7.3.4
Input Pull-Up Transistors
Port 2 has built-in programmable input pull-up transistors that are available in modes 2 and 3. The
pull-up for each bit can be turned on and off individually. To turn on an input pull-up in mode 2 or
3, set the corresponding P2PCR bit to 1 and clear the corresponding P2DDR bit to 0. P2PCR is
cleared to H'00 by a reset and in hardware standby mode, turning all input pull-ups off. In software
standby mode, the previous state is maintained.
Table 7.5 indicates the states of the input pull-up transistors in each operating mode.
Table 7.5 States of Input Pull-Up Transistors (Port 2)
Mode
Reset
Off
Hardware Standby
Software Standby
Other Operating Modes
1
2
3
Off
Off
Off
Off
Off
Off
On/off
On/off
On/off
On/off
Off
Notes: Off:
The input pull-up transistor is always off.
On/off: The input pull-up transistor is on if P2PCR = 1 and P2DDR = 0, but off otherwise.
7.4
Port 3
7.4.1
Overview
Port 3 is an 8-bit input/output port that is multiplexed with the data bus and host interface data bus.
Figure 7.9 shows the pin configuration of port 3. The pin functions differ depending on the
operating mode.
Port 3 has built-in, software-controllable MOS input pull-up transistors that can be used in mode
3.
Pins in port 3 can drive one TTL load and a 90-pF capacitive load. They can also drive a
darlington pair.
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RENESAS [ RENESAS TECHNOLOGY CORP ]
