Low power mode in Zephyr

Question

Hello,

I'm using zephyr to develop a battery powered IoT device with a sensor and a LoRa transceiver (SX126x). And I'm expecting to achieve average consumption values (during "sleep" mode) around ~15uA. At this moment I can only get ~360uA. I've already found many other users with the same issue in this forum and already know that I need to deactivate the SoC's peripherals that I'm not using. The issue is that I can't find which peripherals are these, already tried to deactivate some but the results were not the expected. To ease my debug processes, I developed a small code with a similar behavior as the one to be used in the final product, which I will share here:

#include <zephyr.h>
#include <sys/printk.h>
#include <power/power.h>
#include <device.h>
#include <drivers/i2c.h>
#include <drivers/spi.h>
#include <drivers/lora.h>
#include <drivers/counter.h>
#include <radio.h>

#define I2C_DEV DT_INST(0, nordic_nrf_twi)

#define DEFAULT_RADIO_NODE DT_ALIAS(lora0)
BUILD_ASSERT(DT_NODE_HAS_STATUS(DEFAULT_RADIO_NODE, okay),
	     "No default LoRa radio specified in DT");
#define DEFAULT_RADIO DT_LABEL(DEFAULT_RADIO_NODE)

#if defined(CONFIG_COUNTER_RTC0)
#define TIMER DT_LABEL(DT_NODELABEL(rtc0))
#elif defined(CONFIG_COUNTER_RTC1)
#define TIMER DT_LABEL(DT_NODELABEL(rtc1))
#elif defined(CONFIG_COUNTER_RTC2)
#define TIMER DT_LABEL(DT_NODELABEL(rtc2))
#endif

#define CONSOLE_LABEL DT_LABEL(DT_CHOSEN(zephyr_console))

#define MAX_DATA_LEN 10

void t1_f();
void alarm_cback(struct device *counter_dev, uint8_t chan_id, uint32_t ticks, void *user_data);
void wakeup();
void sleep();

struct device *i2c_dev, *lora_dev, *counter, *cons;
struct counter_alarm_cfg alarm;
struct lora_modem_config lora;
char data[MAX_DATA_LEN] = {'h', 'e', 'l', 'l', 'o', 'w', 'o', 'r', 'l', 'd'};

K_THREAD_DEFINE(t1, 1024, t1_f, NULL, NULL, NULL, -1, 0, 0);

void main(void)
{
    cons = device_get_binding(CONSOLE_LABEL);
    printk("Initializing test...\n");
	i2c_dev = device_get_binding(DT_LABEL(I2C_DEV));
	if (!i2c_dev) {
		printk("I2C: Device driver not found.\n");
		return;
	}
	lora_dev = device_get_binding(DEFAULT_RADIO);
	if (!lora_dev) {
		printk("LORA: Device driver not found.\n");
		return;
	}
	lora.frequency = 868100000;
	lora.bandwidth = BW_125_KHZ;
	lora.datarate = SF_10;
	lora.preamble_len = 8;
	lora.coding_rate = CR_4_5;
	lora.tx_power = 4;
	lora.tx = true;
	lora_config(lora_dev, &lora);
    counter = device_get_binding(TIMER);
    if (!counter) {
		printk("COUNTER: Device driver not found.\n");
		return;        
    }
    counter_start(counter);
    alarm.flags = 0;
    alarm.ticks = counter_us_to_ticks(counter, 10000000);
    alarm.callback = alarm_cback;
    counter_set_channel_alarm(counter, 0, &alarm);
    sleep();
}

void t1_f(void){
	int ret;    
    uint8_t buffer[2];
    while (true)
    {
        k_sleep(K_FOREVER);
        wakeup();
        printk("t1\n");
        i2c_reg_read_byte(i2c_dev, 0x41, 0xFF, &buffer[0]); //0x07
        i2c_reg_read_byte(i2c_dev, 0x41, 0xFE, &buffer[1]); //0xD0
        printk("DEVID: %02x%02x\n", buffer[0], buffer[1]);
        ret = lora_send(lora_dev, data, MAX_DATA_LEN);
		if (ret < 0) {
			printk("LoRa send failed\n");
			return;
		}
		printk("Data sent!\n");
        k_busy_wait(3000000);
        sleep();
    }
}

void alarm_cback(struct device *counter_dev, uint8_t chan_id, uint32_t ticks, void *user_data){
    k_wakeup(t1);
    counter_set_channel_alarm(counter, 0, &alarm);
}

void wakeup(){
    device_set_power_state(cons, DEVICE_PM_ACTIVE_STATE, NULL, NULL);
    device_set_power_state(i2c_dev, DEVICE_PM_ACTIVE_STATE, NULL, NULL);
    device_set_power_state(lora_dev, DEVICE_PM_ACTIVE_STATE, NULL, NULL);
}

void sleep(){
    device_set_power_state(cons, DEVICE_PM_OFF_STATE, NULL, NULL);
    device_set_power_state(i2c_dev, DEVICE_PM_OFF_STATE, NULL, NULL);
    device_set_power_state(lora_dev, DEVICE_PM_OFF_STATE, NULL, NULL);
}

CONFIG_CONSOLE=y
CONFIG_I2C=y
CONFIG_SPI=y
CONFIG_GPIO=y
CONFIG_PRINTK=y

CONFIG_COUNTER=y
CONFIG_COUNTER_RTC0=y

CONFIG_LORA=y
CONFIG_LORA_SX12XX=y
CONFIG_LORA_SX126X=y

CONFIG_SYS_POWER_MANAGEMENT=y
CONFIG_TICKLESS_IDLE=y
CONFIG_DEVICE_POWER_MANAGEMENT=y

I could summarize my questions in:

Is there a better form of managing the devices in Zephyr?
Is there a way to know which devices are being used, and in which mode are they?
Or if I'm thinking right, but doing something wrong in the code?

Kind regards,

Diogo Correia

PS: these values were measured using the power profile kit in external mode due to the presence of a shield in the development board.