MicroPython_PN532/adafruit_pn532/uart.py
2021-01-14 11:45:11 -05:00

69 lines
2.1 KiB
Python

# SPDX-FileCopyrightText: 2015-2018 Tony DiCola for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""
``adafruit_pn532.uart``
====================================================
This module will let you communicate with a PN532 RFID/NFC shield or breakout
using UART.
* 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, BusyError
class PN532_UART(PN532):
"""Driver for the PN532 connected over Serial UART"""
def __init__(self, uart, *, reset=None, debug=False):
"""Create an instance of the PN532 class using Serial connection.
Optional reset pin and debugging output.
"""
self.debug = debug
self._uart = uart
super().__init__(debug=debug, reset=reset)
def _wakeup(self):
"""Send any special commands/data to wake up PN532"""
if self._reset_pin:
self._reset_pin.value = True
time.sleep(0.01)
self.low_power = False
self._uart.write(
b"\x55\x55\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
) # wake up!
self.SAM_configuration()
def _wait_ready(self, timeout=1):
"""Wait `timeout` seconds"""
timestamp = time.monotonic()
while (time.monotonic() - timestamp) < timeout:
if self._uart.in_waiting > 0:
return True # No Longer Busy
time.sleep(0.01) # lets ask again soon!
# Timed out!
return False
def _read_data(self, count):
"""Read a specified count of bytes from the PN532."""
frame = self._uart.read(count)
if not frame:
raise BusyError("No data read from PN532")
if self.debug:
print("Reading: ", [hex(i) for i in frame])
return frame
def _write_data(self, framebytes):
"""Write a specified count of bytes to the PN532"""
self._uart.reset_input_buffer()
self._uart.write(framebytes)