SLAU144K December 2004 – August 2022 MSP430AFE221 , MSP430AFE222 , MSP430AFE223 , MSP430AFE231 , MSP430AFE232 , MSP430AFE233 , MSP430AFE251 , MSP430AFE252 , MSP430AFE253 , MSP430F2001 , MSP430F2002 , MSP430F2003 , MSP430F2011 , MSP430F2012 , MSP430F2013 , MSP430F2101 , MSP430F2111 , MSP430F2112 , MSP430F2121 , MSP430F2122 , MSP430F2131 , MSP430F2132 , MSP430F2132-EP , MSP430F2232 , MSP430F2234 , MSP430F2252 , MSP430F2252-Q1 , MSP430F2254 , MSP430F2272 , MSP430F2272-Q1 , MSP430F2274 , MSP430F2274-EP , MSP430F233 , MSP430F2330 , MSP430F235 , MSP430F2350 , MSP430F2370 , MSP430F2410 , MSP430F2416 , MSP430F2417 , MSP430F2418 , MSP430F2419 , MSP430F247 , MSP430F2471 , MSP430F248 , MSP430F2481 , MSP430F249 , MSP430F2491 , MSP430F2616 , MSP430F2617 , MSP430F2618 , MSP430F2619 , MSP430G2001 , MSP430G2101 , MSP430G2102 , MSP430G2111 , MSP430G2112 , MSP430G2121 , MSP430G2131 , MSP430G2132 , MSP430G2152 , MSP430G2153 , MSP430G2201 , MSP430G2201-Q1 , MSP430G2202 , MSP430G2203 , MSP430G2210 , MSP430G2211 , MSP430G2212 , MSP430G2213 , MSP430G2221 , MSP430G2230 , MSP430G2231 , MSP430G2231-Q1 , MSP430G2232 , MSP430G2233 , MSP430G2252 , MSP430G2253 , MSP430G2302 , MSP430G2303 , MSP430G2312 , MSP430G2313 , MSP430G2332 , MSP430G2333 , MSP430G2352 , MSP430G2353 , MSP430G2402 , MSP430G2403 , MSP430G2412 , MSP430G2413 , MSP430G2432 , MSP430G2433 , MSP430G2444 , MSP430G2452 , MSP430G2453 , MSP430G2513 , MSP430G2533 , MSP430G2544 , MSP430G2553 , MSP430G2744 , MSP430G2755 , MSP430G2855 , MSP430G2955 , MSP430TCH5E
If the PC points to an address in the lower 64KB of the memory range, the calculated memory address bits 19:16 are cleared after the addition of the PC and the signed 16-bit index. This means the calculated memory address is always located in the lower 64KB and does not overflow or underflow out of the lower 64-KB memory space. The RAM and the peripheral registers can be accessed this way and existing MSP430 software is usable without modifications as shown in Figure 4-18.
Operation: | The signed 16-bit index in the next word after the instruction is added temporarily to the PC. The resulting bits 19:16 are cleared giving a truncated 16-bit memory address, which points to an operand address in the range 00000h to 0FFFFh. The operand is the content of the addressed memory location. |
Length: | Two or three words |
Comment: | Valid for source and destination. The assembler calculates the PC index and inserts it. |
Example: |
ADD.B EDE,TONI ; |
This instruction adds the 8-bit data contained in source byte EDE and destination byte TONI and places the result into the destination byte TONI. Bytes EDE and TONI and the program are located in the lower 64KB. | |
Source: | Byte EDE located at address 0579Ch, pointed to by PC + 4766h, where the PC index 4766h is the result of 0579Ch – 01036h = 04766h. Address 01036h is the location of the index for this example. |
Destination: | Byte TONI located at address 00778h, pointed to by PC + F740h, is the truncated 16-bit result of 00778h – 1038h = FF740h. Address 01038h is the location of the index for this example. |