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pulse/pulse.c

+#include <stdio.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <wiringPi.h>
+#include <wiringPiSPI.h>
+
+#define RATE_SIZE 10
+
+typedef struct
+{
+    int channel;
+    int BPM;
+    int bus;
+    int device;
+    int max_speed_hz;
+} Pulsesensor;
+
+typedef struct
+{
+    int bus;
+    int device;
+} MCP3008;
+
+void MCP3008_open(MCP3008 *adc)
+{
+    wiringPiSPISetup(adc->bus, adc->max_speed_hz);
+}
+
+int MCP3008_read(MCP3008 *adc, int channel)
+{
+    int cmd1 = 4 | 2 | ((channel & 4) >> 2);
+    int cmd2 = (channel & 3) << 6;
+
+    unsigned char data[3];
+    data[0] = cmd1;
+    data[1] = cmd2;
+    data[2] = 0;
+
+    wiringPiSPIDataRW(adc->bus, data, 3);
+
+    int result = ((data[1] & 15) << 8) + data[2];
+    return result;
+}
+
+void MCP3008_close(MCP3008 *adc)
+{
+    wiringPiSPIClose(adc->bus);
+}
+
+void getBPMLoop(Pulsesensor *sensor, MCP3008 *adc)
+{
+    int rate[RATE_SIZE] = {0};
+    int sampleCounter = 0;
+    int lastBeatTime = 0;
+    int P = 512;
+    int T = 512;
+    int thresh = 525;
+    int amp = 100;
+    int firstBeat = 1;
+    int secondBeat = 0;
+    int IBI = 600;
+    int Pulse = 0;
+    int lastTime = (int)time(NULL) * 1000;
+
+    while (1)
+    {
+        // MCP3008을 통해 센서 값을 읽어옴
+
+        int Signal = MCP3008_read(adc, sensor->channel);
+        int currentTime = (int)time(NULL) * 1000;
+
+        // 시간 간격을 측정하여 심장 박동의 타이밍 추적
+        // 마지막 측정으로부터 현재까지 경과된 시간, 측정 시간을 계속 누적
+        sampleCounter += currentTime - lastTime;
+        // lastTiem 업데이트
+        lastTime = currentTime;
+        int N = sampleCounter - lastBeatTime;
+
+        if (Signal < thresh && N > (IBI / 5.0) * 3)
+        {
+            if (Signal < T)
+            {
+                T = Signal;
+            }
+        }
+
+        if (Signal > thresh && Signal > P)
+        {
+            P = Signal;
+        }
+
+        if (N > 250)
+        {
+            if (Signal > thresh && Pulse == 0 && N > (IBI / 5.0) * 3)
+            {
+                Pulse = 1;
+                IBI = sampleCounter - lastBeatTime;
+                lastBeatTime = sampleCounter;
+
+                if (secondBeat)
+                {
+                    secondBeat = 0;
+                    for (int i = 0; i < RATE_SIZE; i++)
+                    {
+                        rate[i] = IBI;
+                    }
+                }
+
+                if (firstBeat)
+                {
+                    firstBeat = 0;
+                    secondBeat = 1;
+                    continue;
+                }
+
+                for (int i = 0; i < RATE_SIZE - 1; i++)
+                {
+                    rate[i] = rate[i + 1];
+                }
+                rate[RATE_SIZE - 1] = IBI;
+                int runningTotal = 0;
+                for (int i = 0; i < RATE_SIZE; i++)
+                {
+                    runningTotal += rate[i];
+                }
+                int averageIBI = runningTotal / RATE_SIZE;
+                sensor->BPM = 60000 / averageIBI;
+            }
+        }
+
+        if (Signal < thresh && Pulse == 1)
+        {
+            Pulse = 0;
+            amp = P - T;
+            thresh = amp / 2 + T;
+            P = thresh;
+            T = thresh;
+        }
+
+        if (N > 2500)
+        {
+            thresh = 512;
+            P = 512;
+            T = 512;
+            lastBeatTime = sampleCounter;
+            firstBeat = 1;
+            secondBeat = 0;
+            sensor->BPM = 0;
+        }
+
+        usleep(5000);
+    }
+}
+
+void startAsyncBPM(Pulsesensor *sensor, MCP3008 *adc)
+{
+    // 스레드를 시작하여 getBPMLoop 함수를 실행
+    pthread_t tid;
+    pthread_create(&tid, NULL, (void *)&getBPMLoop, sensor, adc);
+}
+
+void stopAsyncBPM(Pulsesensor *sensor)
+{
+    // 스레드를 중지하고 BPM을 초기화
+    sensor->BPM = 0;
+}
+
+int main()
+{
+    Pulsesensor sensor;
+    sensor.channel = 0;
+    sensor.BPM = 0;
+
+    MCP3008 adc;
+    adc.bus = 0;
+    adc.device = 0;
+    adc.max_speed_hz = 1000000;
+
+    MCP3008_open(&adc);
+    startAsyncBPM(&sensor, &adc);
+
+    while (1)
+    {
+        int bpm = sensor.BPM;
+        if (bpm - 155 > 0)
+        {
+            printf("BPM: %d\n", bpm - 155);
+        }
+        else
+        {
+            printf("No Heartbeat found\n");
+        }
+        usleep(1500000); // 1.5초 대기
+    }
+
+    stopAsyncBPM(&sensor);
+    MCP3008_close(&adc);
+
+    return 0;
+}