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MSP430x11x1
MIXED SIGNAL MICROCONTROLLER
SLAS241C – SEPTEMBER 1999 – REVISED JUNE 2000
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
short-form description (continued)
CPU
All sixteen registers are located inside the CPU,
providing reduced instruction execution time. This
reduces a register-register operation execution
time to one cycle of the processor.
Four registers are reserved for special use as a
program counter, a stack pointer, a status register,
and a constant generator. The remaining twelve
registers are available as general-purpose
registers.
Peripherals are connected to the CPU using a
data address and control buses and can be
handled easily with all instructions for memory
manipulation.
instruction set
The instructions set for this register-register architecture provides a powerful and easy-to-use assembly
language. The instruction set consists of 51 instructions with three formats and seven addressing modes.
Table 1 provides a summation and example of the three types of instruction formats; the addressing modes are
listed in Table 2.
Table 1. Instruction Word Formats
Dual operands, source-destination e.g. ADD R4, R5 R4 + R5 → R5
Single operands, destination only e.g. CALL R8 PC → (TOS), R8 → PC
Relative jump, un-/conditional e.g. JNE Jump-on equal bit = 0
Most instructions can operate on both word and byte data. Byte operations are identified by the suffix B.
Examples: Instructions for word operation Instructions for byte operation
MOV EDE,TONI MOV.B EDE,TONI
ADD #235h,&MEM ADD.B #35h,&MEM
PUSH R5 PUSH.B R5
SWPB R5 —
Table 2. Address Mode Descriptions
ADDRESS MODE s d SYNTAX EXAMPLE OPERATION
Register √ √ MOV Rs, Rd MOV R10, R11 R10 → R11
Indexed √ √ MOV X(Rn), Y(Rm) MOV 2(R5), 6(R6) M(2 + R5) → M(6 + R6)
Symbolic (PC relative) √ √ MOV EDE, TONI M(EDE) → M(TONI)
Absolute √ √ MOV &MEM, &TCDAT M(MEM) → M(TCDAT)
Indirect √ MOV @Rn, Y(Rm) MOV @R10, Tab(R6) M(R10) → M(Tab + R6)
Indirect autoincrement √ MOV @Rn+, RM MOV @R10+, R11 M(R10) → R11, R10 + 2 → R10
Immediate √ MOV #X, TONI MOV #45, TONI #45 → M(TONI)
NOTE: s = source d = destination Rs/Rd = source register/destination register Rn = register number
Program Counter
General-Purpose Register
PC/R0
Stack Pointer
SP/R1
Status Register
SR/CG1/R2
Constant Generator
CG2/R3
R4
General-Purpose Register
R5
General-Purpose Register R14
General-Purpose Register
R15