Datasheet

23.6.1 Principle of Operation
Each PORT group of up to 32 pins is controlled by the registers in PORT, as described in the figure.
These registers in PORT are duplicated for each PORT group, with increasing base addresses. The
number of PORT groups may depend on the package/number of pins.
Figure 23-3. Overview of the peripheral functions multiplexing
Port y PINCFG
Port y
Periph Signal 0
PORT bit y
PMUXEN
Data+Config
Periph Signal 1
Periph Signal 15
Port y
PMUX[3:0]
Port y PMUX Select
Port y Line Bundle
PAD y
Pad y
Peripheral Signals to
be muxed to Pad y
Port y Peripheral
Mux Enable
15
1
0
0
1
Line Bundle
PORTMUX
The I/O pins of the device are controlled by PORT peripheral registers. Each port pin has a corresponding
bit in the Data Direction (DIR) and Data Output Value (OUT) registers to enable that pin as an output and
to define the output state.
The direction of each pin in a PORT group is configured by the DIR register. If a bit in DIR is set to '1', the
corresponding pin is configured as an output pin. If a bit in DIR is set to '0', the corresponding pin is
configured as an input pin.
When the direction is set as output, the corresponding bit in the OUT register will set the level of the pin.
If bit y in OUT is written to '1', pin y is driven HIGH. If bit y in OUT is written to '0', pin y is driven LOW. Pin
configuration can be set by Pin Configuration (PINCFGy) registers, with y=00, 01, ..31 representing the
bit position.
The Data Input Value (IN) is set as the input value of a port pin with resynchronization to the PORT clock.
To reduce power consumption, these input synchronizers can be clocked only when system requires
reading the input value, as specified in the SAMPLING field of the Control register (CTRL). The value of
the pin can always be read, whether the pin is configured as input or output. If the Input Enable bit in the
Pin Configuration registers (PINCFGy.INEN) is '0', the input value will not be sampled.
In PORT, the Peripheral Multiplexer Enable bit in the PINCFGy register (PINCFGy.PMUXEN) can be
written to '1' to enable the connection between peripheral functions and individual I/O pins. The
Peripheral Multiplexing n (PMUXn) registers select the peripheral function for the corresponding pin. This
will override the connection between the PORT and that I/O pin, and connect the selected peripheral
signal to the particular I/O pin instead of the PORT line bundle.
SAM D21 Family
PORT - I/O Pin Controller
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 410