hd66100 Renesas Electronics Corporation., hd66100 Datasheet - Page 71

• Manufacturer Part Number: hd66100
• Description: H8/3867 Series
• Manufacturer: Renesas Electronics Corporation.

Example 2: BSET instruction executed designating port 3
P3
signal at P3
example, the BSET instruction is used to change pin P3
[A: Prior to executing BSET]
Input/output Input
Pin state
PCR3
PDR3
[B: BSET instruction executed]
[C: After executing BSET]
Input/output Input
Pin state
PCR3
PDR3
[D: Explanation of how BSET operates]
When the BSET instruction is executed, first the CPU reads port 3.
Since P3
P3
value of H'80, but the value read by the CPU is H'40.
Next, the CPU sets bit 0 of the read data to 1, changing the PDR3 data to H'41. Finally, the CPU
writes this value (H'41) to PDR3, completing execution of BSET.
As a result of this operation, bit 0 in PDR3 becomes 1, and P3
However, bits 7 and 6 of PDR3 end up with different values.
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.
56
BSET
7
5
and P3
to P3
7
0
and P3
are output pins, so the CPU reads the value in PDR3. In this example PDR3 has a
6
6
#0
. The remaining pins, P3
are designated as input pins, with a low-level signal input at P3
P3
Low level High level Low level Low level Low level Low level Low level Low level
0
1
P3
Low level High level Low level Low level Low level Low level Low level High level
0
0
7
7
6
,
are input pins, the CPU reads the pin states (low-level and high-level input).
@PDR3
P3
Input
0
0
P3
Input
0
1
6
6
P3
Output
1
0
P3
Output
1
0
The BSET instruction is executed designating port 3.
5
5
5
to P3
0
, are output pins and output low-level signals. In this
P3
Output
1
0
P3
Output
1
0
4
4
0
P3
Output
1
0
P3
Output
1
0
to high-level output.
3
3
0
outputs a high-level signal.
P3
Output
1
0
P3
Output
1
0
2
2
7
and a high-level
P3
Output
1
0
P3
Output
1
0
1
1
P3
Output
1
0
P3
Output
1
1
0
0