kx126-pedometer (1).txt

#include <Wire.h>

// KX126-1063 I2C address
#define KX126_ADDR 0x1F

// Register addresses
#define KX126_WHO_AM_I          0x00
#define KX126_CNTL1            0x18
#define KX126_ODCNTL           0x1B
#define KX126_INC1             0x1C
#define KX126_INC2             0x1D
#define KX126_INC3             0x1E
#define KX126_WUFC             0x23  // Wake-Up Function Counter
#define KX126_PED_CNTL1        0x56
#define KX126_PED_CNTL2        0x57
#define KX126_PED_CNTL3        0x58
#define KX126_PED_CNTL4        0x59
#define KX126_PED_CNTL5        0x5A
#define KX126_PED_DATA         0x5B  // Step counter output

// Output pin for step threshold signal
const int SIGNAL_PIN = 13;  // Using onboard LED
const int STEP_THRESHOLD = 250;

// Variables for step counting
uint16_t stepCount = 0;
bool thresholdReached = false;

void setup() {
  Wire.begin();
  Serial.begin(9600);
  
  // Initialize output pin
  pinMode(SIGNAL_PIN, OUTPUT);
  digitalWrite(SIGNAL_PIN, LOW);
  
  // Check if sensor is responding
  byte whoAmI = readRegister(KX126_WHO_AM_I);
  if (whoAmI != 0x38) {  // 0x38 is the expected WHO_AM_I value for KX126
    Serial.println("Error: KX126 sensor not found!");
    while(1);  // Halt if sensor not found
  }
  
  // Initialize sensor for pedometer function
  initializePedometer();
  
  Serial.println("KX126 Pedometer initialized!");
}

void loop() {
  // Read step count from sensor
  uint16_t steps = readStepCount();
  
  if (steps != stepCount) {
    stepCount = steps;
    Serial.print("Steps: ");
    Serial.println(stepCount);
    
    // Check if threshold reached
    if (stepCount >= STEP_THRESHOLD && !thresholdReached) {
      digitalWrite(SIGNAL_PIN, HIGH);
      thresholdReached = true;
      Serial.println("Step threshold reached!");
    }
  }
  
  delay(100);  // Short delay between readings
}

void initializePedometer() {
  // Put sensor in standby mode to configure
  writeRegister(KX126_CNTL1, 0x00);
  delay(50);
  
  // Configure Output Data Rate (ODR) for pedometer - 50Hz
  writeRegister(KX126_ODCNTL, 0x02);
  
  // Configure pedometer settings
  // PED_CNTL1: Step counter ODR = 50Hz, count delay time = 96ms
  writeRegister(KX126_PED_CNTL1, 0x04);
  
  // PED_CNTL2: Peak threshold = 2.5g, Jerk threshold = 2.5g
  writeRegister(KX126_PED_CNTL2, 0x44);
  
  // PED_CNTL3: Timer = 150ms, Step time window min = 150ms
  writeRegister(KX126_PED_CNTL3, 0x44);
  
  // PED_CNTL4: Step time window max = 400ms
  writeRegister(KX126_PED_CNTL4, 0x44);
  
  // PED_CNTL5: Step counter watermark = 1 step
  writeRegister(KX126_PED_CNTL5, 0x01);
  
  // Enable pedometer function and put sensor in operating mode
  // CNTL1: Enable pedometer, set resolution to 16-bit, enable acceleration output
  writeRegister(KX126_CNTL1, 0xB2);
  
  delay(50);  // Wait for sensor to enter operating mode
}

uint16_t readStepCount() {
  // Read step counter value (2 bytes)
  Wire.beginTransmission(KX126_ADDR);
  Wire.write(KX126_PED_DATA);
  Wire.endTransmission(false);
  
  Wire.requestFrom(KX126_ADDR, 2);
  uint16_t steps = 0;
  if (Wire.available() >= 2) {
    steps = Wire.read();        // Low byte
    steps |= Wire.read() << 8;  // High byte
  }
  
  return steps;
}

void writeRegister(byte reg, byte value) {
  Wire.beginTransmission(KX126_ADDR);
  Wire.write(reg);
  Wire.write(value);
  Wire.endTransmission();
}

byte readRegister(byte reg) {
  Wire.beginTransmission(KX126_ADDR);
  Wire.write(reg);
  Wire.endTransmission(false);
  
  Wire.requestFrom(KX126_ADDR, 1);
  return Wire.read();
}

void resetStepCounter() {
  // Put sensor in standby
  writeRegister(KX126_CNTL1, 0x00);
  delay(50);
  
  // Clear step counter by toggling pedometer bit
  writeRegister(KX126_CNTL1, 0xB2);
  
  // Reset variables
  stepCount = 0;
  thresholdReached = false;
  digitalWrite(SIGNAL_PIN, LOW);
  
  Serial.println("Step counter reset");
}