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Fix: RuntimeError: CRC Mismatch / ATECC608A not reachable via I2C anymore #19

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Merged
merged 8 commits into from
Feb 26, 2021
Merged

Fix: RuntimeError: CRC Mismatch / ATECC608A not reachable via I2C anymore #19

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4d9addf
- Added documentation for config bytes
rrottmann Feb 25, 2021
d3e6401
- Making pylint happy
rrottmann Feb 26, 2021
61bd4b6
- Making pylint happy
rrottmann Feb 26, 2021
f05260a
Merge remote-tracking branch 'origin/master'
rrottmann Feb 26, 2021
a6bb6ca
Make pylint happy.
rrottmann Feb 26, 2021
88ef369
Make black happy.
rrottmann Feb 26, 2021
3718158
Fixed typo.
rrottmann Feb 26, 2021
5eacdce
Fixed binary representation.
rrottmann Feb 26, 2021
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69 changes: 67 additions & 2 deletions adafruit_atecc/adafruit_atecc.py
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Original file line number Diff line number Diff line change
Expand Up @@ -52,8 +52,20 @@
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_ATECC.git"


def _convert_i2c_addr_to_atecc_addr(i2c_addr=0x60):
int(i2c_addr, 16)
return i2c_addr << 1


# Device Address
_REG_ATECC_ADDR = const(0xC0)
_I2C_ADDR = 0x60
_REG_ATECC_ADDR = _convert_i2c_addr_to_atecc_addr(i2c_addr=_I2C_ADDR)

# TODO: Verify that _REG_ATECC_ADDR is still 0xC0
# TODO: Remove assertion test afterwards
assert _REG_ATECC_ADDR == 0xC0

_REG_ATECC_DEVICE_ADDR = _REG_ATECC_ADDR >> 1

# Version Registers
Expand Down Expand Up @@ -88,7 +100,6 @@
OP_WRITE: const(26),
}


CFG_TLS = b"\x01#\x00\x00\x00\x00P\x00\x00\x00\x00\x00\x00\xc0q\x00 \
\xc0\x00U\x00\x83 \x87 \x87 \x87/\x87/\x8f\x8f\x9f\x8f\xaf \
\x8f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 \
Expand All @@ -98,6 +109,60 @@
\x003\x003\x003\x003\x00\x1c\x00\x1c\x00\x1c\x00<\x00<\x00<\x00< \
\x00<\x00<\x00<\x00\x1c\x00"

"""
Configuration Zone Bytes

Serial Number (Bytes 0-3 and 8-12), Revision Number (Bytes 4-7)
AES Enable (Byte 13), I2C Enable (Byte 14), Reserved (Byte 15)
I2C Address (Byte 16), Reserved (Byte 17); Count Match (Byte 18)
Chip Mode (Byte 19), Slot Config (Bytes 20-51)
Counter 0 (Bytes 52-59), Counter 1 (Bytes 60-67)
Use Lock (Byte 68), Volatile Key Permission (Byte 69)
Secure Boot (Bytes 70-71), KDF (Bytes 72-74)
Reserved (Bytes 75-83), User Extra (Bytes 84-85)
Lock Config (Bytes 86-89), Chip Options (Bytes 90-91)
X509 (Bytes 92-95), Key Config (Bytes 96-127)

I2C Config

HEX DEC BIN Description
Byte 14: C0 192 1100 0000
^xxx xxxx Bit 0 (MSB): 0:Single Wire, 1:I2C; Bit 1-7: Set by Microchip
Byte 16: C0 192 1100 0000 Default 7 bit I2C Address: 0xC0>>1: 0x60 ATECC608A-MAHDA
Byte 16: 6A 106 0110 1010 Default 7 bit I2C Address: 0x6A>>1: 0x35 ATECC608A-TNGTLS
Byte 16: 20 32 0010 0000 Default 7 bit I2C Address: 0x20>>1: 0x10 ATECC608A-UNKNOWN
"""
CFG_TLS_HEX = bytes(
bytearray.fromhex(
"01 23 00 00 00 00 50 00 00 00 00 00 00 c0 71 00"
"20 20 20 20 20 20 20 20 20 20 20 20 20 c0 00 55"
"00 83 20 87 20 87 20 87 2f 87 2f 8f 8f 9f 8f af"
"20 20 20 20 20 20 20 20 20 20 20 20 20 8f 00 00"
"00 00 00 00 00 00 00 00 00 00 00 00 20 20 20 20"
"20 20 20 20 20 20 20 20 20 af 8f ff ff ff ff 00"
"00 00 00 ff ff ff ff 00 20 20 20 20 20 20 20 20"
"20 20 20 20 20 00 00 00 ff ff ff ff ff ff ff ff"
"ff ff ff ff 20 20 20 20 20 20 20 20 20 20 20 20"
"20 ff ff ff ff 00 00 55 55 ff ff 00 00 00 00 00"
"00 33 20 20 20 20 20 20 20 20 20 20 20 20 20 00"
"33 00 33 00 33 00 33 00 1c 00 1c 00 1c 00 3c 00"
"3c 00 3c 00 3c 20 20 20 20 20 20 20 20 20 20 20"
"20 20 00 3c 00 3c 00 3c 00 1c 00"
)
)

# TODO: Verify that both representations are identical
# TODO: Decide whether to use alternate representation of config bytes
# TODO: Remove assertion tests
assert CFG_TLS == CFG_TLS_HEX
assert bytearray(CFG_TLS)[16] == 0x20

# Convert I2C address to config byte 16 and update CFG_TLS
_CFG_BYTES = bytearray(CFG_TLS)
_CFG_BYTE_16 = hex(_I2C_ADDR << 1)
_CFG_BYTES[16] = ord(_CFG_BYTE_16)
CFG_TLS = bytes(_CFG_BYTES)


class ATECC:
"""
Expand Down