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GeezerVison is showing github.com — backend/coderbot/sonar.py at develop · CoderBotOrg/backend

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sonar.py

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import time
import pigpio
import logging
class Sonar:
"""
This class encapsulates a type of acoustic ranger. In particular
the type of ranger with separate trigger and echo pins.
A pulse on the trigger initiates the sonar ping and shortly
afterwards a sonar pulse is transmitted and the echo pin
goes high. The echo pins stays high until a sonar echo is
received (or the response times-out). The time between
the high and low edges indicates the sonar round trip time.
"""
MICROSECONDS = 1000000.0
SOUND_SPEED = 34030.0
ECHO_TIMEOUT = 0.1
def __init__(self, pi, trigger, echo):
"""
The class is instantiated with the Pi to use and the
gpios connected to the trigger and echo pins.
"""
self.pi = pi
self._trig = trigger
self._echo = echo
self._ping = False
self._high = None
self._time = None
self._triggered = False
self._trig_mode = pi.get_mode(self._trig)
self._echo_mode = pi.get_mode(self._echo)
pi.set_mode(self._trig, pigpio.OUTPUT)
pi.set_mode(self._echo, pigpio.INPUT)
self._cb = pi.callback(self._trig, pigpio.EITHER_EDGE, self._cbf)
self._cb = pi.callback(self._echo, pigpio.EITHER_EDGE, self._cbf)
self._inited = True
def _cbf(self, gpio, level, tick):
if gpio == self._trig and self._triggered == False:
if level == 0: # trigger sent
self._triggered = True
self._high = None
else:
if self._triggered:
if level == 1:
self._high = tick
else:
if self._high is not None:
self._time = tick - self._high
self._high = None
self._ping = True
self._triggered = False
def read(self):
"""
Triggers a reading. The returned reading is the number
of microseconds for the sonar round-trip.
round trip cms = round trip time / 1000000.0 * 34030
"""
if self._inited:
self._ping = False
self.pi.gpio_trigger(self._trig)
start = time.time()
while not self._ping:
if (time.time()-start) > self.ECHO_TIMEOUT:
return 20000
time.sleep(0.001)
return self._time
else:
return None
def get_distance(self):
time.sleep(0.05)
return round(self.read() / self.MICROSECONDS * self.SOUND_SPEED / 2, 1) # seconds / microseconds * sound speed / 2 (half trip)
def cancel(self):
"""
Cancels the sonars and returns the gpios to their
original mode.
"""
if self._inited:
self._inited = False
self._cb.cancel()
self.pi.set_mode(self._trig, self._trig_mode)
self.pi.set_mode(self._echo, self._echo_mode)
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