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Fixed Issue 13, Samsung EVO 32GB cards not working #19

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Fixed Issue 13, Samsung EVO 32GB cards not working #19

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e0e614e
Fixed Issue 13, Samsung EVO 32GB cards not working
Aug 5, 2019
bb5342b
adding dynamic CRC
Aug 7, 2019
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49 changes: 41 additions & 8 deletions adafruit_sdcard.py
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Original file line number Diff line number Diff line change
Expand Up @@ -153,7 +153,7 @@ def _init_card(self):
# get the number of sectors
# CMD9: response R2 (R1 byte + 16-byte block read)
csd = bytearray(16)
if self._cmd(9, response_buf=csd) != 0:
if self._cmd(9, 0, 0xaf, response_buf=csd) != 0:
raise OSError("no response from SD card")
#self.readinto(csd)
csd_version = (csd[0] & 0xc0) >> 6
Expand All @@ -169,7 +169,7 @@ def _init_card(self):
self._sectors = block_length // 512 * mult * (c_size + 1)

# CMD16: set block length to 512 bytes
if self._cmd(16, 512, 0) != 0:
if self._cmd(16, 512, 0x15) != 0:
raise OSError("can't set 512 block size")

# set to high data rate now that it's initialised
Expand All @@ -190,10 +190,10 @@ def _init_card_v2(self):
ocr = bytearray(4)
for _ in range(_CMD_TIMEOUT):
time.sleep(.050)
self._cmd(58, response_buf=ocr, data_block=False)
self._cmd(55)
if self._block_cmd(41, 0x200000, 0) == 0:
self._cmd(58, response_buf=ocr, data_block=False)
self._cmd(58, 0, 0xfd, response_buf=ocr, data_block=False)
self._cmd(55, 0, 0x65)
if self._cmd(41, 0x40000000, 0x77) == 0:
self._cmd(58, 0, 0xfd, response_buf=ocr, data_block=False)

# Check for block addressing
if (ocr[0] & 0x40) != 0:
Expand Down Expand Up @@ -234,6 +234,10 @@ def _cmd(self, cmd, arg=0, crc=0, response_buf=None, data_block=True, wait=True)
buf[2] = (arg >> 16) & 0xff
buf[3] = (arg >> 8) & 0xff
buf[4] = arg & 0xff
if (!crc):
buf[5] = calculate_crc(buf[:-1])
else:
buf[5] = crc
buf[5] = crc

with self._spi as spi:
Expand Down Expand Up @@ -281,7 +285,10 @@ def _block_cmd(self, cmd, block, crc, response_buf=None):
buf[2] = (block >> 7) & 0xff
buf[3] = (block << 1) & 0xff
buf[4] = 0
buf[5] = crc
if (!crc):
buf[5] = calculate_crc(buf[:-1])
else:
buf[5] = crc

result = -1
with self._spi as spi:
Expand Down Expand Up @@ -416,7 +423,7 @@ def readblocks(self, start_block, buf):
self._readinto(buf, start=offset, end=(offset + 512))
offset += 512
nblocks -= 1
return self._cmd(12, wait=False)
return self._cmd(12, 0, 0x61, wait=False)
return 0

def writeblocks(self, start_block, buf):
Expand Down Expand Up @@ -447,3 +454,29 @@ def writeblocks(self, start_block, buf):
nblocks -= 1
self._cmd_nodata(_TOKEN_STOP_TRAN, 0x0)
return 0

def calculate_crc(message):
# Code converted from https://github.com/hazelnusse/crc7/blob/master/crc7.cc by devoh747
# With permission from Dale Lukas Peterson <hazelnusse@gmail.com>
# 8/6/2019

CRCTable = bytearray(256)

CRCPoly = const(0x89) # the value of our CRC-7 polynomial

# generate a table value for all 256 possible byte values
for i in range(256):
if (i & 0x80):
CRCTable[i] = i ^ CRCPoly
else:
CRCTable[i] = i
for _ in range(1,8):
CRCTable[i] = CRCTable[i] << 1
if (CRCTable[i] & 0x80):
CRCTable[i] = CRCTable[i] ^ CRCPoly

CRC = 0
for i in range(len(message)):
CRC = CRCTable[(CRC << 1) ^ message[i]]

return ((CRC << 1) | 1)