updated ultrasonic sensor

mithru · mithru · commit 1b7c7c96be87 · 2014-08-20T19:28:16.000+08:00
diff --git a/08.Sensors/HC-SR04/boot.py b/08.Sensors/HC-SR04/boot.py
@@ -0,0 +1,3 @@
+import pyb
+
+import ultrasonic
diff --git a/08.Sensors/HC-SR04/main.py b/08.Sensors/HC-SR04/main.py
@@ -0,0 +1,31 @@
+# setting pins to accomodate Ultrasonic Sensor (HC-SR04)
+sensor1_trigPin = pyb.Pin.board.X3
+sensor1_echoPin = pyb.Pin.board.X4
+sensor2_trigPin = pyb.Pin.board.Y3
+sensor2_echoPin = pyb.Pin.board.Y4
+
+# sensor needs 5V and ground to be connected to pyboard's ground
+
+# creating two Ultrasonic Objects using the above pin config
+
+sensor1 = ultrasonic.Ultrasonic(sensor1_trigPin, sensor1_echoPin)
+sensor2 = ultrasonic.Ultrasonic(sensor2_trigPin, sensor2_echoPin)
+
+# using USR switch to print the sensor's values when pressed
+
+switch = pyb.Switch()
+
+# function that prints each sensor's distance
+def print_sensor_values():
+	# get sensor1's distance in cm
+	distance1 = sensor1.distance_in_cm()
+	# get sensor2's distance in inches
+	distance2 = sensor2.distance_in_inches()
+
+	print("Sensor1 (Metric System)", distance1, "cm")
+	print("Sensor2 (Imperial System)", distance2, "inches")
+
+# prints values every second
+while True:
+	print_sensor_values()
+	pyb.delay(1000)
diff --git a/08.Sensors/HC-SR04/ultrasonic.py b/08.Sensors/HC-SR04/ultrasonic.py
@@ -0,0 +1,72 @@
+##
+# Ultrasonic library for MicroPython's pyboard.
+# Compatible with HC-SR04 and SRF04.
+#
+# Copyright 2014 - Sergio Conde Gómez <skgsergio@gmail.com>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+##
+
+import pyb
+
+# Pin configuration.
+# WARNING: Do not use PA4-X5 or PA5-X6 as the echo pin without a 1k resistor.
+
+class Ultrasonic:
+    def __init__(self, tPin, ePin):
+        self.triggerPin = tPin
+        self.echoPin = ePin
+
+        # Init trigger pin (out)
+        self.trigger = pyb.Pin(self.triggerPin)
+        self.trigger.init(pyb.Pin.OUT_PP, pyb.Pin.PULL_NONE)
+        self.trigger.low()
+
+        # Init echo pin (in)
+        self.echo = pyb.Pin(self.echoPin)
+        self.echo.init(pyb.Pin.IN, pyb.Pin.PULL_NONE)
+
+    def distance_in_inches(self):
+        return (self.distance_in_cm() * 0.3937)
+
+    def distance_in_cm(self):
+        start = 0
+        end = 0
+
+        # Create a microseconds counter.
+        micros = pyb.Timer(2, prescaler=83, period=0x3fffffff)
+        micros.counter(0)
+
+        # Send a 10us pulse.
+        self.trigger.high()
+        pyb.udelay(10)
+        self.trigger.low()
+
+        # Wait 'till whe pulse starts.
+        while self.echo.value() == 0:
+            start = micros.counter()
+
+        # Wait 'till the pulse is gone.
+        while self.echo.value() == 1:
+            end = micros.counter()
+
+        # Deinit the microseconds counter
+        micros.deinit()
+
+        # Calc the duration of the recieved pulse, divide the result by
+        # 2 (round-trip) and divide it by 29 (the speed of sound is
+        # 340 m/s and that is 29 us/cm).
+        dist_in_cm = ((end - start) / 2) / 29
+
+        return dist_in_cm

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+import pyb`
	`2`	`+`
	`3`	`+import ultrasonic`