pulled i2c into its own subclass
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ladyada
parent
aa36758493
commit
f1f0b7a13f
1 changed files with 71 additions and 46 deletions
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@ -148,22 +148,13 @@ class BusyError(Exception):
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"""Base class for exceptions in this module."""
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pass
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class PN532_I2C(object):
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"""PN532 breakout board representation. Requires a SPI connection to the
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breakout board. A software SPI connection is recommended as the hardware
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SPI on the Raspberry Pi has some issues with the LSB first mode used by the
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PN532 (see: http://www.raspberrypi.org/forums/viewtopic.php?f=32&t=98070&p=720659#p720659)
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"""
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class PN532:
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"""PN532 driver base, must be extended for I2C/SPI/UART interfacing"""
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def __init__(self, i2c, *, irq=None, reset=None, debug=False):
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"""Create an instance of the PN532 class using either software SPI (if
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the sclk, mosi, and miso pins are specified) or hardware SPI if a
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spi parameter is passed. The cs pin must be a digital GPIO pin.
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Optionally specify a GPIO controller to override the default that uses
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the board's GPIO pins.
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def __init__(self, *, debug=False, reset=None):
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"""Create an instance of the PN532 class
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"""
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self.debug = debug
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self._irq = irq
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if reset:
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print("resetting")
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reset.direction = Direction.OUTPUT
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@ -173,14 +164,29 @@ class PN532_I2C(object):
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time.sleep(0.1)
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reset.value = True
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time.sleep(1)
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self._i2c = i2c_device.I2CDevice(i2c, _I2C_ADDRESS)
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try:
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self.get_firmware_version() # first time often fails, try 2ce
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return
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except:
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pass
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self.get_firmware_version()
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def _read_data(self, count):
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# Read raw data from device, not including status bytes:
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# Subclasses MUST implement this!
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raise NotImplementedError
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def _write_data(self, framebytes):
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# Write raw bytestring data to device, not including status bytes:
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# Subclasses MUST implement this!
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raise NotImplementedError
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def _wait_ready(self, timeout):
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# Check if busy up to max length of 'timeout' seconds
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# Subclasses MUST implement this!
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raise NotImplementedError
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def _write_frame(self, data):
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"""Write a frame to the PN532 with the specified data bytearray."""
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assert data is not None and 0 < len(data) < 255, 'Data must be array of 1 to 255 bytes.'
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@ -207,21 +213,7 @@ class PN532_I2C(object):
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# Send frame.
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if self.debug:
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print('Write frame: ', [hex(i) for i in frame])
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with self._i2c:
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self._i2c.write(bytes(frame))
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def _read_data(self, count):
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"""Read a specified count of bytes from the PN532."""
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# Build a read request frame.
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frame = bytearray(count+1)
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with self._i2c:
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self._i2c.readinto(frame, end=1) # read ready byte!
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if frame[0] != 0x01: # not ready
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raise BusyError
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self._i2c.readinto(frame)
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if self.debug:
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print("Reading: ", [hex(i) for i in frame[1:]])
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return frame[1:]
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self._write_data(bytes(frame))
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def _read_frame(self, length):
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"""Read a response frame from the PN532 of at most length bytes in size.
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@ -255,21 +247,6 @@ class PN532_I2C(object):
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# Return frame data.
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return response[offset+2:offset+2+frame_len]
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def _wait_ready(self, timeout=1):
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if self._irq:
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print("TODO IRQ")
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else:
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status = bytearray(1)
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t = time.monotonic()
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while (time.monotonic() - t) < timeout:
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with self._i2c:
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self._i2c.readinto(status)
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if status == b'\x01':
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return True
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else:
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time.sleep(0.1)
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return True
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def call_function(self, command, response_length=0, params=[], timeout=1):
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"""Send specified command to the PN532 and expect up to response_length
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bytes back in a response. Note that less than the expected bytes might
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@ -400,4 +377,52 @@ class PN532_I2C(object):
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response = self.call_function(_COMMAND_INDATAEXCHANGE,
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params=params,
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response_length=1)
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return response[0] == 0x00
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return response[0] == 0x0
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class PN532_I2C(PN532):
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"""Driver for the PN532 connected over I2C."""
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def __init__(self, i2c, *, irq=None, reset=None, debug=False):
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"""Create an instance of the PN532 class using either software SPI (if
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the sclk, mosi, and miso pins are specified) or hardware SPI if a
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spi parameter is passed. The cs pin must be a digital GPIO pin.
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Optionally specify a GPIO controller to override the default that uses
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the board's GPIO pins.
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"""
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self.debug = debug
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self._irq = irq
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self._i2c = i2c_device.I2CDevice(i2c, _I2C_ADDRESS)
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super().__init__(debug=debug, reset=reset)
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def _wait_ready(self, timeout=1):
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if self._irq:
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print("TODO IRQ")
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else:
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status = bytearray(1)
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t = time.monotonic()
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while (time.monotonic() - t) < timeout:
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with self._i2c:
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self._i2c.readinto(status)
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if status == b'\x01':
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return True
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else:
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time.sleep(0.1)
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return True
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def _read_data(self, count):
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"""Read a specified count of bytes from the PN532."""
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# Build a read request frame.
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frame = bytearray(count+1)
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with self._i2c:
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self._i2c.readinto(frame, end=1) # read ready byte!
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if frame[0] != 0x01: # not ready
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raise BusyError
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self._i2c.readinto(frame)
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if self.debug:
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print("Reading: ", [hex(i) for i in frame[1:]])
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return frame[1:]
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def _write_data(self, framebytes):
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with self._i2c:
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self._i2c.write(framebytes)
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