1# Copyright (c) 2020, 2021 Nordic Semiconductor ASA
2# SPDX-License-Identifier: Apache-2.0
3
4
5description: |
6    This is a representation of the nRF21540 Radio Front-End module.
7
8    See the "nordic,nrf21540-fem-spi" binding to configure the SPI
9    interface. The SPI interface should be configured as a child node
10    of the SPI bus you have connected to the FEM. Then you "connect"
11    the FEM and SPI configurations using the spi-if property.
12
13    Here is an example nRF21540 configuration with a SPI interface
14    selected, using the SPIM0 peripheral found on several nRF5 SoCs:
15
16      &spi0 {
17              compatible = "nordic,nrf-spim";
18              status = "okay";
19              cs-gpios = <&gpio1 3 GPIO_ACTIVE_LOW>;
20              /* ... MISO/MOSI/SCK pin configuration goes here ... */
21
22              my_spi_if: nrf21540-spi@0 {
23                      compatible = "nordic,nrf21540-fem-spi";
24                      reg = <0>;
25                      spi-max-frequency = <8000000>;
26              };
27      };
28
29      nrf_radio_fem: nrf21540 {
30              compatible = "nordic,nrf21540-fem";
31              tx-en-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
32              rx-en-gpios = <&gpio0 5 GPIO_ACTIVE_HIGH>;
33              spi-if = <&my_spi_if>;
34              pdn-gpios = <...>;
35              ant-sel-gpios = <...>;
36              mode-gpios = <...>;
37              /* ... other nRF21540 properties go here ... */
38      };
39
40      &radio {
41              fem = <&nrf_radio_fem>;
42      };
43
44    In the above example, the nRF21540 is configured for use with:
45
46      - TX_EN on P0.2 (from 'tx-en-gpios')
47      - RX_EN on P0.5 (from 'rx-en-gpios')
48      - SPI communication via SPIM0 (the bus, or parent node, of
49        the 'my_spi_if' node
50      - CSN on P1.3 (from index 0 in the bus node's 'cs-gpios' property)
51
52    You must perform any additional required SPI pin configuration
53    (nRF21540 MISO, MOSI, and SCK pins) within the SPI bus node
54    ('spi0' in the above example). See your SPI node's binding for
55    details on these pin mux properties. You can use any SPI node
56    available in your SoC's devicetree.
57
58    Configure any other nRF21540 pins as needed using 'pdn-gpios',
59    'ant-sel-gpios', and 'mode-gpios' properties. If unsure about the
60    format, use 'tx-en-gpios' as an example.
61
62    Finally, the nRF5 SoC's radio peripheral is set up for use with
63    the nRF21540 via the 'fem' property in the 'radio' node.
64
65compatible: "nordic,nrf21540-fem"
66
67include: base.yaml
68
69properties:
70  tx-en-gpios:
71    type: phandle-array
72    description: |
73        GPIO of the SOC controlling TX_EN pin of the nRF21540
74  rx-en-gpios:
75    type: phandle-array
76    description: |
77        GPIO of the SOC controlling RX_EN pin of the nRF21540
78  pdn-gpios:
79    type: phandle-array
80    description: |
81        GPIO of the SOC controlling PDN pin of the nRF21540
82  ant-sel-gpios:
83    type: phandle-array
84    description: |
85        GPIO of the SOC controlling ANT-SEL pin of the nRF21540
86  mode-gpios:
87    type: phandle-array
88    description: |
89        GPIO of the SOC controlling MODE pin of the nRF21540
90  spi-if:
91    type: phandle
92    description: |
93        Reference to the nordic,nrf21540-fem-spi SPI bus interface.
94
95        This must be present to support SPI control of the FEM.
96  tx-en-settle-time-us:
97    type: int
98    default: 11
99    description: |
100        Settling time in microseconds from state PG to TX.
101
102        Default value is based on Table 6 of the nRF21540 Product
103        Specification (v1.0), and can be overridden for tuned
104        configurations.
105  rx-en-settle-time-us:
106    type: int
107    default: 11
108    description: |
109        Settling time in microseconds from state PG to RX.
110
111        Default value is based on Table 6 of the nRF21540 Product
112        Specification (v1.0), and can be overridden for tuned
113        configurations.
114  pdn-settle-time-us:
115    type: int
116    default: 18
117    description: |
118        Settling time in microseconds from state PD to PG.
119
120        Default value is based on Table 6 of the nRF21540 Product
121        Specification (v1.0), and can be overridden for tuned
122        configurations.
123  trx-hold-time-us:
124    type: int
125    default: 3
126    description: |
127        Power-off time in microseconds when changing from RX or TX to PG.
128
129        Default value is based on Table 6 of the nRF21540 Product
130        Specification (v1.0), and can be overridden for tuned
131        configurations.
132  supply-voltage-mv:
133    type: int
134    description: |
135        nRF21540 supply voltage in mV.
136
137        This is used if compensation for nRF21540 supply voltage is supported
138        by software.
139