# The MIT License (MIT)
#
# Copyright (c) 2016 Scott Shawcroft for 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.
# pylint: disable=too-few-public-methods
"""
`adafruit_bus_device.spi_device` - SPI Bus Device
====================================================
"""
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BusDevice.git"
[docs]class SPIDevice:
"""
Represents a single SPI device and manages locking the bus and the device
address.
:param ~busio.SPI spi: The SPI bus the device is on
:param ~digitalio.DigitalInOut chip_select: The chip select pin object that implements the
DigitalInOut API.
:param int extra_clocks: The minimum number of clock cycles to cycle the bus after CS is high.
(Used for SD cards.)
.. note:: This class is **NOT** built into CircuitPython. See
:ref:`here for install instructions <bus_device_installation>`.
Example:
.. code-block:: python
import busio
import digitalio
from board import *
from adafruit_bus_device.spi_device import SPIDevice
with busio.SPI(SCK, MOSI, MISO) as spi_bus:
cs = digitalio.DigitalInOut(D10)
device = SPIDevice(spi_bus, cs)
bytes_read = bytearray(4)
# The object assigned to spi in the with statements below
# is the original spi_bus object. We are using the busio.SPI
# operations busio.SPI.readinto() and busio.SPI.write().
with device as spi:
spi.readinto(bytes_read)
# A second transaction
with device as spi:
spi.write(bytes_read)
"""
def __init__(self, spi, chip_select=None, *,
baudrate=100000, polarity=0, phase=0, extra_clocks=0):
self.spi = spi
self.baudrate = baudrate
self.polarity = polarity
self.phase = phase
self.extra_clocks = extra_clocks
self.chip_select = chip_select
if self.chip_select:
self.chip_select.switch_to_output(value=True)
def __enter__(self):
while not self.spi.try_lock():
pass
self.spi.configure(baudrate=self.baudrate, polarity=self.polarity,
phase=self.phase)
if self.chip_select:
self.chip_select.value = False
return self.spi
def __exit__(self, *exc):
if self.chip_select:
self.chip_select.value = True
if self.extra_clocks > 0:
buf = bytearray(1)
buf[0] = 0xff
clocks = self.extra_clocks // 8
if self.extra_clocks % 8 != 0:
clocks += 1
for _ in range(clocks):
self.spi.write(buf)
self.spi.unlock()
return False