TMS320F2811 datasheet(33/173 Pages) TI

33 / 173 page

Functional Overview

April 2001 − Revised July 2007

SPRS174O

The “Low 64K” of the memory address range maps into the data space of the 240x. The “High 64K” of the

memory address range maps into the program space of the 24x/240x. 24x/240x-compatible code will execute

only from the “High 64K” memory area. Hence, the top 32K of Flash/ROM and H0 SARAM block can be used

to run 24x/240x-compatible code (if MP/MC mode is low) or, on the 2812, code can be executed from XINTF

Zone 7 (if MP/MC mode is high).

The XINTF consists of five independent zones. One zone has its own chip select and the remaining four zones

share two chip selects. Each zone can be programmed with its own timing (wait states) and to either sample

or ignore external ready signal. This makes interfacing to external peripherals easy and glueless.

NOTE:

The chip selects of XINTF Zone 0 and Zone 1 are merged into a single chip select

(XZCS0AND1); and the chip selects of XINTF Zone 6 and Zone 7 are merged into a single chip

select (XZCS6AND7). See Section 3.5, “External Interface, XINTF (2812 only)”, for details.

Peripheral Frame 1, Peripheral Frame 2, and XINTF Zone 1 are grouped together to enable these blocks to

be “write/read peripheral block protected”. The “protected” mode ensures that all accesses to these blocks

happen as written. Because of the C28x pipeline, a write immediately followed by a read, to different memory

locations, will appear in reverse order on the memory bus of the CPU. This can cause problems in certain

peripheral applications where the user expected the write to occur first (as written). The C28x CPU supports

a block protection mode where a region of memory can be protected to make sure that operations occur as

written (the penalty is extra cycles that are added to align the operations). This mode is programmable and,

by default, it will protect the selected zones.

On the 2812, at reset, XINTF Zone 7 is accessed if the XMP/MC pin is pulled high. This signal selects

microprocessor or microcomputer mode of operation. In microprocessor mode, Zone 7 is mapped to high

memory such that the vector table is fetched externally. The Boot ROM is disabled in this mode. In

microcomputer mode, Zone 7 is disabled such that the vectors are fetched from Boot ROM. This allows the

user to either boot from on-chip memory or from off-chip memory. The state of the XMP/MC signal on reset

is stored in an MP/MC mode bit in the XINTCNF2 register. The user can change this mode in software and

hence control the mapping of Boot ROM and XINTF Zone 7. No other memory blocks are affected by

XMP/MC.

I/O space is not supported on the 2812 XINTF.

The wait states for the various spaces in the memory map area are listed in Table 3−3.

TMS320F2811 数据表(PDF) 33 Page - Texas Instruments