Panasonic MN101C00 User Manual page 60

Chapter 3 Port Functions
Setting the PAIMD register
prevents unnecessary current
from flowing in a pin when an
intermediate voltage (analog
voltage) is applied to the pin.
FLOAT1
46
Port Control Registers
Port Output/Input Mode Registers
• PnOMD/PnIMD registers
These register settings determine whether the port pins(P10 to P14, PA0 to PA5) are used
as I/O ports or as special function pins (dual function).
If the special (dual) functions used, the PnDIR, PnPLU, PnPLUD, and other registers
must be set.
I/O port
0
Special function pin
1
Pin Control Registers
• FLOAT1 registers
This register specifies whether the resistors-attached to pins P7 and PA are pull-up
resistors or pull-down resistors.
In addition, this register selects either zero cross input or Schmitt trigger input for pin
P21.
7 6 5 4
Figure 3-2-2 Pin Control Register 1(FLOAT1: X'03F4B',R/W)
3 2 1 0
P21IM PARDWN P7RDWN
(at reset: -----000)
P7 pull-up/pull-down
P7RDWN
resistor selection
0 pull-up resistor
1 pull-down resistor
PA pull-up/pull-down
PARDWN
resistor selection
0 pull-up resistor
1 pull-down resistor
P21IM P21 input mode selection
0 Schmitt trigger input
1 SENS input