Hello, I am working with a Seeed XIAO nRF52840.
I'm able to get an average of 500 uA in SYSTEM OFF mode. However, for this application, the current consumption during wake-up is quite high (6mA plateau and then an 8 mA peak).
I would like to know if there is a way to reduce this consumption, right now I'm doing the programming in Arduino IDE using Bluefurit and AdafruitSPIFlash libraries. This is my code:
#include <bluefruit.h> // Necessary for Bluetooth communication
#include <Adafruit_SPIFlash.h> // Necessary for FLASH memory management
Adafruit_FlashTransport_QSPI flashTransport; // Initialize flash communication device
Adafruit_SPIFlash flash(&flashTransport);
// Manufacturer IDs
#define XIAOMI_ID 0x0038F
#define APPLE_ID 0x004C
// Pin for sequential wake-up
#define WAKE_UP 2
// UUID for Beacon (fictional)
uint8_t beaconUuid[16] =
{
0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,
0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0
};
// Beacon creation for advertising
BLEBeacon beacon(beaconUuid, 0x0102, 0x0304, -54);
// Optimized function for advertising
void start_advertising(void) {
Bluefruit.Advertising.setBeacon(beacon);
Bluefruit.ScanResponse.addName();
// Increase interval for power savings
Bluefruit.Advertising.setType(BLE_GAP_ADV_TYPE_NONCONNECTABLE_SCANNABLE_UNDIRECTED); // No connection allowed
Bluefruit.Advertising.setInterval(160, 160); // Higher interval for power saving (units of 0.625ms)
Bluefruit.Advertising.setFastTimeout(1);
Bluefruit.Advertising.start(0); // Continuous advertising
}
// Optimized function for configuring clocks
void configure_clocks(void) {
NRF_CLOCK->LFCLKSRC = CLOCK_LFCLKSRC_SRC_RC; // Use internal oscillator directly
NRF_CLOCK->TASKS_LFCLKSTART = 1; // Start low-frequency clock
}
void setup() {
// Enable DC/DC converters
NRF_POWER->DCDCEN = 1;
NRF_POWER->DCDCEN0 = 1;
// Start low-frequency clock directly
configure_clocks();
// Initialize and put flash memory into deep sleep
flashTransport.begin();
flashTransport.runCommand(0xB9); // Enter deep sleep mode
flashTransport.end(); // End flash transport communication
// Initialize Bluefruit library
Bluefruit.begin();
Bluefruit.setTxPower(0); // Keep TX power at -20dBm
Bluefruit.autoConnLed(false); // Disable auto-connect LED
// Low-power temperature reading
int32_t temp = 0;
sd_temp_get(&temp);
int32_t real_temp = temp / 4;
// Set manufacturer ID and populate beacon with temperature reading
beacon.setMajorMinor(real_temp, 0);
// Start advertising
start_advertising();
delay(20);
// Configure GPIO for wake-up
nrf_gpio_cfg_sense_input(WAKE_UP, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW);
// Enter system-off mode for deep sleep
NRF_POWER->SYSTEMOFF=1;
}
void loop() {
// Empty loop
}
And this is the profile I see using the Power Profiler Kit 2 as source meter at 2200 mV:
