76 lines
2.3 KiB
Python
76 lines
2.3 KiB
Python
#!/usr/bin/python
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import math
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import time
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import smbus
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# ============================================================================
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# Raspi PCA9685 16-Channel PWM Servo Driver
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# ============================================================================
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class PCA9685:
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# Registers/etc.
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__SUBADR1 = 0x02
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__SUBADR2 = 0x03
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__SUBADR3 = 0x04
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__MODE1 = 0x00
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__PRESCALE = 0xFE
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__LED0_ON_L = 0x06
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__LED0_ON_H = 0x07
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__LED0_OFF_L = 0x08
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__LED0_OFF_H = 0x09
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__ALLLED_ON_L = 0xFA
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__ALLLED_ON_H = 0xFB
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__ALLLED_OFF_L = 0xFC
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__ALLLED_OFF_H = 0xFD
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def __init__(self, address=0x40, debug=False):
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self.bus = smbus.SMBus(1)
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self.address = address
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self.debug = debug
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self.write(self.__MODE1, 0x00)
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def write(self, reg, value):
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"Writes an 8-bit value to the specified register/address"
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self.bus.write_byte_data(self.address, reg, value)
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def read(self, reg):
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"Read an unsigned byte from the I2C device"
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result = self.bus.read_byte_data(self.address, reg)
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return result
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def setPWMFreq(self, freq):
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"Sets the PWM frequency"
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prescaleval = 25000000.0 # 25MHz
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prescaleval /= 4096.0 # 12-bit
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prescaleval /= float(freq)
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prescaleval -= 1.0
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oldmode = self.read(self.__MODE1)
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newmode = (oldmode & 0x7F) | 0x10 # sleep
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self.write(self.__MODE1, newmode) # go to sleep
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self.write(self.__PRESCALE, int(round(prescaleval)))
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self.write(self.__MODE1, oldmode)
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time.sleep(0.005)
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self.write(self.__MODE1, oldmode | 0x80)
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def setPWM(self, channel, on, off):
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"Sets a single PWM channel"
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self.write(self.__LED0_ON_L + 4 * channel, on & 0xFF)
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self.write(self.__LED0_ON_H + 4 * channel, on >> 8)
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self.write(self.__LED0_OFF_L + 4 * channel, off & 0xFF)
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self.write(self.__LED0_OFF_H + 4 * channel, off >> 8)
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def setMotorPwm(self, channel, duty):
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self.setPWM(channel, 0, duty)
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def setServoPulse(self, channel, pulse):
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"Sets the Servo Pulse,The PWM frequency must be 50HZ"
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pulse = float(pulse) * (4096.0 / 20000.0) # PWM frequency is 50HZ,the period is 20000us
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self.setPWM(channel, 0, int(pulse))
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if __name__ == '__main__':
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pass
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