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Chapter 16
Port Functions
Preliminary User’s Manual U15839EE1V0UM00
16.3.12 Port
CT
Port CT is a 3-bit input/output port in which input or output can be specified in 1-bit units. After reset,
port pin PCT4 operates as a read strobe signal output (RD). The port pins PCT0 and PCT1 operate as
port input after reset. Each port bit can be independently configured to port input, port output or periph-
eral function
Note 1
.
This register can be read in 1-bit and 8-bit units.
Figure 16-35:
Port CT (PCT)
Remark:
In Input Mode: When the PCT register is read, the pin levels at that time are read. Writing
to the PCT register writes the values to that register. This does not affect
the input pins.
In Output Mode:When the PCT register is read, the values of PCT are read. Writing to the
PCT register writes the values to that register and those values are
immediately output.
Besides functioning as a port, in control mode, PCT0 and PCT1 can operate as the write strobe signal
outputs when memory is accessed externally. PCT4 can also operate as the read strobe signal input.
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 PCT 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 a port pin PCT0, PCT1 or PCT4 operates as a control signal for the exter-
nal memory interface (LWR, UWR or RD), 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
PCT
0
0
0
PCT4
0
0
PCT1
PCT0
FFFFF00AH 00H
Note 2
Bit Position
Bit Name
Function
4, 1, 0
PCTn
(n = 4, 1, 0)
Input/output port
Port
Alternate Pin Name
Remarks
Block Type
Port CT
PCT4
RD
Read strobe output
D
PCT1
UWR
Upper write strobe signal output
PCT0
LWR
Lower write strobe signal output
Содержание mPD703128
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