7.4.4
Input Pull-Up Transistors
Port 3 has built-in programmable input pull-up transistors that are available in mode 3. The pull-up
for each bit can be turned on and off individually. To turn on an input pull-up in mode 3, set the
corresponding P3PCR bit to 1 and clear the corresponding P3DDR bit to 0. P3PCR 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 7.7 indicates the states of the input pull-up transistors in each operating mode.
Table 7.7 States of Input Pull-Up Transistors (Port 3)
Mode
Reset
Off
Hardware Standby
Software Standby
Other Operating Modes
1
2
3
Off
Off
Off
Off
Off
Off
Off
Off
Off
On/off
On/off
Notes: Off:
The input pull-up transistor is always off.
On/off: The input pull-up transistor is on if P3PCR = 1 and P3DDR = 0, but off otherwise.
7.5
Port 4
7.5.1
Overview
Port 4 is an 8-bit input/output port that is multiplexed with input/output pins (TMRI0, TMRI1,
TMCI0, TMCI1, TMO0, TMO1) of 8-bit timers 0 and 1 and output pins (PW0, PW1) of PWM timers
0 and 1. In slave mode, P43 to P45 output host interrupt requests. Pins not used by timers or for
host interrupt requests are available for general input/output.
Figure 7.12 shows the pin configuration of port 4.
Pins in port 4 can drive one TTL load and a 90-pF capacitive load. They can also drive a
darlington pair.
129
RENESAS [ RENESAS TECHNOLOGY CORP ]
