LM3S8938 Datasheet, PDF (443/550 Pages) List of Unclassifed Manufacturers – Microcontroller

LM3S8938 Microcontroller
FIFO Word Read/Write
Sequence
4th
5th to nth
last
Word Bit Fields
7:0
15:8
23:16
31:24
7:0
15:8
23:16
31:24
7:0
15:8
23:16
31:24
TX FIFO (Write)
RX FIFO (Read)
SA oct 5
SA oct 6
Len/Type MSB
Len/Type LSB
data oct n
data oct n+1
data oct n+2
data oct n+3
FCS 1 (if CRC generation is FCS 1
disabled in MACTCTL)
FCS 2 (if CRC generation is FCS 2
disabled in MACTCTL)
FCS 3 (if CRC generation is FCS 3
disabled in MACTCTL)
FCS 4 (if CRC generation is FCS 4
disabled in MACTCTL)
17.2.3.3 Ethernet Transmission Options
The ethernet controller can automatically generate and insert the Frame Check Sequence (FCS)
at the end of the transmit frame. This is controlled by the CRC bit in the MACTCTL register. For test
purposes, in order to generate a frame with an invalid CRC, this feature can be disabled.
The IEEE 802.3 specification requires that the ethernet frame payload section be a minimum of 46
bytes. The ethernet controller can be configured to automatically pad the data section if the payload
data section loaded into the FIFO is less than the minimum 46 bytes. This feature is controlled by
the PADEN bit in the MACTCTL register.
At the MAC layer, the transmitter can be configured for both full-duplex and half-duplex operation
by using the DUPLEX bit in the MACTCTL register.
17.2.3.4 Ethernet Reception Options
Using the BADCRC bit in the MACRCTL register, the ethernet controller can be configured to reject
incoming ethernet frames with an invalid Frame Check Sequence field.
The ethernet receiver can also be configured for Promiscuous and Multicast modes using the PRMS
and AMUL fields in the MACRCTL register. If these modes are not enabled, only ethernet frames
with a broadcast address, or frames matching the MAC address programmed into the MACIA0 and
MACIA1 register will be placed into the RX FIFO.
17.2.4
Interrupts
The ethernet controller can generate an interrupt for one or more of the following conditions.
■ A frame has been received into an empty RX FIFO.
■ A frame transmission error has occurred
■ A frame has been transmitted successfully.
■ A frame has been received with no room in the RX FIFO (overrun).
June 14, 2007
443
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