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TC1796
System Units (Vol. 1 of 2)
On-Chip System Buses and Bus Bridges
User’s Manual
6-2
V2.0, 2007-07
Buses, V2.0
The SPB is accessible by the CPU via the LFI Bridge.
The RPB connects the peripherals with high data rates (SSC, ADC, FADC) to the Dual-
port memory (DPRAM) in the DMI, relieving the SPB and the two LMBs from these data
transfers. The RPB is controlled by a bus switch which is located in the DMA controller.
The two LMBs (PLMB and DLMB) run at CPU clock speed
f
CPU
, whereas SPB and RPB
run at system clock speed
f
SYS
. Note that
f
SYS
can be equal to
f
CPU
or half the
f
CPU
frequency, but
f
SYS
is limited to max. 75 MHz.
6.1
Program and Data Local Memory Buses
The PLMB and DLMB are identical LMBs especially designed for the 32-bit TriCore
system technology. Both buses operate in the same manner. The following terminology
is used for these buses:
6.1.1
Overview
The LMB is a synchronous and pipelined bus with variable block size transfer support.
The protocol supports 8-, 16-, 32-, and 64-bit single transactions and 2/4 wide 64-bit
block transfers.
The LMB has the following features:
•
Optimized for high speed and high performance data transfers
•
32-bit address bus, 64-bit data bus
•
Simple central arbitration per cycle
•
Slave-controlled wait state insertion
•
Address pipelining (max depth - 2)
•
Support of atomic operations LDMST, ST.T and SWAP.W
•
Block transfers with variable block length (two or four 64-bit data transactions)
Table 6-1
LMB Terms
Term
Description
Agent
An LMB agent is any master or slave device which is connected to
the LMB.
Master
An LMB master device is an LMB agent which is able to initiate
transactions on the LMB. It is also able to react as a LMB slave.
Slave
An LMB slave device is an LMB agent which is not able to initiate
transactions on the LMB. It is only able to handle operations that
are dedicated to it by a LMB master device.