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Communication Processor Module
16-338
MPC823 USER’S MANUAL
MOTOROLA
SCC2
COMMUNICATION
16
PROCESSOR
MODULE
module. The SCC2 Ethernet controller writes these bits after it finishes transmitting the
associated data buffer.
16.9.23.4 SCC2 ETHERNET EVENT REGISTER. When the SCC2 is in Ethernet mode,
the 16-bit memory-mapped SCC2 event register is referred to as the SCC2 Ethernet event
register (SCCE–Ethernet). Since each protocol has specific requirements, the SCCE bits
are different for each implementation. This register is used to generate interrupts and report
events recognized by the Ethernet channel. When an event is recognized, the SCC2
Ethernet controller sets the corresponding bit in the SCCE–Ethernet register. Interrupts
generated by this register can be masked in the SCCM–Ethernet register. An example of
interrupts that can be generated in the Ethernet protocol is illustrated in
Figure 16-108.A bit is cleared by writing a 1(writing a zero has no effect) and more than one bit can be
cleared at a time. All unmasked bits must be cleared before the communication processor
module clears the internal interrupt request. This register is cleared at reset and can be read
at any time.
Bits 0–7 and 9–10—Reserved
These bits are reserved and should be set to 0.
GRA—Graceful Stop Complete
This bit indicates that a graceful stop, initiated by the GRACEFUL STOP TRANSMIT
command, is now complete. This bit is set as soon the transmitter finishes any frame that
was in progress when the command was issued. It is set immediately if no frame was in
progress when the command was issued.
TXE—TX Error
This bit indicates that an error has occurred on the transmitter channel.
RXF—RX Frame
This bit indicates that a complete frame has been received on the Ethernet channel.
BSY—Busy Condition
This bit indicates when a frame is received and discarded due to a lack of buffers.
TXB—TX Buffer
This bit indicates that a buffer has been transmitted on the Ethernet channel.
SCCE–ETHERNET
BIT
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
FIELD
RESERVED
GRA RESERVED
TXE
RXF
BSY
TXB
RXB
RESET
0
00000
R/W
R/W
ADDR
(IMMR & 0xFFFF0000) + 0xA30