Reset: A reset clears P1DDR, P1DR, and P1PCR to all “0,” placing all pins in the input state with
the pull-up transistors off. In mode 1, when the chip comes out of reset, P1DDR is set to all “1.”
Hardware Standby Mode: All pins are placed in the high-impedance state with the pull-up
transistors off. P1DR and P1PCR are initialized to H'00. In modes 2 and 3, P1DDR is initialized to
H'00.
Software Standby Mode: In the software standby mode, P1DDR, P1DR, and P1PCR remain in
their previous state. Address output pins are Low. General-purpose output pins continue to output
the data in P1DR.
Input Pull-Up Transistors: Port 1 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 P1PCR bit to “1” and clear the
corresponding P1DDR bit to “0.” P1PCR is cleared to H'00 by a reset and in the hardware standby
mode, turning all input pull-ups off. In software standby mode, the previous state is maintained.
Table 5-4 indicates the states of the input pull-up transistors in each operating mode.
Table 5-4. States of Input Pull-Up Transistors (Port 1)
Mode
Reset
Hardware standby
Software standby
Other operating modes
1
Off
Off
Off
Off
2
Off
Off
On/off
On/off
3
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 P1PCR = “1” and P1DDR = “0,” but off
otherwise.
Figure 5-1 shows a schematic diagram of port 1.
79
Summary of Contents for H8/326 Series
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