blob: 1c89ea9f07936f3af672ae81fda8086577823a15 [file] [log] [blame]
# Copyright (c) 2021 Teslabs Engineering S.L.
# Copyright (c) 2021 Yonatan Schachter
# SPDX-License-Identifier: Apache-2.0
description: |
The RPi Pico pin controller is a node responsible for controlling
pin function selection and pin properties, such as routing a UART0 Rx
to pin 1 and enabling the pullup resistor on that 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.
*/
/* include pre-defined combinations for the SoC variant used by the board */
#include <dt-bindings/pinctrl/rpi-pico-rp2040-pinctrl.h>
&pinctrl {
/* configuration for the usart0 "default" state */
uart0_default: uart0_default {
/* group 1 */
group1 {
/* configure P0 as UART0 TX */
pinmux = <UART0_TX_P0>;
};
/* group 2 */
group2 {
/* configure P1 as UART0 RX */
pinmux = <UART0_RX_P1>;
/* enable input on pin 1 */
input-enable;
};
};
};
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.
As shown, pin configurations are organized in groups within each child node.
Each group can specify a list of pin function selections in the 'pinmux'
property.
A group can also specify shared pin properties common to all the specified
pins, such as the 'input-enable' property in group 2. Here is a list of
supported standard pin properties:
- bias-disable: Disable pull-up/down (default, not required).
- bias-pull-up: Enable pull-up resistor.
- bias-pull-down: Enable pull-down resistor.
- input-enable: Enable input from the pin.
- input-schmitt-enable: Enable input hysteresys.
- drive-strength: Set the drive strength of the pin, in milliamps. Possible
values are: 2, 4, 8, 12 (default: 4mA)
- slew-rate: If set to 0, slew rate is set to slow. If set to 1, it is set
to fast.
To link pin configurations 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-1 = <&uart0_sleep>;
pinctrl-names = "default", "sleep";
};
compatible: "raspberrypi,pico-pinctrl"
include: base.yaml
child-binding:
description: |
Definitions for a pinctrl state.
child-binding:
include:
- name: pincfg-node.yaml
property-allowlist:
- bias-disable
- bias-pull-down
- bias-pull-up
- input-enable
- input-schmitt-enable
- drive-strength
- slew-rate
properties:
pinmux:
required: true
type: array
description: |
An array of pins sharing the same group properties. Each
element of the array is an integer constructed from the
pin number and the alternative function of the pin.
drive-strength:
enum:
- 2
- 4
- 8
- 12
default: 4
description: |
The drive strength of a pin, in mA. The default value is 4mA, as this
is the power on reset value.
slew-rate:
enum:
- 0
- 1
default: 0
description: |
The slew rate of a pin. 0 corresponds to slow, and 1 corresponds to fast.
The default value is 0 (slow), as this is the power on reset value.