EZ80F91MCU Datasheet, PDF (78/396 Pages) Zilog, Inc. – eZ80Acclaim-TM Flash Microcontrollers

eZ80F91 MCU
Product Specification
59
Table 6. GPIO Mode Selection
GPIO
Mode
1
2
3
4
5
6
7
8
9
Px_ALT2 Px_ALT1 Px_DDR Px_DR
Bits7:0 Bits7:0 Bits7:0 Bits7:0 Port Mode
Output
0
0
0
0 Output
0
0
0
0
1 Output
1
0
0
1
0 Input from pin
High impedance
0
0
1
1 Input from pin
High impedance
0
1
0
0 Open-drain output
0
0
1
0
1 Open-drain I/O
High impedance
0
1
1
0 Open-source I/O
High impedance
0
1
1
1 Open-source output
1
1
0
0
0 Reserved
High impedance
1
0
0
1 Interrupt—dual edge-triggered High impedance
1
0
1
0 Port B, C, or D—alternate function controls port I/O.
1
0
1
1 Port B, C, or D—alternate function controls port I/O.
1
1
0
0 Interrupt—active Low
High impedance
1
1
0
1 Interrupt—active High
High impedance
1
1
1
0 Interrupt—falling edge-triggered High impedance
1
1
1
1 Interrupt—rising edge-triggered High impedance
GPIO Mode 1. The port pin is configured as a standard digital output pin. The
value written to the Port x Data register (Px_DR) is presented on the pin.
GPIO Mode 2. The port pin is configured as a standard digital input pin. The output
is tristated (high impedance). The value stored in the Port x Data register pro-
duces no effect. As in all modes, a Read from the Port x Data register returns the
pin’s value. GPIO Mode 2 is the default operating mode following a RESET.
GPIO Mode 3. The port pin is configured as open-drain I/O. The GPIO pins do not
feature an internal pull-up to the supply voltage. To employ the GPIO pin in
OPEN-DRAIN mode, an external pull-up resistor must connect the pin to the sup-
ply voltage. Writing a 0 to the Port x Data register outputs a Low at the pin. Writing
a 1 to the Port x Data register results in high-impedance output.
GPIO Mode 4. The port pin is configured as open-source I/O. The GPIO pins do
not feature an internal pull-down to the supply ground. To employ the GPIO pin in
OPEN-SOURCE mode, an external pull-down resistor must connect the pin to the
PS019209-0504
PRELIMINARY
General-Purpose Input/Output