575
Chapter 16
Port Functions
Preliminary User’s Manual U15839EE1V0UM00
16.3.10 Port
AH
Port AH is an 8-bit input/output port in which input or output can be specified in 1-bit units. After reset,
the port AH pins operate as an address bus to address external memories respectively peripherals.
Each port bit can be independently configured to port input, port output or peripheral function
Note 1
.
This register can be read in 1-bit and 8-bit units.
Figure 16-29:
Port AH (PAH)
Remark:
In Input Mode: When the PAH register is read, the pin levels at that time are read. Writing
to the PAH register writes the values to that register. This does not affect
the input pins.
In Output Mode:When the PAH register is read, the values of PAH are read. Writing to the
PAH register writes the values to that register and those values are
immediately output.
Besides functioning as a port, in control mode, it also can operate as an address bus.
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 PAH 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
7
6
5
4
3
2
1
0
Address
At Reset
PAH
PAH7
PAH6
PAH5
PAH4
PAH3
PAH2
PAH1
PAH0
FFFFF002H 00H
Note 2
Bit Position
Bit Name
Function
7 to 0
PAHn
(n = 7 to 0)
Input/output port
Port
Alternate Pin Name
Remarks
Block Type
Port AH
PAH7 to
PAH0
A23 to A16
Address bus
B
Summary of Contents for mPD703128
Page 6: ...6 Preliminary User s Manual U15839EE1V0UM00 ...
Page 20: ...20 Preliminary User s Manual U15839EE1V0UM00 ...
Page 32: ...32 Preliminary User s Manual U15839EE1V0UM00 MEMO ...
Page 154: ...154 Preliminary User s Manual U15839EE1V0UM00 MEMO ...
Page 238: ...238 Preliminary User s Manual U15839EE1V0UM00 MEMO ...
Page 356: ...356 Preliminary User s Manual U15839EE1V0UM00 MEMO ...
Page 522: ...522 Preliminary User s Manual U15839EE1V0UM00 MEMO ...
Page 600: ...600 Preliminary User s Manual U15839EE1V0UM00 MEMO ...
Page 610: ...610 Preliminary User s Manual U15839EE1V0UM00 ...
Page 612: ......