DSPIC30F5011 MICROCHIP [Microchip Technology], DSPIC30F5011 Datasheet - Page 13

• Manufacturer Part Number: DSPIC30F5011
• Description: High-Performance Digital Signal Controllers
• Manufacturer: MICROCHIP [Microchip Technology]

2.0
2.1
This section contains a brief overview of the CPU
architecture of the dsPIC30F. For additional hard-
ware and programming information, please refer to
the dsPIC30F
the dsPIC30F
respectively.
The core has a 24-bit instruction word. The Program
Counter (PC) is 23-bits wide with the Least Significant
(LS) bit always clear (refer to Section 3.1), and the
Most Significant (MS) bit is ignored during normal pro-
gram execution, except for certain specialized instruc-
tions. Thus, the PC can address up to 4M instruction
words of user program space. An instruction pre-fetch
mechanism is used to help maintain throughput. Pro-
gram loop constructs, free from loop count manage-
ment overhead, are supported using the DO and
REPEAT instructions, both of which are interruptible at
any point.
The working register array consists of 16 x 16-bit regis-
ters, each of which can act as data, address or offset
registers. One working register (W15) operates as a
software stack pointer for interrupts and calls.
The data space is 64 Kbytes (32K words) and is split
into two blocks, referred to as X and Y data memory.
Each block has its own independent Address Genera-
tion Unit (AGU). Most instructions operate solely
through the X memory, AGU, which provides the
appearance of a single unified data space. The
Multiply-Accumulate (MAC) class of dual source DSP
instructions operate through both the X and Y AGUs,
splitting the data address space into two parts (see
Section 3.2). The X and Y data space boundary is
device specific and cannot be altered by the user. Each
data word consists of 2 bytes, and most instructions
can address data either as words or bytes.
There are two methods of accessing data stored in
program memory:
• The upper 32 Kbytes of data space memory can
• Linear indirect access of 32K word pages within
 2004 Microchip Technology Inc.
be mapped into the lower half (user space) of pro-
gram space at any 16K program word boundary,
defined by the 8-bit Program Space Visibility Page
(PSVPAG) register. This lets any instruction
access program space as if it were data space,
with a limitation that the access requires an addi-
tional cycle. Moreover, only the lower 16 bits of
each instruction word can be accessed using this
method.
program space is also possible using any working
register, via table read and write instructions.
Table read and write instructions can be used to
access all 24 bits of an instruction word.
CPU ARCHITECTURE
OVERVIEW
Core Overview
Programmer’s
Family
Reference
Reference
Manual
Manual
and
Preliminary
Overhead-free circular buffers (modulo addressing) are
supported in both X and Y address spaces. This is
primarily intended to remove the loop overhead for
DSP algorithms.
The X AGU also supports bit-reversed addressing on
destination effective addresses to greatly simplify input
or output data reordering for radix-2 FFT algorithms.
Refer to Section 4.0 for details on modulo and
bit-reversed addressing.
The core supports Inherent (no operand), Relative,
Literal, Memory Direct, Register Direct, Register
Indirect, Register Offset and Literal Offset Addressing
modes. Instructions are associated with predefined
Addressing modes, depending upon their functional
requirements.
For most instructions, the core is capable of executing
a data (or program data) memory read, a working reg-
ister (data) read, a data memory write and a program
(instruction) memory read per instruction cycle. As a
result, 3-operand instructions are supported, allowing
C = A+B operations to be executed in a single cycle.
A DSP engine has been included to significantly
enhance the core arithmetic capability and throughput.
It features a high speed 17-bit by 17-bit multiplier, a
40-bit ALU, two 40-bit saturating accumulators and a
40-bit bidirectional barrel shifter. Data in the accumula-
tor or any working register can be shifted up to 15 bits
right, or 16 bits left in a single cycle. The DSP instruc-
tions operate seamlessly with all other instructions and
have been designed for optimal real-time performance.
The MAC class of instructions can concurrently fetch
two data operands from memory while multiplying two
W registers. To enable this concurrent fetching of data
operands, the data space has been split for these
instructions and linear for all others. This has been
achieved in a transparent and flexible manner, by ded-
icating certain working registers to each address space
for the MAC class of instructions.
The core does not support a multi-stage instruction
pipeline. However, a single stage instruction pre-fetch
mechanism is used, which accesses and partially
decodes instructions a cycle ahead of execution, in
order to maximize available execution time. Most
instructions execute in a single cycle with certain
exceptions.
The core features a vectored exception processing
structure for traps and interrupts, with 62 independent
vectors. The exceptions consist of up to 8 traps (of
which 4 are reserved) and 54 interrupts. Each interrupt
is prioritized based on a user assigned priority between
1 and 7 (1 being the lowest priority and 7 being the
highest), in conjunction with a predetermined ‘natural
order’. Traps have fixed priorities ranging from 8 to 15.
dsPIC30F5011/5013
DS70116C-page 11