External flash to sleep

[boris bergman1]

My board (nrf52840 sense) has flash memory P25Q16H. When I put everything off, the board consumes 25uA. To save the last bit of current I would like to put the flash memory to deep sleep.

	spi_flash_dev = DEVICE_DT_GET(DT_ALIAS(spi_flash0));	
	if (!device_is_ready(spi_flash_dev)) {
		LOG_ERR("%s: device not ready.\n", spi_flash_dev->name);
		return ENODEV;
	}
	
	if(pm_device_action_run(spi_flash_dev, PM_DEVICE_ACTION_SUSPEND)) { //only consumes more power, 3mA ?!
		LOG_ERR("could not suspend qspi flash device %s", spi_flash_dev->name);
	}

In the debugger, eventually this function in file nrf_qspi_nor.c is executed:

#ifdef CONFIG_PM_DEVICE
static int enter_dpd(const struct device *const dev)
{
	if (IS_ENABLED(DT_INST_PROP(0, has_dpd))) {
		struct qspi_cmd cmd = {
			.op_code = SPI_NOR_CMD_DPD,
		};
		uint32_t t_enter_dpd = DT_INST_PROP_OR(0, t_enter_dpd, 0);
		int rc;

		rc = qspi_send_cmd(dev, &cmd, false);
		if (rc < 0) {
			return rc;
		}

		if (t_enter_dpd) {
			uint32_t t_enter_dpd_us =
				DIV_ROUND_UP(t_enter_dpd, NSEC_PER_USEC);

			k_busy_wait(t_enter_dpd_us);
		}
	}

	return 0;
}
#endif /* CONFIG_PM_DEVICE */

SPI_NOR_CMD_DPD is indeed to 0xB9, which is consistent with the datasheet.

Problem: after executing this command, the power rises to 3.94mA. I have no idea what is causing this.

I'm running zephyr 3.5.99 ncs 2.6.1

[morgendagen]

Hi,

I am very interested in a fix for this issue as well.

My situation is the same except I am using a non-Sense Xiao BLE: approximately 20uA if I do not do anything to power off the external flash, and 2mA if I use pm_device_action_run.

I did stumble upon a partial solution in this message: https://forum.seeedstudio.com/t/low-power-with-xiao-nrf52840-on-zephyr-rtos/270491/6. By adding flash.* from the zip-file linked to in the message  to my project and executing da_flash_init(); da_flash_command(0xB9); da_flash_uninit();, the power consumption gets down to 2.5uA, which is in line with my expectations.

So it is possible to get there, and I can use this solution in the short run since I do not need the external flash for my current project, but I would very much prefer a solution that uses Zephyr's power management module.

Best Regards,

Peder

[boris bergman1]

I read that too, I'll post his code for convenience.

flash.c

#include <nrfx_qspi.h>
#include <zephyr/drivers/gpio.h>

#define QSPI_SCK_PIN    21
#define QSPI_CS_PIN     25
#define QSPI_IO0_PIN   20
#define QSPI_IO1_PIN    24
#define QSPI_IO2_PIN    22
#define QSPI_IO3_PIN    23

int da_flash_init()
{
    const struct device * dev = DEVICE_DT_GET(DT_NODELABEL(gpio0));
    if (!device_is_ready(dev))
    {
        return -ENODEV;
    }
    gpio_pin_configure(dev, QSPI_CS_PIN, GPIO_OUTPUT_HIGH);

    nrfx_qspi_config_t qspi_cfg =
    {
        .xip_offset = 0,
        .pins =
        {
            .sck_pin = QSPI_SCK_PIN,
            .csn_pin = QSPI_CS_PIN,
            .io0_pin = QSPI_IO0_PIN,
            .io1_pin = QSPI_IO1_PIN,
            .io2_pin = QSPI_IO2_PIN,
            .io3_pin = QSPI_IO3_PIN,
        },
        .prot_if = 
        {
            .readoc = NRF_QSPI_READOC_READ4O, // 0x6B read command
            .writeoc = NRF_QSPI_WRITEOC_PP4O, // 0x32 write command
            .addrmode = NRF_QSPI_ADDRMODE_24BIT,
            .dpmconfig = false
        },
        .phy_if =
        {
            .sck_delay = 10,
            .dpmen = false,
            .spi_mode = NRF_QSPI_MODE_0,
            .sck_freq = NRF_QSPI_FREQ_32MDIV16, // start with low 2 Mhz speed
        },
        .irq_priority = 7,
        .skip_gpio_cfg = true,
        .skip_psel_cfg = false
    };

    // No callback for blocking API
    nrfx_err_t err = nrfx_qspi_init(&qspi_cfg, NULL, NULL);
    if (err != NRFX_SUCCESS)
    {
        return -err;
    }

    return 0;
} 

void da_flash_uninit()
{
    nrfx_qspi_uninit();
}

int da_flash_command(uint8_t command)
{
    nrf_qspi_cinstr_conf_t cinstr_cfg = {.opcode = command,
                                         .length = NRF_QSPI_CINSTR_LEN_1B,
                                         .io2_level = true,
                                         .io3_level = true,
                                         .wipwait = false,
                                         .wren = false};

    nrfx_err_t err = nrfx_qspi_cinstr_xfer(&cinstr_cfg, NULL, NULL);
    if (err != NRFX_SUCCESS)
    {
        return -err;
    }

    return 0;
}

main.c

da_flash_init();
da_flash_command(0xB9);
da_flash_uninit();

[Vidar Berg]

I looked at the devicetree for the XIAO BLE board and noticed that it disconnects all the QSPI pins, including CS, when the 'sleep' state is applied: https://github.com/zephyrproject-rtos/zephyr/blob/d32d4af935484b4de247a9f857dc90fb281f565e/boards/arm/xiao_ble/xiao_ble-pinctrl.dtsi#L99. This will leave the CS input on the P25Q16H floating, which I suspect may explain why it fails to enter/stay in power down mode.

Please try to apply the DT overlay included the zip below to your build and see if it helps:

3302.xiao_ble_sense.zip

[boris bergman1]

Yes thank you so much, I can confirm this works.

[morgendagen]

Hi Vidar,

I can confirm that this also works on a non-Sense board using ncs 2.7.0. Thank you so much for looking into this issue to both of you.

Best regards,

Peder