Datasheet

Section 9 I/O Ports
Rev. 3.00 Sep. 14, 2006 Page 134 of 408
REJ09B0105-0300
9.6 Port B
Port B is an input port also functioning as an A/D converter analog input pin and LVD external
comparison voltage input pin. Each pin of the port B is shown in figure 9.6.
PB3/AN3/ExtU
PB2/AN2/ExtD
PB1/AN1
PB0/AN0
Port B
Figure 9.6 Port B Pin Configuration
Port B has the following register.
• Port data register B (PDRB)
9.6.1 Port Data Register B (PDRB)
PDRB is a general input-only port data register of port B.
Bit Bit Name
Initial
Value R/W Description
7 to 4    Reserved
3
2
1
0
PB3
PB2
PB1
PB0




R
R
R
R
The input value of each pin is read by reading this
register.
However, if a port B pin is designated as an analog input
channel by ADCSR in A/D converter or external
comparison voltage input pin by LVDCR in low-voltage
detection circuit, 0 is read.