Datasheet

Section 4 Exception Handling
Page 122 of 1434 R01UH0166EJ0600 Rev. 6.00
Mar 02, 2011
H8S/2633 Group, H8S/2633 F-ZTAT
TM
,
H8S/2633R F-ZTAT
TM
, H8S/2695
4.7 Notes on Use of the Stack
When accessing word data or longword data, the H8S/2633 Group assumes that the lowest address
bit is 0. The stack should always be accessed by word transfer instruction or longword transfer
instruction, 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 Rn (or MOV.W @SP+, Rn)
POP.L ERn (or MOV.L @SP+, ERn)
Setting SP to an odd value may lead to a malfunction. Figure 4.6 shows an example of what
happens when the SP value is odd.
SP
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.
SP
SP
CCR
PC
R1L
PC
H'FFFEFA
H'FFFEFB
H'FFFEFC
H'FFFEFD
H'FFFEFE
H'FFFEFF
MOV.B R1L, @–ER7
SP set to H'FFFEFF
TRAPA instruction executed
Data saved above SP Contents of CCR lost
Figure 4.6 Operation when SP Value is Odd