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Make compatible with native adafruit_bus_device #43

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Merged
merged 2 commits into from
Feb 10, 2021
Merged

Make compatible with native adafruit_bus_device #43

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597dffe
Make compatible with native adafruit_bus_device
dhalbert Feb 9, 2021
bcc5b95
CS should be high during first initialization
dhalbert Feb 9, 2021
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40 changes: 13 additions & 27 deletions adafruit_sdcard.py
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Original file line number Diff line number Diff line change
Expand Up @@ -87,8 +87,7 @@ class SDCard:
"""

def __init__(self, spi, cs, baudrate=1320000):
# This is the init baudrate.
# We create a second device with the target baudrate after card initialization.
# Create an SPIDevice running at a lower initialization baudrate first.
self._spi = spi_device.SPIDevice(spi, cs, baudrate=250000, extra_clocks=8)

self._cmdbuf = bytearray(6)
Expand All @@ -97,29 +96,21 @@ def __init__(self, spi, cs, baudrate=1320000):
# Card is byte addressing, set to 1 if addresses are per block
self._cdv = 512

# initialise the card and switch to high speed
self._init_card(baudrate)
# initialise the card
self._init_card(cs)

def _clock_card(self, cycles=8):
"""
Clock the bus a minimum of `cycles` with the chip select high.

:param int cycles: The minimum number of clock cycles to cycle the bus.
"""
while not self._spi.spi.try_lock():
pass
self._spi.spi.configure(baudrate=self._spi.baudrate)
self._spi.chip_select.value = True
# Create a new SPIDevice with the (probably) higher operating baudrate.
self._spi = spi_device.SPIDevice(spi, cs, baudrate=baudrate, extra_clocks=8)

self._single_byte[0] = 0xFF
for _ in range(cycles // 8 + 1):
self._spi.spi.write(self._single_byte)
self._spi.spi.unlock()

def _init_card(self, baudrate):
def _init_card(self, chip_select):
"""Initialize the card in SPI mode."""
# clock card at least cycles with cs high
self._clock_card(80)
# clock card at least 80 cycles with cs high
with self._spi as card:
# Force CS high.
chip_select.value = True
self._single_byte[0] = 0xFF
for _ in range(80 // 8 + 1):
card.write(self._single_byte)

with self._spi as card:
# CMD0: init card; should return _R1_IDLE_STATE (allow 5 attempts)
Expand Down Expand Up @@ -161,11 +152,6 @@ def _init_card(self, baudrate):
if self._cmd(card, 16, 512, 0x15) != 0:
raise OSError("can't set 512 block size")

# set to high data rate now that it's initialised
self._spi = spi_device.SPIDevice(
self._spi.spi, self._spi.chip_select, baudrate=baudrate, extra_clocks=8
)

def _init_card_v1(self, card):
"""Initialize v1 SDCards which use byte addressing."""
for _ in range(_CMD_TIMEOUT):
Expand Down