By Andrew Liszewski
The STM32, for a lack of a better description, is a small personal computer that has roughly the same processing power as a PDA or cellphone. Out of the box it can run a simple GUI OS and a handful of games, but it’s really designed to be customized for whatever pocketable computing needs you might have. Jingxizhang has posted a project and code on the STM32 Primer website which shows how they turned the device into a pocket sized ECG.
This project is for detecting human ECG (Electrocardiogram, or EKG). A tiny amplifier is embedded (<1mA). The on-chip Timer, ADC and DMA (double buffering) are used for getting ECG data. An IIR filter and hardware LCD scrolling are used for ECG rendering. User can simply touch the Primer by 2 hands, his/her ECG trace is scrolling alive on the LCD screen. The instant heart rate is displayed with beep sound and LED flashing. The device also delivers and displays the ECG on a PC through the USB cable.
Two copper foils were added to each side of the STM32 which act as the ECG electrodes. The user simply has to place both their thumbs on the foils to see a scrolling trace of their heartbeat on the LCD, and a beep sound that coincides with each pulse.