Datasheet
dsPIC33EPXXXGP50X, dsPIC33EPXXXMC20X/50X AND PIC24EPXXXGP/MC20X
DS70657G-page 386 2011-2013 Microchip Technology Inc.
Most instructions are a single word. Certain double-word
instructions are designed to provide all the required
information in these 48 bits. In the second word, the
8MSbs are ‘0’s. If this second word is executed as an
instruction (by itself), it executes as a NOP.
The double-word instructions execute in two instruction
cycles.
Most single-word instructions are executed in a single
instruction cycle, unless a conditional test is true, or the
Program Counter is changed as a result of the instruction,
or a PSV or table read is performed, or an SFR register is
read. In these cases, the execution takes multiple
instruction cycles with the additional instruction cycle(s)
executed as a NOP. Certain instructions that involve
skipping over the subsequent instruction require either
two or three cycles if the skip is performed, depending on
whether the instruction being skipped is a single-word or
two-word instruction. Moreover, double-word moves
require two cycles.
Note: For more details on the instruction set,
refer to the “16-bit MCU and DSC
Programmer’s Reference Manual”
(DS70157).
For more information on instructions that
take more than one instruction cycle to
execute, refer to Section 2. “CPU” of
the “dsPIC33E/PIC24E Family Refer-
ence Manual” (DS70359), particularly
Section 2.8, “Instruction Flow Types”.
TABLE 28-1: SYMBOLS USED IN OPCODE DESCRIPTIONS
Field Description
#text Means literal defined by “text”
(text) Means “content of text”
[text] Means “the location addressed by text”
{ } Optional field or operation
a {b, c, d} a is selected from the set of values b, c, d
<n:m> Register bit field
.b Byte mode selection
.d Double-Word mode selection
.S Shadow register select
.w Word mode selection (default)
Acc One of two accumulators {A, B}
AWB Accumulator write back destination address register {W13, [W13]+ = 2}
bit4 4-bit bit selection field (used in word addressed instructions) {0...15}
C, DC, N, OV, Z MCU Status bits: Carry, Digit Carry, Negative, Overflow, Sticky Zero
Expr Absolute address, label or expression (resolved by the linker)
f File register address {0x0000...0x1FFF}
lit1 1-bit unsigned literal {0,1}
lit4 4-bit unsigned literal {0...15}
lit5 5-bit unsigned literal {0...31}
lit8 8-bit unsigned literal {0...255}
lit10 10-bit unsigned literal {0...255} for Byte mode, {0:1023} for Word mode
lit14 14-bit unsigned literal {0...16384}
lit16 16-bit unsigned literal {0...65535}
lit23 23-bit unsigned literal {0...8388608}; LSb must be ‘0’
None Field does not require an entry, can be blank
OA, OB, SA, SB DSP Status bits: ACCA Overflow, ACCB Overflow, ACCA Saturate, ACCB Saturate
PC Program Counter
Slit10 10-bit signed literal {-512...511}
Slit16 16-bit signed literal {-32768...32767}
Slit6 6-bit signed literal {-16...16}
Wb Base W register {W0...W15}
Wd Destination W register { Wd, [Wd], [Wd++], [Wd--], [++Wd], [--Wd] }
Wdo Destination W register
{ Wnd, [Wnd], [Wnd++], [Wnd--], [++Wnd], [--Wnd], [Wnd+Wb] }