HD6432160 RENESAS [Renesas Technology Corp], HD6432160 Datasheet - Page 101

• Manufacturer Part Number: HD6432160
• Description: Hitachi 16-Bit Single-Chip Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

Prior to executing BCLR:
BCLR instruction executed:
After executing BCLR:
Operation:
1. When the BCLR instruction is executed, first the CPU reads P4DDR.
2. The CPU clears bit 0 of the read data to 0, changing data to H'FE.
3. The CPU writes H'FE to DDR, completing execution of BCLR.
As a result of the BCLR instruction, bit 0 in DDR is set to 0, and P40 becomes an input pin.
However, bits 7 and 6 of DDR are modified to 1, therefore P47 and P46 become output pins.
Input/output
Pin state
DDR
DR
BCLR #0,
Input/output
Pin state
DDR
DR
Since P4DDR is a write-only register, so the CPU reads H’FF. In this example P4DDR has a
value of H'3F, but the value read by the CPU is H'FF.
@P4DDR
P47
Input
Low
level
0
1
P47
Output
Low
level
1
1
Output
P46
Input
High
level
0
0
P46
High
level
1
0
The BCLR instruction is executed for DDR in port 4.
Output
P45
Output
Low
level
1
0
P45
Low
level
1
0
Output
P44
Output
Low
level
1
0
P44
Low
level
1
0
Output
P43
Output
Low
level
1
0
P43
Low
level
1
0
Rev. 2.0, 08/02, page 61 of 788
Output
P42
Output
Low
level
1
0
P42
Low
level
1
0
P41
P41
Output
Output
Low
level
1
0
Low
level
1
0
P40
P40
Input
Output
Low
level
1
0
High
level
0
0