mirror of https://github.com/joan2937/pigpio
115 lines
2.8 KiB
Python
Executable File
115 lines
2.8 KiB
Python
Executable File
#!/usr/bin/env python
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import time
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import pigpio
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class ranger:
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"""
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This class encapsulates a type of acoustic ranger. In particular
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the type of ranger with separate trigger and echo pins.
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A pulse on the trigger initiates the sonar ping and shortly
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afterwards a sonar pulse is transmitted and the echo pin
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goes high. The echo pins stays high until a sonar echo is
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received (or the response times-out). The time between
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the high and low edges indicates the sonar round trip time.
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"""
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def __init__(self, pi, trigger, echo):
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"""
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The class is instantiated with the Pi to use and the
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gpios connected to the trigger and echo pins.
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"""
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self.pi = pi
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self._trig = trigger
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self._echo = echo
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self._ping = False
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self._high = None
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self._time = None
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self._triggered = False
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self._trig_mode = pi.get_mode(self._trig)
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self._echo_mode = pi.get_mode(self._echo)
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pi.set_mode(self._trig, pigpio.OUTPUT)
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pi.set_mode(self._echo, pigpio.INPUT)
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self._cb = pi.callback(self._trig, pigpio.EITHER_EDGE, self._cbf)
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self._cb = pi.callback(self._echo, pigpio.EITHER_EDGE, self._cbf)
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self._inited = True
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def _cbf(self, gpio, level, tick):
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if gpio == self._trig:
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if level == 0: # trigger sent
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self._triggered = True
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self._high = None
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else:
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if self._triggered:
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if level == 1:
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self._high = tick
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else:
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if self._high is not None:
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self._time = tick - self._high
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self._high = None
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self._ping = True
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def read(self):
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"""
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Triggers a reading. The returned reading is the number
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of microseconds for the sonar round-trip.
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round trip cms = round trip time / 1000000.0 * 34030
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"""
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if self._inited:
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self._ping = False
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self.pi.gpio_trigger(self._trig)
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start = time.time()
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while not self._ping:
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if (time.time()-start) > 5.0:
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return 20000
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time.sleep(0.001)
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return self._time
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else:
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return None
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def cancel(self):
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"""
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Cancels the ranger and returns the gpios to their
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original mode.
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"""
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if self._inited:
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self._inited = False
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self._cb.cancel()
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self.pi.set_mode(self._trig, self._trig_mode)
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self.pi.set_mode(self._echo, self._echo_mode)
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if __name__ == "__main__":
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import time
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import pigpio
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import sonar_trigger_echo
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pi = pigpio.pi()
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sonar = sonar_trigger_echo.ranger(pi, 23, 18)
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end = time.time() + 600.0
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r = 1
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while time.time() < end:
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print("{} {}".format(r, sonar.read()))
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r += 1
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time.sleep(0.03)
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sonar.cancel()
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pi.stop()
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