feat: implement handler for distance and led

distance.py

@@ -0,0 +1,84 @@
+import machine
+import time
+from i2c_handler import I2CSlaveHandler, Packet
+
+class DistanceHandler(I2CSlaveHandler):
+    """
+    I2C handler that responds to master requests by sending distance values
+    from an HC-SR04 ultrasonic sensor.
+    """
+
+    def __init__(self, i2c_id, sda, scl, slave_addr, trig_pin, echo_pin):
+        super().__init__(i2c_id, sda, scl, slave_addr)
+        self.trig = machine.Pin(trig_pin, machine.Pin.OUT)
+        self.echo = machine.Pin(echo_pin, machine.Pin.IN)
+
+    def read_distance_mm(self):
+        """
+        Measure distance using the HC-SR04 sensor.
+        Returns distance in millimeters as an integer.
+        """
+        # Send a 10us pulse to trigger
+        self.trig.low()
+        time.sleep_us(2)
+        self.trig.high()
+        time.sleep_us(10)
+        self.trig.low()
+
+        # Wait for echo high (timeout after 25ms)
+        timeout = 25000
+        start = time.ticks_us()
+        while not self.echo.value():
+            if time.ticks_diff(time.ticks_us(), start) > timeout:
+                return 0  # sensor error
+        t1 = time.ticks_us()
+        while self.echo.value():
+            if time.ticks_diff(time.ticks_us(), t1) > timeout:
+                return 0  # sensor error
+        t2 = time.ticks_us()
+
+        # Calculate duration and distance
+        duration = time.ticks_diff(t2, t1)
+        distance_mm = (duration * 100) // 582
+        # HC-SR04: distance (mm) = duration (us) / 5.82
+
+        # Clamp to 0..65535
+        return max(0, min(distance_mm, 65535))
+
+    def process_request(self):
+        """
+        Called when master requests data. Responds with a packet containing distance.
+        Packet format:
+        Byte 0: 0x01 (distance command)
+        Byte 1: reserved
+        Byte 2-3: distance (uint16, mm, little-endian)
+        Byte 4-6: reserved
+        Byte 7: checksum (xor of bytes 0-6)
+        """
+        #dist = self.read_distance_mm()
+        dist = 155
+        data = [0] * Packet.LENGTH
+        data[0] = 0x01  # Command: distance
+        data[2] = dist & 0xFF  # Low byte
+        data[3] = (dist >> 8) & 0xFF  # High byte
+
+        # Checksum: XOR of bytes 0-6
+        cs = 0
+        for b in data[:-1]:
+            cs ^= b
+        data[7] = cs
+        
+        print(Packet.from_bytes(data))
+        return Packet.from_bytes(data)
+    
+def main():
+    handler = DistanceHandler(i2c_id=0, sda=0, scl=1, slave_addr=0x41, trig_pin=3, echo_pin=2)
+    print("Distance handler I2C slave started")
+    try:
+        handler.handle()
+    except KeyboardInterrupt:
+        handler.deinit()
+        print("I2C slave stopped")
+
+if __name__ == "__main__":
+    main()