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Chapter 16
Port Functions
Preliminary User’s Manual U15839EE1V0UM00
16.3.13 Port
CM
Port CM is an 1-bit input/output port in which input or output can be specified in 1-bit units. After reset,
port pin PCM0 operates as the wait insertion input (WAIT). This port bit can be configured to port input,
port output or peripheral function
Note 1
.
This register can be read in 1-bit and 8-bit units.
Figure 16-38:
Port CM (PCM)
Remark:
In Input Mode: When the PCM register is read, the pin levels at that time are read. Writing
to the PCM register writes the values to that register. This does not affect
the input pins.
In Output Mode:When the PCM register is read, the values of PCM are read. Writing to the
PCM register writes the values to that register and those values are
immediately output.
Besides functioning as a port, in control mode, PCM0 can operate as the wait insertion signal input
when external slow memory/peripherals are connected.
Notes: 1. If using peripheral functions, the direction setting for the respective port bit is not forced
automatically. Port bit direction has to be programmed according to the peripheral function
requirement by setting the port mode register.
2. The reset value of register PCM is 00H. Due to the input mode of the port after reset, the
read input value is determined by the port pins.
(1)
Operation in control mode
Caution:
In case that the port pin PCM0 operates as a control signal for the external memory
interface (WAIT), it is recommended to plug in an external pull up resistor to that pin
7
6
5
4
3
2
1
0
Address
At Reset
PCM
0
0
0
0
0
0
0
PCM0
FFFFF00CH 00H
Note 2
Bit Position
Bit Name
Function
0
PCM0
Input/output port
Port
Alternate Pin Name
Remarks
Block Type
Port CM
PCM0
WAIT
Wait insertion signal input
E
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