Datasheet

dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04 AND dsPIC33FJ128MCX02/X04

3.3 DSP Engine Overview

The DSP engine 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.

The barrel shifter is capable of shifting a 40-bit value up

to 16 bits right or left, in a single cycle. The DSP

instructions operate seamlessly with all other

instructions and have been designed for optimal

real-time performance. The MAC instruction and other

associated instructions can concurrently fetch two data

operands from memory while multiplying two W

registers and accumulating and optionally saturating

the result in the same cycle. This instruction

functionality requires that the RAM data space be split

for these instructions and linear for all others. Data

space partitioning is achieved in a transparent and

flexible manner by dedicating certain working registers

to each address space.

3.4 Special MCU Features

The dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/

X04 and dsPIC33FJ128MCX02/X04 features a 17-bit

by 17-bit single-cycle multiplier that is shared by both

the MCU ALU and DSP engine. The multiplier can

perform signed, unsigned and mixed-sign

multiplication. Using a 17-bit by 17-bit multiplier for

16-bit by 16-bit multiplication not only allows you to

perform mixed-sign multiplication, it also achieves

accurate results for special operations, such as (-1.0) x

(-1.0).

The dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/

X04 and dsPIC33FJ128MCX02/X04 supports 16/16

and 32/16 divide operations, both fractional and

integer. All divide instructions are iterative operations.

They must be executed within a REPEAT loop, resulting

in a total execution time of 19 instruction cycles. The

divide operation can be interrupted during any of those

19 cycles without loss of data.

A 40-bit barrel shifter is used to perform up to a 16-bit

left or right shift in a single cycle. The barrel shifter can

be used by both MCU and DSP instructions.