C2510Fx / CC2511Fx
13.4 I/O Ports
of a port pin, at any time, the registers PxDIR
are used to set each port pin to be either an
input or an output. Thus by setting the
Note: P0_6 and P0_7 do not exist on CC2511Fx.
The CC2511Fx has 19 digital input/output pins
available and the ADC inputs A6 and A7 can
not be used. Apart from this, all information in
this section applies to both CC2511Fx and
CC2510Fx. For all registers in this section, an x
in the register name can be replaced by 0, 1,
or, 2, referring to the port number, if nothing
else is stated.
appropriate bit within PxDIR
to 1, the
corresponding pin becomes an output.
When reading the port registers P0, P1, and
P2, the logic values on the input pins are
returned regardless of the pin configuration.
This does not apply during the execution of
read-modify-write instructions. The read-
modify-write instructions are: ANL, ORL, XRL,
JBC, CPL, INC, DEC, DJNZ, and MOV, CLR,
or SETB. Operating on a port registers the
following is true: When the destination is an
individual bit in a port register P0, P1or P2the
value of the register, not the value on the pin,
is read, modified, and written back to the port
register.
The CC2510Fx has 21 digital input/output pins
that can be configured as general purpose
digital I/O or as peripheral I/O signals
connected to the ADC, Timers, I2S, or USART
peripherals. The usage of the I/O ports is fully
configurable from user software through a set
of configuration registers.
The I/O ports have the following key features:
• 21 digital input/output pins
When used as an input, the general purpose
I/O port pins can be configured to have a pull-
up, pull-down, or tri-state mode of operation.
By default, inputs are configured as inputs with
pull-up. To de-select the pull-up/pull-down
function on an input the appropriate bit within
the PxINPmust be set to 1. The I/O port pins
P1_0 and P1_1 do not have pull-up/pull-down
capability.
• General purpose I/O or peripheral I/O
• Pull-up or pull-down capability on inputs,
except on P1_0 and P1_1.
• External interrupt capability
The external interrupt capability is available on
all 21 I/O pins. Thus, external devices may
generate interrupts if required. The external
interrupt feature can also be used to wake up
from all four power modes (PM{0-3}).
In PM1, PM2, and PM3 the I/O pins retain the
I/O mode and output value (if applicable) that
was set when PM1/2/3 was entered.
13.4.1 General Purpose I/O
13.4.2 Unused I/O Pins
When used as general purpose I/O, the pins
are organized as three 8-bit ports, port 0, 1,
and 2, denoted P0, P1, and P2. P0 and P1 are
complete 8-bit wide ports while P2 has only
five usable bits (P2_0 to P2_4). All ports are
both bit- and byte addressable through the
SFRs P0, P1 and P2. Each port pin can
individually be set to operate as a general
purpose I/O or as a peripheral I/O.
Unused I/O pins should have a defined level
and not be left floating. One way to do this is
to leave the pin unconnected and configure
the pin as a general purpose I/O input with
pull-up resistor. This is the default state of all
pins after reset except for P1_0 and P1_1
which do not have pull-up/pull-down resistors
(note that only P2_2 has pull-up during reset).
Alternatively the pin can be configured as a
general purpose I/O output. In both cases the
pin should not be connected directly to VDD or
GND in order to avoid excessive power
consumption.
Note: P1_0 and P1_1 have LED driving
capabilities.
To use a port as a general purpose I/O pin the
pin must first be configured. The registers
PxSELare used to configure each pin in a port
either as a general purpose I/O pin or as a
peripheral I/O signal. All digital input/output
pins are configured as general-purpose I/O
pins by default.
13.4.3 Low I/O Supply Voltage
In applications where the digital I/O power
supply voltage pin DVDD is below 2.6 V, the
register bit PICTL.PADSC should be set to 1
in order to obtain output DC characteristics
specified in Section 7.16.
By default, all general-purpose I/O pins are
configured as inputs. To change the direction
SWRS055D
Page 88 of 243
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