HD64F2145 Datasheet, PDF (124/829 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

4.7 Usage Note
When accessing word data or longword data, this LSI assumes that the lowest address bit is 0. The
stack should always be accessed in words or longwords, and the value of the stack pointer (SP:
ER7) should always be kept even.
Use the following instructions to save registers:
PUSH.W Rn (or MOV.W Rn, @-SP)
PUSH.L ERn (or MOV.L ERn, @-SP)
Use the following instructions to restore registers:
POP.W
POP.L
Rn (or MOV.W @SP+, Rn)
ERn (or MOV.L @SP+, ERn)
Setting SP to an odd value may lead to a malfunction. Figure 4.3 shows an example of what
happens when the SP value is odd.
Address
CCR
SP
PC
SP
R1L
H'FFEFFA
H'FFEFFB
PC
H'FFEFFC
H'FFEFFD
SP
H'FFEFFF
TRAPA instruction executed
MOV.B R1L, @-ER7 executed
SP set to H'FFFEFF
Data saved above SP
Contents of CCR lost
Legend
CCR : Condition code register
PC : Program counter
R1L : General register R1L
SP : Stack pointer
Note: This diagram illustrates an example in which the interrupt control mode is 0 in advanced mode.
Figure 4.3 Operation when SP Value is Odd
Rev. 2.0, 08/02, page 84 of 788