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原理图
LED指示灯闪烁至心脏跳动，并通过发光LED的数量和颜色显示当前的BPM。
硬件组件：
uECG设备× 1
Arduino Nano R3× 1
Adafruit NeoPixel Ring：WS2812 5050 RGB LED× 1
锂离子电池1000mAh× 1
手动工具和制造机器：
烙铁（通用）
实际上所有繁重的工作都是由uECG 完成的- 一种小型可穿戴心电图设备，它是开源的，具有Arduino友好的输出引脚（该引脚在每次心跳时变高/变低）。处理这些引脚状态比处理ECG信号更容易，我试图从中获得最大的收益。
Arduino源程序如下:
- #include <Adafruit_NeoPixel.h>
- #ifdef __AVR__
- #include <avr/power.h>
- #endif
- // DI pin of LED ring
- #define PIN 11
- // number of pixels in the ring
- #define NUMPIXELS 16
- // input pin for connecting uECG
- int in_pin = 3;
- Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);
- void setup() {
- pixels.begin(); // This initializes the NeoPixel library.
- pinMode(in_pin, INPUT); //set pin to input mode
- digitalWrite(in_pin, 1); //enable PULLUP: this is critical, uECG doesn't have internal pull-up
- }
- //we store last 20 heartbeats to averge BPM over them
- //with higher value, it will become more reliable,
- //but it will take more time to see output change when BPM changes
- #define BEAT_HIST 20
- long beats[BEAT_HIST];
- void push_beat(long ms) //shift all beats in array and insert current one
- {
- for(int x = 0; x < BEAT_HIST-1; x++)
- {
- beats[x] = beats[x+1];
- }
- beats[BEAT_HIST-1] = ms;
- }
- int get_bpm() //using time difference between first and last beats
- {
- long dt = beats[BEAT_HIST-1] - beats[0];
- long bpm = BEAT_HIST * 60000 / dt;
- return bpm;
- }
- long last_pix_upd = 0; //to keep track of when we updated pixels previous time
- int prev_in_state = 0; //previous state of input pin: we want to process only changes of state
- void loop()
- {
- long ms = millis();
- int in_state = digitalRead(in_pin); //1 when no beat detected, 0 in beat
- if(in_state == 1 && prev_in_state == 0) //react only to change
- {
- push_beat(ms);
- }
- prev_in_state = in_state;
- if(ms - last_pix_upd > 10) //don't update pixels too often
- {
- int r, g, b;
- last_pix_upd = ms;
- int bpm = get_bpm();
- int max_bright = 120; //value of maximum brightness, max 255. But you don't always want it at max :)
- float dd = 20; //change in BPM between color tones (blue->green->yellow->pink->red)
- float t1 = 90, t2, t3, t4; //t1 - "base" BPM, lower than t1 would be blue
- t2 = t1 + dd;
- t3 = t2 + dd;
- t4 = t3 + dd;
- //code for changing color depending in which t1...t4 range we are now
- if(bpm < t1){ r = 0; g = 0; b = max_bright; }
- else if(bpm < t2) { r = 0; g = max_bright * (bpm-t1)/dd; b = max_bright - g; }
- else if(bpm < t3) { r = max_bright * (bpm-t2)/dd; g = max_bright - r; b = r/4; }
- else if(bpm < t4) { r = max_bright; g = 0; b = max_bright/2 - max_bright * (bpm-t3)/(2*dd); }
- else {r = max_bright; g = 0; b = 0; }
- if(in_state) //when not in beat, 1/4 intensity, so only beats are highlighted
- {
- r *= 0.25;
- g *= 0.25;
- b *= 0.25;
- }
- int on_pixels = (bpm+5)/10; //number of used LEDs: for 60 BPM, 6 LEDs will be on, for 120 - 12 etc
- for(int i=0;i<NUMPIXELS;i++)
- {
- if(i < on_pixels) pixels.setPixelColor(i, pixels.Color(r,g,b));
- else pixels.setPixelColor(i, pixels.Color(0,0,0)); //turn off all other LEDs
- }
- pixels.show();
- }
- }
所有资料51hei提供下载:
使用ECG的心跳指示器.zip
(989.79 KB, 下载次数: 6)
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