructed a great kit which includes a nice PCB that houses a four seven segment LED indicators. They are driven using MAX7219 which is special chip to drive up to 8 indicators. It accepts data via SPI interface, so it is no problem to get it working with any MCU. You will find couple examples including simple PIC12F683 up counter and Arduino demo.