1.3.1 Emulation Logic
1.3.2 Memory Map
1.3.3 On-Chip Program and Data
1.3.4 CPU Interrupt Vectors
1.4
Memory Interface
Memory Interface
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The emulation logic is identical to that on the C28x fixed-point CPU. This logic includes the following
features. For more details about these features, refer to the
TMS320C28x DSP CPU and Instruction Set
Reference Guide
(literature number
•
Debug-and-test direct memory access (DT-DMA). A debug host can gain direct access to the content
of registers and memory by taking control of the memory interface during unused cycles of the
instruction pipeline.
•
A counter for performance benchmarking.
•
Multiple debug events. Any of the following debug events can cause a break in program execution:
– A breakpoint initiated by the ESTOP0 or ESTOP1 instruction.
– An access to a specified program-space or data-space location.
When a debug event causes the C28x to enter the debug-halt state, the event is called a break event.
•
Real-time mode of operation.
Like the C28x, the C28x+FPU uses 32-bit data addresses and 22-bit program addresses. This allows for a
total address reach of 4G words (1 word = 16 bits) in data space and 4M words in program space.
Memory blocks on all C28x+FPU designs are uniformly mapped to both program and data space. For
specific details about each of the map segments, see the data sheet for your device.
All C28x+FPU based devices contain at least two blocks of single access on-chip memory referred to as
M0 and M1. Each of these blocks is 1K words in size. M0 is mapped at addresses 0x0000 – 0x03FF and
M1 is mapped at addresses 0x0400 – 0x07FF. Like all other memory blocks on the C28x+FPU devices,
M0 and M1 are mapped to both program and data space. Therefore, you can use M0 and M1 to execute
code or for data variables. At reset, the stack pointer is set to the top of block M1. Depending on the
device, it may also have additional random-access memory (RAM), read-only memory (ROM), external
interface zones, or flash memory.
The C28x+FPU interrupt vectors are identical to those on the C28x CPU. Sixty-four addresses in program
space are set aside for a table of 32 CPU interrupt vectors. The CPU vectors can be mapped to the top or
bottom of program space by way of the VMAP bit. For more information about the CPU vectors, see
TMS320C28x DSP CPU and Instruction Set Reference Guide
(literature number
). For devices
with a peripheral interrupt expansion (PIE) block, the interrupt vectors will reside in the PIE vector table
and this memory can be used as program memory.
The C28x+FPU memory interface is identical to that on the C28x. The C28x+FPU memory map is
accessible outside the CPU by the memory interface, which connects the CPU logic to memories,
peripherals, or other interfaces. The memory interface includes separate buses for program space and
data space. This means an instruction can be fetched from program memory while data memory is being
accessed. The interface also includes signals that indicate the type of read or write being requested by the
CPU. These signals can select a specified memory block or peripheral for a given bus transaction. In
addition to 16-bit and 32-bit accesses, the C28x+FPU supports special byte-access instructions that can
access the least significant byte (LSByte) or most significant byte (MSByte) of an addressed word. Strobe
signals indicate when such an access is occurring on a data bus.
10
Introduction
SPRUEO2A – June 2007 – Revised August 2008
Summary of Contents for TMS320C28 series
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