Diff: example-stddev.cpp

Revision:

0:1610faecade6

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/example-stddev.cpp	Tue Sep 22 20:17:13 2020 -0400
@@ -0,0 +1,100 @@
+#include "KX134.h"
+#include "math.h"
+#include "mbed.h"
+
+#include <inttypes.h>
+
+#define PIN_SPI_MOSI PB_5
+#define PIN_SPI_MISO PB_4
+#define PIN_SPI_CS PA_4
+#define PIN_SPI_SCK PB_3
+#define PIN_INT1 PA_0 // placeholder
+#define PIN_INT2 PA_0 // placeholder
+#define PIN_RST PA_0  // placeholder
+
+int main(void)
+{
+    KX134 kx134Obj(PIN_SPI_MOSI, PIN_SPI_MISO, PIN_SPI_SCK, PIN_SPI_CS,
+                   PIN_INT1, PIN_INT2, PIN_RST);
+
+    if(!kx134Obj.init())
+    {
+        printf("Failed to initialize KX134\r\n");
+        return 1;
+    }
+
+    printf("Successfully initialized KX134\r\n");
+
+    int hz = 6400;
+
+    // initialize asynch reading
+    kx134Obj.enableRegisterWriting();
+    kx134Obj.setOutputDataRateHz(hz);
+    kx134Obj.setAccelRange(KX134::Range::RANGE_64G);
+    kx134Obj.disableRegisterWriting();
+
+    size_t numTrials = 200;
+    float gravs[numTrials][3];
+
+    for(size_t trialIndex = 0; trialIndex < numTrials; ++trialIndex)
+    {
+        float time = 1.0 / (float)hz * 1000.0;
+        ThisThread::sleep_for(time);
+
+        int16_t output[3];
+        kx134Obj.getAccelerations(output);
+        float ax = kx134Obj.convertRawToGravs(output[0]);
+        float ay = kx134Obj.convertRawToGravs(output[1]);
+        float az = kx134Obj.convertRawToGravs(output[2]);
+
+        printf("KX134 Accel: X: %" PRIi16 " LSB, Y: %" PRIi16
+               " LSB, Z: %" PRIi16 " LSB \r\n",
+               output[0], output[1], output[2]);
+        printf("KX134 Accel in Gravs: X: %f g, Y: %f g, Z: %f g \r\n", ax, ay,
+               az);
+
+        gravs[trialIndex][0] = ax;
+        gravs[trialIndex][1] = ay;
+        gravs[trialIndex][2] = az;
+    }
+
+    float average[3] = {0};
+    float maxGravs[3] = {0};
+    float minGravs[3] = {std::numeric_limits<float>::max()};
+
+    for(size_t trialIndex = 0; trialIndex < numTrials; ++trialIndex)
+    {
+        for(int i = 0; i < 3; ++i)
+        {
+            average[i] += gravs[trialIndex][i];
+            maxGravs[i] = std::max(gravs[trialIndex][i], maxGravs[i]);
+            minGravs[i] = std::min(gravs[trialIndex][i], minGravs[i]);
+        }
+    }
+
+    for(int i = 0; i < 3; ++i)
+    {
+        average[i] /= numTrials;
+    }
+
+    float variance[3] = {0};
+    for(size_t trialIndex = 0; trialIndex < numTrials; ++trialIndex)
+    {
+        for(int i = 0; i < 3; ++i)
+        {
+            variance[i] += pow(gravs[trialIndex][i] - average[i], 2);
+        }
+    }
+
+    float stdDeviation[3];
+    for(int i = 0; i < 3; ++i)
+    {
+        variance[i] /= numTrials - 1;
+        stdDeviation[i] = sqrt(variance[i]);
+    }
+
+    printf("Average Gravs at %d Hz: %f x, %f y, %f z\n", hz, average[0],
+           average[1], average[2]);
+    printf("Standard Deviation at %d Hz: %f x, %f y, %f z\n", hz,
+           stdDeviation[0], stdDeviation[1], stdDeviation[2]);
+}