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# Copyright (c) 2021 Nordic Semiconductor ASA
# SPDX-License-Identifier: Apache-2.0
description: |
The nRF pin controller is a singleton node responsible for controlling
pin function selection and pin properties. For example, you can use this
node to route UART0 RX to pin P0.1 and enable the pull-up resistor on the
pin.
The node has the 'pinctrl' node label set in your SoC's devicetree,
so you can modify it like this:
&pinctrl {
/* your modifications go here */
};
All device pin configurations should be placed in child nodes of the
'pinctrl' node, as shown in this example:
/* You can put this in places like a board-pinctrl.dtsi file in
* your board directory, or a devicetree overlay in your application.
*/
&pinctrl {
/* configuration for uart0 device, default state */
uart0_default: uart0_default {
/* group 1 ('group1' name is arbitrary) */
group1 {
/* configure P0.1 as UART_TX and P0.2 as UART_RTS */
psels = <NRF_PSEL(UART_TX, 0, 1)>, <NRF_PSEL(UART_RTS, 0, 2)>;
};
/* group 2 */
group2 {
/* configure P0.3 as UART_RX and P0.4 as UART_CTS */
psels = <NRF_PSEL(UART_RX, 0, 3)>, <NRF_PSEL(UART_CTS, 0, 4)>;
/* both P0.3 and P0.4 are configured with pull-up */
bias-pull-up;
};
};
};
The 'uart0_default' child node encodes the pin configurations for a
particular state of a device; in this case, the default (that is, active)
state. You would specify the low-power configuration for the same device
in a separate child node.
As shown, pin configurations are organized in groups within each child node.
Each group can specify a list of pin function selections in the 'psels'
property. The NRF_PSEL macro is used to specify a pin function selection.
If a pin needs to be explicitly disconnected, there is also the
NRF_PSEL_DISCONNECTED macro.
Available pin functions can be found in the
include/zephyr/dt-bindings/pinctrl/nrf-pinctrl.h header file.
A group can also specify shared pin properties common to all the specified
pins, such as the 'bias-pull-up' property in group 2. Here is a list of
supported standard pin properties:
- bias-disable: Disable pull-up/down (default behavior, not required).
- bias-pull-up: Enable pull-up resistor.
- bias-pull-down: Enable pull-down resistor.
- low-power-enable: Configure pin as an input with input buffer
disconnected.
Note that bias options are mutually exclusive.
To link this pin configuration with a device, use a pinctrl-N property
for some number N, like this example you could place in your board's DTS
file:
#include "board-pinctrl.dtsi"
&uart0 {
pinctrl-0 = <&uart0_default>;
pinctrl-names = "default";
};
compatible: "nordic,nrf-pinctrl"
include: base.yaml
child-binding:
description: |
nRF pin controller pin configuration state nodes.
child-binding:
description: |
nRF pin controller pin configuration group.
include:
- name: pincfg-node.yaml
property-allowlist:
- bias-disable
- bias-pull-down
- bias-pull-up
- low-power-enable
properties:
psels:
required: true
type: array
description: |
An array of pins sharing the same group properties. The pins should
be defined using the NRF_PSEL utility macro that encodes the port,
pin and function. NRF_PSEL_DISCONNECTED is also available to explicitly
disconnect a pin.
nordic,drive-mode:
type: int
default: 0
description: |
Pin output drive mode. Available drive modes are pre-defined in
nrf-pinctrl.h. Note that extra modes may not be available on certain
devices. Defaults to standard mode for 0 and 1 (NRF_DRIVE_S0S1), the
SoC default, except for the "nordic,nrf-twi" and "nordic,nrf-twim"
nodes where NRF_DRIVE_S0S1 is always overridden with NRF_DRIVE_S0D1
(standard '0', disconnect '1').
nordic,invert:
type: boolean
description: |
Invert pin polarity (set the active state to low).
Only valid for PWM channel output pins.