這個小東西簡單而好玩，心代碼可以做為單片機入門的率測量儀一個課業(yè)設(shè)計。
將你的品賞食指輕輕地放在傳感器上，就能看到LED指示燈隨著你的析附心跳而閃動，15秒鐘以后，簡單還能在數(shù)碼管上顯示你當(dāng)前的好玩心率。
核心部分在傳感器上，心代碼這里用的率測量儀是一套紅外對管。
人體指尖的品賞動脈比較發(fā)達，當(dāng)動脈血管隨心臟周期性收縮與舒張時，析附血管中的簡單血液容積也會發(fā)生變化。
這時紅外接收探頭便能采集到的好玩相應(yīng)的光脈沖信號，經(jīng)過去噪和放大后送到單片機，心代碼進行運算處理，便得到了心率數(shù)據(jù)。
采集部分的原理圖
運算與顯示部分的原理圖
單片機代碼
/*
Project: Measuring heart rate through fingertip
Copyright @ Rajendra Bhatt
January 18, 2011
PIC16F628A at 4.0 MHz external clock, MCLR enabled
*/sbit IR_Tx at RA3_bit;
sbit DD0_Set at RA2_bit;
sbit DD1_Set at RA1_bit;
sbit DD2_Set at RA0_bit;
sbit start at RB7_bit;
unsigned short j, DD0, DD1, DD2, DD3;
unsigned short pulserate, pulsecount;
unsigned int i;
//-------------- Function to Return mask for common anode 7-seg. display
unsigned short mask(unsigned short num) {
switch (num) {
case 0 : return 0xC0;
case 1 : return 0xF9;
case 2 : return 0xA4;
case 3 : return 0xB0;
case 4 : return 0x99;
case 5 : return 0x92;
case 6 : return 0x82;
case 7 : return 0xF8;
case 8 : return 0x80;
case 9 : return 0x90;
} //case end
}void delay_debounce(){
Delay_ms(300);
}void delay_refresh(){
Delay_ms(5);
}void countpulse(){
IR_Tx = 1;
delay_debounce();
delay_debounce();
TMR0=0;
Delay_ms(15000); // Delay 1 Sec
IR_Tx = 0;
pulsecount = TMR0;
pulserate = pulsecount*4;
}void display(){
DD0 = pulserate%10;
DD0 = mask(DD0);
DD1 = (pulserate/10)%10;
DD1 = mask(DD1);
DD2 = pulserate/100;
DD2 = mask(DD2);
for (i = 0; i<=180*j; i++) {
DD0_Set = 0;
DD1_Set = 1;
DD2_Set = 1;
PORTB = DD0;
delay_refresh();
DD0_Set = 1;
DD1_Set = 0;
DD2_Set = 1;
PORTB = DD1;
delay_refresh();
DD0_Set = 1;
DD1_Set = 1;
DD2_Set = 0;
PORTB = DD2;
delay_refresh();
}
DD2_Set = 1;
}void main() {
CMCON = 0x07; // Disable Comparators
TRISA = 0b00110000; // RA4/T0CKI input, RA5 is I/P only
TRISB = 0b10000000; // RB7 input, rest output
OPTION_REG = 0b00101000; // Prescaler (1:1), TOCS =1 for counter mode
pulserate = 0;
j = 1;
display();
do {
if(!start){
delay_debounce();
countpulse();
j= 3;
display();
}
} while(1); // Infinite loop
}
HEX代碼
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來源：著名的PCB哥
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