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5-3
I/O PORTS
EP_PIN
Address:
Reset State:
1FE7H
XXH
Each bit of the extended port input (EP_PIN) register reflects the current state of the corresponding
pin, regardless of the pin configuration.
7 0
PIN7 PIN6 PIN5 PIN4 PIN3 PIN2 PIN1 PIN0
Bit
Number
Bit
Mnemonic
Function
7:0 PIN7:0 Extended Address Port Pin
x
Input
This bit contains the current state of EPORT.
x
.
Figure 5-4. Extended Port Input (EP_PIN) Register
EP_REG
Address:
Reset State:
1FE5H
00H
Each bit of the extended port data output (EP_REG) register contains data to be driven out by the
corresponding pin. When a pin is configured as standard I/O (EP_MODE.
x
= 0), the result of a CPU
write to EP_REG is immediately visible on the pin.
During nonextended data accesses, EP_REG contains the value of the memory page that is to be
accessed. For compatibility with software tools, clear the EP_REG bit for any EPORT pin that is
configured as an extended-address signal (EP_MODE.
x
set).
7 0
PIN7 PIN6 PIN5 PIN4 PIN3 PIN2 PIN1 PIN0
Bit
Number
Bit
Mnemonic
Function
7:0 PIN7:0 Extended Address Port Pin
x
Output
If EPORT.
x
is to be used as an output, write the data that it is to drive
out.
If EPORT.
x
is to be used as an input, set this bit.
If EPORT.
x
is to be used as an address line, write the correct value for
the memory page to be accessed by nonextended instructions.
Figure 5-5. Extended Port Data Output (EP_REG) Register