lan91c100fd Standard Microsystems Corp., lan91c100fd Datasheet - Page 27

• Manufacturer Part Number: lan91c100fd
• Description: Lan91c100fd Rev. B Feast Fast Ethernet Controller With Full Duplex Capability
• Manufacturer: Standard Microsystems Corp.

BANK 1
RCV_BAD - When set, bad CRC packets are received. When clear bad CRC packets do not generate interrupts and their
memory is released. Note: nRXDISC, when asserted, overrides RCV_BAD. Also, RCV_ BAD does not modify the function
of RCV DISCARD in the early receive register.
AUTO RELEASE - When set, transmit pages are released by transmit completion if the transmission was successful (when
TX_SUC is set). In that case there is no status word associated with its packet number, and successful packet numbers are
not even written into the TX COMPLETION FIFO. A sequence of transmit packets will generate an interrupt only when the
sequence is completely transmitted (TX EMPTY INT will be set), or when a packet in the sequence experiences a fatal
error (TX INT will be set). Upon a fatal error TXENA is cleared and the transmission sequence stops. The packet number
that failed, is present in the FIFO PORTS register, and its pages are not released, allowing the CPU to restart the
sequence after corrective action is taken.
LE ENABLE - Link Error Enable. When set it enables the LINK_OK bit transition as one of the interrupts merged into the
EPH INT bit. Clearing the LE ENABLE bit after an EPH INT interrupt, caused by a LINK_OK transition, will acknowledge
the interrupt. LE ENABLE defaults low (disabled).
CR ENABLE - Counter Roll over Enable. When set, it enables the CTR_ROL bit as one of the interrupts merged into the
EPH INT bit. Reading the COUNTER register after an EPH INT interrupt caused by a counter rollover, will acknowledge the
interrupt. CR ENABLE defaults low (disabled).
TE ENABLE - Transmit Error Enable. When set it enables Transmit Error as one of the interrupts merged into the EPH INT
bit. An EPH INT interrupt caused by a transmitter error is acknowledged by setting TXENA bit in the TCR register to 1 or by
clearing the TE ENABLE bit. TE ENABLE defaults low (disabled). Transmit Error is any condition that clears TXENA with
TX_SUC staying low as described in the EPHSR register.
EEPROM SELECT - This bit allows the CPU to specify which registers the EEPROM RELOAD or STORE refers to. When
high, the General Purpose Register is the only register read or written. When low, RELOAD reads Configuration, Base and
Individual Address, and STORE writes the Configuration and Base registers.
RELOAD - When set it will read the EEPROM and update relevant registers with its contents. Clears upon completing the
operation.
STORE - When set, stores the contents of all relevant registers in the serial EEPROM. Clears upon completing the
operation.
Note: When an EEPROM access is in progress the STORE and RELOAD bits will be read back as high. The remaining 14
bits of this register will be invalid. During this time attempted read/write operations, other than polling the EEPROM status,
will NOT have any effect on the internal registers. The CPU can resume accesses to the LAN91C100FD after both bits are
low. A worst case RELOAD operation initiated by RESET or by software takes less than 750 µs.
SMSC DS – LAN91C100FD REV. B
OFFSET
HIGH
BYTE
BYTE
LOW
C
ENABLE
LE
0
0
0
CONTROL REGISTER
ENABLE
RCV_
BAD
CR
0
0
NAME
ENABLE
TE
0
0
0
Page 27
1
1
1
1
RELEAS
AUTO
READ/WRITE
E
0
0
0
TYPE
EEPROM
SELECT
0
0
0
RELOAD
1
1
0
SYMBOL
CTR
STORE
0
0
0
Rev. 03-28-07