ECG simulator width ATTINY45

motivation

For the examination of ecg systems, ecg monitors and ecg long-term recoders one needs a simulator of the heart activities. The devices commercially the available are very expensive and also not straight small. A goal should be a small portable ecg simulator, perhaps later also in the size of a key fob.

implementation

A ATTINY45 is the heart of the system. The ecg is put down digitized in an array and the controller read everything approx. 1,3msec this array. The ecg curve is produced by means of PWM and smoothed width a two-way low-pass filter. The further voltage dividers serve for to the allocation and different priority of the exits. Thus the ecg signal is available as R, L, F and N at the exits. The inserted LED flashes in the clock of the simulated heart frequency, which amounts to 90 pulses per minute. The current supply takes over a 9Volt battery with a 78L05. The actual working time amounts to purely computationally approx. 24h.

schematic:

Schaltplan

mechanical structure

The PCB is built into a plastic housing from Conrad. The item number is 522706. The srcew holes into the pcb are suitable to the attachments on the housing. In the housing is also place for the battery. Into the front plate the slide switch for ON/OFF is inserted and the LED. Contacting to the electrocardiogram electrodes is made by self made contact pins. After the flashing the firmware into the microcontroller is the simulator ready to use. The fusebits from the ATTINY45 are all Factory settings, the systemclock is running width 1MHz.

virtual PCB (created width Eagle3D from Matthias Weißer:

virtual PCB

finished simulator:

 finished simulator

download

AVR firmware written in C width WINAVR:

software.zip

PCB following soon

future prospects

The further development goes toward miniaturization up to size of a key fob and change-over between 2 pulse frequencies by means of push button. This is to then serve also for switching on and off.

Author: — Ronny Schmiedel 2009/10/10 23:49

 
en/projekte/ekg_simulator.txt · Zuletzt geändert: 2017/04/15 22:59 (Externe Bearbeitung)
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