CPU Registers
4-26
16-Bit MSP430X CPU
MSP430 Instruction with Symbolic Mode in Upper Memory
If the PC points to an address above the lower 64-KB memory, the PC bits
19:16 are used for the address calculation of the operand. The operand may
be located in memory in the range PC
±
32 KB, because the index, X, is a
signed 16-bit value. In this case, the address of the operand can overflow or
underflow into the lower 64-KB memory space as shown in Figure 4−20 and
Figure 4−21.
Figure 4−20. Symbolic Mode Running in Upper Memory
16-bit signed PC
index (sign
extended to
20 bits)
Program
counter PC
20-bit signed add
Memory address
FFFFF
00000
Lower 64 KB
0FFFF
10000
PC.19:0
Upper Memory
PC.19:16 > 0
16-bit byte index
1 ... 15
19
16 15
0
S
PC
±
32 KB
S
Figure 4−21. Overflow and Underflow for the Symbolic Mode
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
FFFFF
0000C
Lower
64 KB
0FFFF
10000
PC.19:0
PC.19:0
PC.19:0
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
±
32KB
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
ÇÇÇÇÇÇ
±
32KB
PC.19:0
Summary of Contents for MSP430x4xx Family
Page 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Page 2: ......
Page 6: ...vi ...
Page 114: ...3 76 RISC 16 Bit CPU ...
Page 304: ...5 20 FLL Clock Module ...
Page 340: ...7 8 Supply Voltage Supervisor ...
Page 348: ...8 8 16 Bit Hardware Multiplier ...
Page 372: ...9 24 32 Bit Hardware Multiplier ...
Page 400: ...10 28 DMA Controller ...
Page 428: ...13 10 Basic Timer1 ...
Page 466: ...15 24 Timer_A ...
Page 522: ...17 30 USART Peripheral Interface UART Mode ...
Page 544: ...18 22 USART Peripheral Interface SPI Mode ...
Page 672: ...23 12 Comparator_A ...
Page 692: ...24 20 LCD Controller ...
Page 746: ...26 28 ADC12 ...