HD6412240 RENESAS [Renesas Technology Corp], HD6412240 Datasheet - Page 111

• Manufacturer Part Number: HD6412240
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2200 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Example: To clear only bit 4 in the port 1 P1DDR
The P1DDR register consists of 8 write-only bits and sets the I/O direction of the port 1 pins.
Reading this register is invalid. When read, the values returned are undefined.
Here we present an example in which P14 is specified to be an input port using the BCLR
instruction. First, we write the initial value H'F0 written to P1DDR to the work area in RAM
(RAM0).
MOV.B
MOV.B
MOV.B
I/O
P1DDR
RAM0
Figure 2.21 Flowchart for Access Methods for Registers That Include Write-Only Bits
#H'F0,
R0L,
R0L,
Write the work area data to the register
register that includes write-only bits
(data transfer and bit manipulation
Output
Write the work area data to the
P17
Write data to the work area
that includes write-only bits
Access the work area data
instructions can be used)
1
1
R0L
@PAM0
@P1DDR
Output
P16
1
1
Output
P15
1
1
Output
P14
1
1
Rev.3.00 Mar. 26, 2007 Page 69 of 772
Input
P13
Initial value write
Modifying the value of a register
that includes write-only bits
0
0
Input
P12
0
0
REJ09B0355-0300
Input
P11
Section 2 CPU
0
0
Input
P10
0
0