7 additional port features, Nxp semiconductors – NXP Semiconductors P89LPC9321 UM10310 User Manual
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UM10310
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NXP Semiconductors
UM10310
P89LPC9321 User manual
Digital outputs are disabled by putting the port pins into the input-only mode as described
in the Port Configurations section (see
).
Digital inputs on Port 0 may be disabled through the use of the PT0AD register. Bits 1
through 5 in this register correspond to pins P0.1 through P0.5 of Port 0, respectively.
Setting the corresponding bit in PT0AD disables that pin’s digital input. Port bits that have
their digital inputs disabled will be read as 0 by any instruction that accesses the port.
On any reset, PT0AD bits 1 through 5 default to logic 0s to enable the digital functions.
4.7 Additional port features
After power-up, all pins are in Input-Only mode. Please note that this is different from
the LPC76x series of devices.
•
After power-up, all I/O pins except P1.5, may be configured by software.
•
Pin P1.5 is input only. Pins P1.2 and P1.3 are configurable for either input-only or
open drain.
Every output on the P89LPC9321 has been designed to sink typical LED drive current.
However, there is a maximum total output current for all ports which must not be
exceeded. Please refer to the P89LPC9321 data sheet for detailed specifications.
All ports pins that can function as an output have slew rate controlled outputs to limit noise
generated by quickly switching output signals. The slew rate is factory-set to
approximately 10 ns rise and fall times.
Table 14.
Port output configuration
Port pin
Configuration SFR bits
PxM1.y
PxM2.y
Alternate usage
Notes
P0.0
P0M1.0
P0M2.0
KBIO, CMP2
P0.1
P0M1.1
P0M2.1
KBI1, CIN2B
Refer to
for
usage as analog inputs.
P0.2
P0M1.2
P0M2.2
KBI2, CIN2A
P0.3
P0M1.3
P0M2.3
KBI3, CIN1B
P0.4
P0M1.4
P0M2.4
KBI4, CIN1A
P0.5
P0M1.5
P0M2.5
KBI5, CMPREF
P0.6
P0M1.6
P0M2.6
KBI6, CMP1
P0.7
P0M1.7
P0M2.7
KBI7, T1
P1.0
P1M1.0
P1M2.0
TXD
P1.1
P1M1.1
P1M2.1
RXD
P1.2
P1M1.2
P1M2.2
T0, SCL
Input-only or open-drain
P1.3
P1M1.3
P1M2.3
INTO, SDA
input-only or open-drain
P1.4
P1M1.4
P1M2.4
INT1
P1.5
P1M1.5
P1M2.5
RST
P1.6
P1M1.6
P1M2.6
OCB
P1.7
P1M1.7
P1M2.7
OCC
P2.0
P2M1.0
P2M2.0
ICB
P2.1
P2M1.1
P2M2.1
OCD
P2.2
P2M1.2
P2M2.2
MOSI