Deinitialize SPI

RE: Deinitialize SPI

Kenneth — Wed, 06 Dec 2023 13:05:00 GMT

Thank you for providing the additional details on how to make this work.

Kenneth

RE: Deinitialize SPI

Paul123 — Wed, 06 Dec 2023 12:35:12 GMT

Hey Kenneth,

thanks for the advice. I was able to suspend the SPI and reduce the supply current to 13uA.
pm_device_action_run(spi_dev, PM_DEVICE_ACTION_SUSPEND)did not work at first and caused a BUS FAULT ERROR and my program crashed.

It worked when I used PM_DEVICE_ACTION_SUSPEND together with the spi node instead of the spi device device everything worked fine. All I had to do after the suspension was to pull low the CS pins of my two peripherals and set them high again after resumed.

So in the end the code I use is:

CONFIG_PM_DEVICE=y in prj.conf

Deinit SPI
:const struct device *cons = DEVICE_DT_GET(DT_NODELABEL(spi1));
pm_device_action_run(cons, PM_DEVICE_ACTION_SUSPEND);
gpio_pin_set_dt(&pin_cs, 1); //CS is active high

reinit SPI:
gpio_pin_set_dt(&pin_cs, 0); //CS is active high
const struct device *cons = DEVICE_DT_GET(DT_NODELABEL(spi1));
pm_device_action_run(cons, PM_DEVICE_ACTION_RESUME);

Kind Regards Paul

RE: Deinitialize SPI

Kenneth — Fri, 01 Dec 2023 13:42:29 GMT

I was thinking along the lines of if you use CONFIG_PM_DEVICE=y, then you have the option to call for instance pm_device_action_run(spi_dev, PM_DEVICE_ACTION_SUSPEND) and pm_device_action_run(spi_dev, PM_DEVICE_ACTION_RESUME) between transfers. When spi is suspended the pins should fall back to to the sleep state you have configured in dts or overlay file. I can however see now that you are possible having an external flash, which may complicate things but not sure, since I have not looked into it.

Kenneth

RE: Deinitialize SPI

Paul123 — Fri, 01 Dec 2023 09:40:08 GMT

Thanks for the quick answer.

I didin't find the function to uninit and init the SPI. I only found the function device_is_ready(). Is there any function in zephyr to uninit the SPI?

I am using the nrf Connect SDK

in my prj.conf I set the following defines:

CONFIG_SPI=y
CONFIG_FLASH_JESD216_API=y
CONFIG_SPI_NOR=y

RE: Deinitialize SPI

Kenneth — Thu, 30 Nov 2023 14:43:12 GMT

It should not be problematic to uninit and init the the spi between transactions, e.g. by something like:

// power off sensor
// unint spi + lower cs + lower spi pins (e.g. clk, mosi)
// wait
// raise cs pin + init spi
// power on sensor

I guess how this can be done slightly depends on which sdk + driver api you are using.

Kenneth