Hitachi H8/3937 Series Hardware Manual page 66

To avoid this problem, store a copy of the PDR3 data in a work area in memory. Perform the bit
manipulation on the data in the work area, then write this data to PDR3.
[A: Prior to executing BSET]
MOV. B #80 ,
MOV. B R0L ,
MOV. B R0L ,
P3
7
Input/output Input
Pin state Low
level
PCR3 0
PDR3 1
RAM0 1
[B: BSET instruction executed]
BSET #0 ,
[C: After executing BSET]
MOV. B @RAM0,
MOV. B R0L,
P3
7
Input/output Input
Pin state Low
level
PCR3 0
PDR3 1
RAM0 1
54
The PDR3 value (H'80) is written to a work area in
R0L
memory (RAM0) as well as to PDR3.
@RAM0
@PDR3
P3 P3
6 5
Input Output
High Low
level level
0 1
0 0
0 0
The BSET instruction is executed designating the PDR3
@RAM0
work area (RAM0).
The work area (RAM0) value is written to PDR3.
R0L
@PDR3
P3 P3
6 5
Input Output
High Low
level level
0 1
0 0
0 0
P3 P3 P3
4 3
Output Output Output
Low Low Low
level level level
1 1 1
0 0 0
0 0 0
P3 P3 P3
4 3
Output Output Output
Low Low Low
level level level
1 1 1
0 0 0
0 0 0
P3 P3
2 1 0
Output Output
Low Low
level level
1 1
0 0
0 0
P3 P3
2 1 0
Output Output
Low High
level level
1 1
0 1
0 1