124 lines
3.9 KiB
YAML
124 lines
3.9 KiB
YAML
# 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.
|