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micropython/drivers/sdcard.py: Add CRC7 values for SDCard.cmd() function calls #992

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micropython/drivers/sdcard.py: Add CRC7 values for SDCard.cmd() function calls #992

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3ddee7c
Add CRC7 values for SDCard.cmd() function calls
multicoder9 Mar 29, 2025
d5f76e6
micropython/drivers/storage/sdcard/sdcard.py: Added 0x7F CRC for two …
multicoder9 Mar 31, 2025
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40 changes: 27 additions & 13 deletions micropython/drivers/storage/sdcard/sdcard.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,20 @@
_TOKEN_STOP_TRAN = const(0xFD)
_TOKEN_DATA = const(0xFE)

## This function computes crc7 for SDcard commands
## It is not optimized, so do not call it where performance is critical
## You should usually be precomputing these values and hardcode them
#def crc7( cmd:bytes ):
# crc = 0
# for value in cmd:
# for i in range(8):
# crc <<= 1
# if (value&0x80)^(crc&0x80):
# crc ^= 0x09
# value <<= 1
# return ((crc<<1)|1)&0xFF
#def cmd_args_to_bytes( cmd:int, args:int ):
# return bytes( [cmd|0x40,(args>>24)&0xFF,(args>>16)&0xFF,(args>>8)&0xFF,args&0xFF] )

class SDCard:
def __init__(self, spi, cs, baudrate=1320000):
Expand Down Expand Up @@ -92,7 +106,7 @@ def init_card(self, baudrate):

# get the number of sectors
# CMD9: response R2 (R1 byte + 16-byte block read)
if self.cmd(9, 0, 0, 0, False) != 0:
if self.cmd(9, 0, 0xAF, 0, False) != 0:
raise OSError("no response from SD card")
csd = bytearray(16)
self.readinto(csd)
Expand All @@ -109,7 +123,7 @@ def init_card(self, baudrate):
# print('sectors', self.sectors)

# 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 @@ -118,8 +132,8 @@ def init_card(self, baudrate):
def init_card_v1(self):
for i in range(_CMD_TIMEOUT):
time.sleep_ms(50)
self.cmd(55, 0, 0)
if self.cmd(41, 0, 0) == 0:
self.cmd(55, 0, 0x65)
if self.cmd(41, 0, 0xE5) == 0:
# SDSC card, uses byte addressing in read/write/erase commands
self.cdv = 512
# print("[SDCard] v1 card")
Expand All @@ -129,10 +143,10 @@ def init_card_v1(self):
def init_card_v2(self):
for i in range(_CMD_TIMEOUT):
time.sleep_ms(50)
self.cmd(58, 0, 0, 4)
self.cmd(55, 0, 0)
if self.cmd(41, 0x40000000, 0) == 0:
self.cmd(58, 0, 0, -4) # 4-byte response, negative means keep the first byte
self.cmd(58, 0, 0xFD, 4)
self.cmd(55, 0, 0x65)
if self.cmd(41, 0x40000000, 0x77) == 0:
self.cmd(58, 0, 0xFD, -4) # 4-byte response, negative means keep the first byte
ocr = self.tokenbuf[0] # get first byte of response, which is OCR
if not ocr & 0x40:
# SDSC card, uses byte addressing in read/write/erase commands
Expand Down Expand Up @@ -250,15 +264,15 @@ def readblocks(self, block_num, buf):
assert nblocks and not len(buf) % 512, "Buffer length is invalid"
if nblocks == 1:
# CMD17: set read address for single block
if self.cmd(17, block_num * self.cdv, 0, release=False) != 0:
if self.cmd(17, block_num * self.cdv, 0x7F, release=False) != 0:
# release the card
self.cs(1)
raise OSError(5) # EIO
# receive the data and release card
self.readinto(buf)
else:
# CMD18: set read address for multiple blocks
if self.cmd(18, block_num * self.cdv, 0, release=False) != 0:
if self.cmd(18, block_num * self.cdv, 0x7F, release=False) != 0:
# release the card
self.cs(1)
raise OSError(5) # EIO
Expand All @@ -269,7 +283,7 @@ def readblocks(self, block_num, buf):
self.readinto(mv[offset : offset + 512])
offset += 512
nblocks -= 1
if self.cmd(12, 0, 0xFF, skip1=True):
if self.cmd(12, 0, 0x61, skip1=True):
raise OSError(5) # EIO

def writeblocks(self, block_num, buf):
Expand All @@ -281,14 +295,14 @@ def writeblocks(self, block_num, buf):
assert nblocks and not err, "Buffer length is invalid"
if nblocks == 1:
# CMD24: set write address for single block
if self.cmd(24, block_num * self.cdv, 0) != 0:
if self.cmd(24, block_num * self.cdv, 0x7F) != 0:
raise OSError(5) # EIO

# send the data
self.write(_TOKEN_DATA, buf)
else:
# CMD25: set write address for first block
if self.cmd(25, block_num * self.cdv, 0) != 0:
if self.cmd(25, block_num * self.cdv, 0x7F) != 0:
raise OSError(5) # EIO
# send the data
offset = 0
Expand Down
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