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Am79C930
TIR21: CRC32 Correct Byte Count MSB
This register is the CRC32 Correct Byte Count
MSB register.
Bit Name Reset Value Description
7–4 Reserved – Reserved. Must be written as a 0. Reads of this bit produce
undefined data.
3–0 C32C[11:8] – CRC32 Correct Count. The value in this register indicates the upper
4 bits of the 12-bit byte position when the CRC32 value was last cor-
rect. CRC32 value 001h corresponds to the first byte of the received
message following the Start of Frame Delimiter. If the value in this
register (and TIR20) does not match the length value indicated in
the frame header (plus overhead for PHY and MAC headers and
CRC) for frames that employ 32-bit CRC values, then the frame
should be rejected by the MAC firmware. Note that all bytes begin-
ning with the first byte following the Start of Frame Delimiter and in-
cluding the CRC bytes are included in the CRC32 Correct Count
value, but the bytes that are included in the CRC32 calculation are
dependent upon the setting of the PFL bits of TCR3.
TIR22: CRC8 Correct Byte Count LSB
This register is the CRC8 Correct Byte Count
LSB register.
Bit Name Reset Value Description
7–0 C32C[7:0] – CRC8 Correct Count. The value in this register indicates the lower 8
bits of the 12-bit byte position when the CRC8 value was last cor-
rect. CRC8 value 001h corresponds to the first byte of the received
message following the Start of Frame Delimiter. If the value in this
register (and TIR22) does not match the length value indicated in
the frame header (plus overhead for PHY and MAC headers and
CRC) for frames that employ 8-bit CRC values, then the frame
should be rejected by the MAC firmware. Note that all bytes begin-
ning with the first byte following the Start of Frame Delimiter and in-
cluding the CRC bytes are included in the CRC8 Correct Count
value, but the bytes that are included in the CRC8 calculation are
dependent upon the setting of the PFL bits of TCR3.
TIR23: CRC8 Correct Byte Count MSB
This register is the CRC8 Correct Byte Count
MSB register .
Bit Name Reset Value Description
7–4 Reserved – Reserved. Must be written as a 0. Reads of this bit produce
undefined data.
3–0 C8C[11:8] – CRC8 Correct Count. The value in this register indicates the upper
4 of the 12-bit byte position when the CRC8 value was last correct.
CRC8 value 001h corresponds to the first byte of the received mes-
sage following the Start of Frame Delimiter. If the value in this regis-
ter (and TIR22) does not match the length value indicated in the
frame header (plus overhead for PHY and MAC headers and CRC)
for frames that employ 8-bit CRC values, then the frame should be
rejected by the MAC firmware. Note that all bytes beginning with the
first byte following the Start of Frame Delimiter and including the
CRC bytes are included in the CRC8 Correct Count value, but the
bytes that are included in the CRC8 calculation are dependent upon
the setting of the PFL bits of TCR3.