Thanks for you advice regarding the CR2032! I’ll keep an eye on it! I always disconnect the battery before connecting it to USB. Now, regarding the remaining digital pins, I cycled through them as you suggested. I did it without deep sleep by using pinMode(,INPUT_PULLUP) because I found that this is already sufficient to increase the current from around 5µA to above 30µA (it is a 2 or 3 µA variation day to day). It was only D2 that caused the current to increase. I tried it with a Li ion 18650 cell as well as the CR2032. The current is a bit higher with the Li ion cell (actually consistent with the higher cell voltage), but with both batteries the current increased by about 30µA with pinMode(D2,INPUT_PULLUP). I made this simple sketch to rule out a mistake in the timing of taking the current reading.
//----------------------------------------------------------------------------------------------
// BSP : Seeed nRF52 Borads 1.1.8
// Board : Seeed nRF52 Borads / Seeed XIAO nRF52840 Sense
//----------------------------------------------------------------------------------------------
// 2025/01/15
#include <Adafruit_SPIFlash.h> // 4.3.4, NOTE:need to deleted /Documents/Arduino/libraries/SdFat
#include <flash_devices.h>
// for flashTransport definition
Adafruit_FlashTransport_QSPI flashTransport;
Adafruit_SPIFlash flash(&flashTransport);
static const SPIFlash_Device_t my_flash_devices[] = {P25Q16H,};
const int flashDevices = 1;
void setup()
{
pinMode(LED_RED, OUTPUT);
pinMode(LED_GREEN, OUTPUT);
pinMode(LED_BLUE, OUTPUT);
digitalWrite(LED_BLUE, HIGH);
digitalWrite(LED_RED, HIGH);
digitalWrite(LED_GREEN, HIGH);
// Enable DC-DC converter Mode
NRF_POWER->DCDCEN = 1; // Enable DC/DC converter for REG1 stage
// on board Flash enter to Deep Power-Down Mode
flash.begin(my_flash_devices, flashDevices);
flashTransport.begin();
flashTransport.runCommand(0xB9); // enter deep power-down mode
delayMicroseconds(5); // tDP=3uS
flashTransport.end();
// Light Sleep Mode (RTOS delay function)
delay(10000);
while(true) {
digitalWrite(LED_BLUE, LOW);
delay(500);
digitalWrite(LED_BLUE, HIGH);
pinMode(D2, INPUT_PULLUP);
delay(5000);
pinMode(D2, INPUT);
digitalWrite(LED_RED, LOW);
delay(500);
digitalWrite(LED_RED, HIGH);
pinMode(D3, INPUT_PULLUP);
delay(5000);
pinMode(D3, INPUT);
}
}
void loop()
{
// nothing to do
}
@msfujino from your comment here on
#define PIN_WAKEUP (28) // D0:(2), D1:(3), D2:(28), D3:(29), D4:(4)
can I conclude that I could also use not only D3, but also D0, D1 and D4 to wake up? Any special considerations. I don’t know where I got this from, but I have in mind that only D2 and D3 can be used for interrupts. I have three buttons and it would be nice if any of them would wake up the device from deep sleep, but I could live with just D3 (if it works without immediate restart, which I’ll try next)