Spi device tree source code

2022-08-11 Thursday

Notes on SPI device tree source, with goal to add SPI device to modified RPi Pico DTS files, which build firmware to run on Sparkfun DEV-18288 board.

In Zephyr RTOS' supported board dts files we find SPI peripherals defined for several boards. Here are excerpts

zephyr/boards/arm/sparkfun_thing_plus_nrf9160/sparkfun_thing_plus_nrf9160_common.dts {- |- |

1

|

&spi3 {
        compatible = "nordic,nrf-spim";
        status = "okay";
        cs-gpios = <&gpio0 7 GPIO_ACTIVE_LOW>;
        pinctrl-0 = <&spi3_default>;
        pinctrl-1 = <&spi3_sleep>;
        pinctrl-names = "default", "sleep";
        w25q32jv: w25q32jv@0 {
                compatible = "jedec,spi-nor";
                label = "W25Q32JV";
                reg = <0>;
                spi-max-frequency = <40000000>;
                wp-gpios = <&gpio0 8 GPIO_ACTIVE_LOW>;
                hold-gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;
                size = <0x2000000>;
                has-dpd;
                t-enter-dpd = <3000>;
                t-exit-dpd = <30000>;
                jedec-id = [ ef 40 16 ];
        };
};

|

|

|}

^ YAML device bindings files

To support a typical development kit or custom board with multiple peripherals we need a device bindings file comparable to this ... bindings file:

1. ~/projects-sandbox/workspace-for-rpi/zephyr/boards/arm/nrf9160dk_nrf9160/nrf9160dk_nrf9160.yaml

identifier: nrf9160dk_nrf9160
name: nRF9160-DK-NRF9160
type: mcu 
arch: arm 
toolchain:
  - gnuarmemb
  - xtools
  - zephyr
ram: 88
flash: 256 
supported:
  - arduino_gpio
  - arduino_i2c
  - gpio
  - i2c
  - pwm
  - spi
  - watchdog
  - counter