initial refactor

adafruit_pn532/spi.py

@@ -0,0 +1,120 @@
+# Adafruit PN532 NFC/RFID control library.
+# Author: Tony DiCola
+#
+# The MIT License (MIT)
+#
+# Copyright (c) 2015-2018 Adafruit Industries
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+"""
+``adafruit_pn532.spi``
+====================================================
+
+This module will let you communicate with a PN532 RFID/NFC shield or breakout
+using SPI.
+
+* Author(s): Original Raspberry Pi code by Tony DiCola, CircuitPython by ladyada,
+             refactor by Carter Nelson
+
+"""
+
+__version__ = "0.0.0-auto.0"
+__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_PN532.git"
+
+import time
+from adafruit_pn532.adafruit_pn532 import PN532 
+import adafruit_bus_device.spi_device as spi_device
+
+from micropython import const
+
+_SPI_STATREAD                  = const(0x02)
+_SPI_DATAWRITE                 = const(0x01)
+_SPI_DATAREAD                  = const(0x03)
+_SPI_READY                     = const(0x01)
+
+def reverse_bit(num):
+    """Turn an LSB byte to an MSB byte, and vice versa. Used for SPI as
+    it is LSB for the PN532, but 99% of SPI implementations are MSB only!"""
+    result = 0
+    for _ in range(8):
+        result <<= 1
+        result += (num & 1)
+        num >>= 1
+    return result
+
+class PN532_SPI(PN532):
+    """Driver for the PN532 connected over SPI. Pass in a hardware or bitbang
+    SPI device & chip select digitalInOut pin. Optional IRQ pin (not used),
+    reset pin and debugging output."""
+    def __init__(self, spi, cs_pin, *, irq=None, reset=None, debug=False):
+        """Create an instance of the PN532 class using SPI"""
+        self.debug = debug
+        self._irq = irq
+        self._spi = spi_device.SPIDevice(spi, cs_pin)
+        super().__init__(debug=debug, reset=reset)
+
+    def _wakeup(self):
+        """Send any special commands/data to wake up PN532"""
+        with self._spi as spi:
+            time.sleep(1)
+            spi.write(bytearray([0x00])) #pylint: disable=no-member
+            time.sleep(1)
+
+    def _wait_ready(self, timeout=1):
+        """Poll PN532 if status byte is ready, up to `timeout` seconds"""
+        status = bytearray([reverse_bit(_SPI_STATREAD), 0])
+
+        timestamp = time.monotonic()
+        while (time.monotonic() - timestamp) < timeout:
+            with self._spi as spi:
+                time.sleep(0.02)   # required
+                spi.write_readinto(status, status) #pylint: disable=no-member
+            if reverse_bit(status[1]) == 0x01:  # LSB data is read in MSB
+                return True      # Not busy anymore!
+            else:
+                time.sleep(0.01)  # pause a bit till we ask again
+        # We timed out!
+        return False
+
+    def _read_data(self, count):
+        """Read a specified count of bytes from the PN532."""
+        # Build a read request frame.
+        frame = bytearray(count+1)
+        # Add the SPI data read signal byte, but LSB'ify it
+        frame[0] = reverse_bit(_SPI_DATAREAD)
+
+        with self._spi as spi:
+            time.sleep(0.02)   # required
+            spi.write_readinto(frame, frame) #pylint: disable=no-member
+        for i, val in enumerate(frame):
+            frame[i] = reverse_bit(val) # turn LSB data to MSB
+        if self.debug:
+            print("Reading: ", [hex(i) for i in frame[1:]])
+        return frame[1:]
+
+    def _write_data(self, framebytes):
+        """Write a specified count of bytes to the PN532"""
+        # start by making a frame with data write in front,
+        # then rest of bytes, and LSBify it
+        rev_frame = [reverse_bit(x) for x in bytes([_SPI_DATAWRITE]) + framebytes]
+        if self.debug:
+            print("Writing: ", [hex(i) for i in rev_frame])
+        with self._spi as spi:
+            time.sleep(0.02)   # required
+            spi.write(bytes(rev_frame)) #pylint: disable=no-member