PIC24FJ128GA Datasheet, PDF (25/232 Pages) Microchip Technology – General Purpose, 16-Bit Flash Microcontrollers

PIC24FJ128GA FAMILY
REGISTER 2-2: CORCON: CORE CONTROL REGISTER
Upper Byte:
U-0
U-0
U-0
U-0
U-0
U-0
U-0
U-0
—
—
—
—
—
—
—
—
bit 15
bit 8
Lower Byte:
U-0
U-0
U-0
U-0
R/C-0
R/W-0
U-0
U-0
—
—
—
—
IPL3
PSV
—
—
bit 7
bit 0
bit 15-4
bit 3
bit 2
bit 1-0
Unimplemented: Read as ‘0’
IPL3: CPU Interrupt Priority Level Status bit
1 = CPU interrupt priority level is greater than 7
0 = CPU interrupt priority level is 7 or less
Note: User interrupts are disabled when IPL3 = 1.
PSV: Program Space Visibility in Data Space Enable bit
1 = Program space visible in data space
0 = Program space not visible in data space
Unimplemented: Read as ‘0’
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
2.3 Arithmetic Logic Unit (ALU)
The PIC24 ALU is 16 bits wide and is capable of addi-
tion, subtraction, bit shifts and logic operations. Unless
otherwise mentioned, arithmetic operations are 2’s
complement in nature. Depending on the operation, the
ALU may affect the values of the Carry (C), Zero (Z),
Negative (N), Overflow (OV) and Digit Carry (DC)
Status bits in the SR register. The C and DC Status bits
operate as Borrow and Digit Borrow bits, respectively,
for subtraction operations.
The ALU can perform 8-bit or 16-bit operations,
depending on the mode of the instruction that is used.
Data for the ALU operation can come from the W
register array, or data memory, depending on the
addressing mode of the instruction. Likewise, output
data from the ALU can be written to the W register array
or a data memory location.
The PIC24 CPU incorporates hardware support for
both multiplication and division. This includes a dedi-
cated hardware multiplier and support hardware for
16-bit divisor division.
2.3.1 MULTIPLIER
The ALU contains a high-speed 17-bit x 17-bit
multiplier. It supports unsigned, signed or mixed sign
operation in several multiplication modes:
1. 16-bit x 16-bit signed
2. 16-bit x 16-bit unsigned
3. 16-bit signed x 5-bit (literal) unsigned
4. 16-bit unsigned x 16-bit unsigned
5. 16-bit unsigned x 5-bit (literal) unsigned
6. 16-bit unsigned x 16-bit signed
7. 8-bit unsigned x 8-bit unsigned
© 2006 Microchip Technology Inc.
Preliminary
DS39747C-page 23