Communications Processor
MPC885 PowerQUICC Family Reference Manual, Rev. 2
18-10
Freescale Semiconductor
18.6.4.1
CP Command Examples
To completely reset the CPM, write 0x8001 to the CPCR. After the FLG bit has cleared, setup of the CPM
can continue. To execute
ENTER
HUNT
MODE
on SCC2, for example, write 0x0341 to the CPCR. While the
command is executing, the CPCR returns a 0x0341 value; after executing, it returns 0x0340.
18.6.4.2
CP Command Execution Latency
The worst-case command execution latency for the CP is 500 clocks, while the typical command execution
latency is about 40 clocks.
18.7
Dual-Port RAM
The CPM has 8 Kbytes of static RAM configured as dual-port memory, shown in
Figure 18-6
.
NOTE
The entire dual-port RAM should be cleared as the first step in system
initialization. This step should be followed by issuing a CPM reset using the
CPCR. Only after these two steps should the dual-port RAM be
programmed for specific CPM functions.
RESTART
TX
Restart transmission. After
STOP
TX
or
GRACEFUL
STOP
TX
,
RESTART
TX
starts the transmitter, which
begins polling the R bit of the current BD.
CLOSE
RX
BD
Closes the current RxBD in mid-reception; reception continues using the next available BD. Use
CLOSE
RX
BD
to access the data buffer without waiting for the SCC to finish filling it.
INIT
IDMA
Initialize IDMA transfers. Initializes the IDMA internal CP state to the user-defined reset value.
STOP
IDMA
Stop IDMA transfers. The CP terminates current IDMA transfers.
SET
TIMER
Used to activate, deactivate, or reconfigure the 16 timers of the RISC timer table.
SET
GROUP
ADDRESS
Sets a hash table bit for the Ethernet logical group address recognition function.
GCI
ABORT
REQUEST
GCI receiver sends an abort request.
GCI
TIMEOUT
Performs the GCI timeout function.
RESET
BCS
Used in BISYNC mode to reset the block check sequence calculation.
ATM
COMMANDS
See
Section 39.4, “Port-to-Port (PTP) Switching.”
USB
COMMAND
USB command code. The specific USB commands are described in
Section 31.13, “USB CP
Commands.”
U
Undefined. Reserved for use by Freescale-supplied RAM microcode packages.
Table 18-8. CP Commands (continued)
Command
Description
Summary of Contents for PowerQUICC MPC870
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