10.2 CLA Interface
This section describes how the C28x main CPU can interface to the CLA and conversely.
10.2.1 CLA Memory
The CLA can access three types of memory: program, data and message RAMs. The behavior and arbitration
for each type of memory is described in this chapter. The CLA RAMs are protected by the CSM module. Refer
to the Code Security Module (CSM) section of the
System Control and Interrupts
chapter for more details on the
security scheme.
•
CLA Program Memory
The CLA program can be loaded to a designated memory block. At reset, all memory blocks are mapped
to the CPU. While mapped to the CPU space, the CPU can copy the CLA program code into the memory.
During debug, the memory can also be loaded directly by the Code Composer Studio
™
IDE.
Once the memory is initialized with CLA code, the CPU maps it to the CLA program space by setting the
MMEMCFG[PROGE] bit.
When a memory block is configured as CLA program memory, debug accesses are allowed only on cycles
where the CLA is not fetching a new instruction. A detailed explanation of the memory configurations and
access arbitration (CPU, CLA, and DEBUG) process can be found in the Memory Controller Module section
of the
System Control and Interrupts
chapter.
All CLA program fetches are performed as 32-bit read operations and all opcodes must be aligned to an even
address. Since all CLA opcodes are 32-bits, this alignment occurs naturally.
•
CLA Data Memory
Designated memory locations can serve as data memory blocks to the CLA. At reset, all blocks are mapped
to the CPU memory space, whereby the CPU can initialize the memory with data tables, coefficients, and so
on, for the CLA to use.
Once the memory is initialized with CLA data, the CPU maps it to the CLA data space by setting the
respective MMEMCFG[RAMxE] bit.
When a memory block is configured as CLA data memory, CLA read and write accesses are arbitrated along
with CPU accesses. The user has the option of turning on CPU fetch or write protection to the memory by
writing to the appropriate MMEMCFG[RAMnCPUE] bits . A detailed explanation of the memory configurations
and access arbitration (CPU, CLA, and DEBUG) process can be found in the Memory Controller Module
section of the
System Control and Interrupts
chapter.
•
CLA Shared Message RAMs
There are two memory blocks for data sharing and communication between the CLA and the CPU . The
message RAMs are always mapped to both CPU and CLA memory spaces, and only data access is allowed;
no program fetches can be performed.
–
CLA to CPU Message RAM:
The CLA can use this block to pass data to the CPU. This block is both
readable and writable by the CLA. This block is also readable by the CPU but writes by the CPU are
ignored.
–
CPU to CLA Message RAM:
The CPU can use this block to pass data and messages to the CLA. This
message RAM is both readable and writable by the CPU. The CLA can perform reads but writes by the
CLA are ignored.
Control Law Accelerator (CLA)
572
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
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