MSP430G2955
MSP430G2855
MSP430G2755
www.ti.com
SLAS800 –MARCH 2013
SHORT-FORM DESCRIPTION
CPU
The MSP430 CPU has a 16-bit RISC architecture
that is highly transparent to the application. All
operations, other than program-flow instructions, are
performed as register operations in conjunction with
seven addressing modes for source operand and four
addressing modes for destination operand.
Program Counter
Stack Pointer
PC/R0
SP/R1
Status Register
SR/CG1/R2
The CPU is integrated with 16 registers that provide
reduced instruction execution time. The register-to-
register operation execution time is one cycle of the
CPU clock.
Constant Generator
CG2/R3
R4
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
General-Purpose Register
R5
Four of the registers, R0 to R3, are dedicated as
program counter, stack pointer, status register, and
constant generator, respectively. The remaining
registers are general-purpose registers.
R6
R7
Peripherals are connected to the CPU using data,
address, and control buses, and can be handled with
all instructions.
R8
R9
The instruction set consists of the original 51
instructions with three formats and seven address
modes and additional instructions for the expanded
address range. Each instruction can operate on word
and byte data.
R10
R11
R12
R13
Instruction Set
The instruction set consists of 51 instructions with
three formats and seven address modes. Each
instruction can operate on word and byte data.
Table 3 shows examples of the three types of
instruction formats; Table 4 shows the address
modes.
R14
R15
Table 3. Instruction Word Formats
INSTRUCTION FORMAT
Dual operands, source-destination
Single operands, destination only
Relative jump, un/conditional
EXAMPLE
ADD R4,R5
CALL R8
JNE
OPERATION
R4 + R5 ---> R5
PC -->(TOS), R8--> PC
Jump-on-equal bit = 0
Table 4. Address Mode Descriptions(1)
ADDRESS MODE
Register
S
✓
✓
✓
✓
✓
D
✓
✓
✓
✓
SYNTAX
MOV Rs,Rd
EXAMPLE
MOV R10,R11
MOV 2(R5),6(R6)
OPERATION
R10 -- --> R11
Indexed
MOV X(Rn),Y(Rm)
MOV EDE,TONI
MOV &MEM,&TCDAT
MOV @Rn,Y(Rm)
M(2+R5) -- --> M(6+R6)
M(EDE) -- --> M(TONI)
M(MEM) -- --> M(TCDAT)
M(R10) -- --> M(Tab+R6)
Symbolic (PC relative)
Absolute
Indirect
MOV @R10,Tab(R6)
MOV @R10+,R11
MOV #45,TONI
M(R10) -- --> R11
R10 + 2-- --> R10
Indirect autoincrement
Immediate
✓
✓
MOV @Rn+,Rm
MOV #X,TONI
#45 -- --> M(TONI)
(1) S = source, D = destination
Copyright © 2013, Texas Instruments Incorporated
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