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60 lines
1.8 KiB
Python
60 lines
1.8 KiB
Python
import ustruct
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import time
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class PCA9685:
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def __init__(self, i2c, address=0x40):
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self.i2c = i2c
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self.address = address
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self.reset()
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def _write(self, address, value):
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self.i2c.writeto_mem(self.address, address, bytearray([value]))
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def _read(self, address):
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return self.i2c.readfrom_mem(self.address, address, 1)[0]
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def reset(self):
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self._write(0x00, 0x00) # Mode1
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def freq(self, freq=None):
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if freq is None:
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return int(25000000.0 / 4096 / (self._read(0xfe) - 0.5))
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prescale = int(25000000.0 / 4096.0 / freq + 0.5)
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old_mode = self._read(0x00) # Mode 1
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self._write(0x00, (old_mode & 0x7F) | 0x10) # Mode 1, sleep
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self._write(0xfe, prescale) # Prescale
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self._write(0x00, old_mode) # Mode 1
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time.sleep_us(5)
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self._write(0x00, old_mode | 0xa1) # Mode 1, autoincrement on
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def pwm(self, index, on=None, off=None):
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if on is None or off is None:
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data = self.i2c.readfrom_mem(self.address, 0x06 + 4 * index, 4)
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return ustruct.unpack('<HH', data)
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data = ustruct.pack('<HH', on, off)
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self.i2c.writeto_mem(self.address, 0x06 + 4 * index, data)
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def duty(self, index, value=None, invert=False):
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if value is None:
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pwm = self.pwm(index)
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if pwm == (0, 4096):
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value = 0
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elif pwm == (4096, 0):
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value = 4095
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value = pwm[1]
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if invert:
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value = 4095 - value
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return value
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if not 0 <= value <= 4095:
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raise ValueError("Out of range")
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if invert:
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value = 4095 - value
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if value == 0:
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self.pwm(index, 0, 4096)
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elif value == 4095:
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self.pwm(index, 4096, 0)
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else:
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self.pwm(index, 0, value)
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