Flash Pipeline
CPU
32 bits
M
U
X
Data read from either program or data memory
Instruction Fetch
(64 bits)
Flash or OTP
Read
16 bits
Flash and OTP
Instruction buffer
64-bit
Buffer
64-bit
Buffer
Figure 1-2. Flash Pipeline
The flash pipeline pre-fetch is aborted only on a PC discontinuity caused by executing an instruction such as a
branch, BANZ, call, or loop. When this occurs, the pre-fetch is aborted and the contents of the pre-fetch buffer
are flushed. There are two possible scenarios when this occurs:
1. If the destination address is within the flash or OTP, the pre-fetch aborts and then resumes at the destination
address.
2. If the destination address is outside of the flash and OTP, the pre-fetch is aborted and begins again only
when a branch is made back into the flash or OTP. The flash pipeline pre-fetch mechanism only applies to
instruction fetches from program space. Data reads from data memory and from program memory do not
utilize the pre-fetch buffer capability and thus bypass the pre-fetch buffer. For example, instructions such as
MAC, DMAC, and PREAD read a data value from program memory. When this read happens, the pre-fetch
buffer is bypassed but the buffer is not flushed. If an instruction pre-fetch is already in progress when a data
read operation is initiated, then the data read will be stalled until the pre-fetch completes.
1.1.3.3 Reserved Locations Within Flash and OTP
When allocating code and data to flash and OTP memory, keep the following in mind:
1. Address locations 0x3F 7FF6 and 0x3F 7FF7 are reserved for an entry into flash branch instruction. When
the boot to flash boot option is used, the boot ROM will jump to address 0x3F 7FF6. If you program a branch
instruction here that will then re-direct code execution to the entry point of the application.
2. Addresses from 0x3F 7FF0 to 0x3F 7FF5 are reserved for data variables and should not contain program
code.
System Control and Interrupts
44
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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