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Sleep frequency - 999ms vs. 1000ms

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running this blinking led code on Launchpad MSP430FR2433

// Ultra Low Power Blink Example

#define LED RED_LED
void setup() {                
  for (int i = 2; i < 20; i++) {
      if (!(i == 11 || i == 12)){
        pinMode(i, OUTPUT);
        digitalWrite(i, LOW);

void loop() {
  digitalWrite(LED, HIGH);   // turn the LED on (HIGH is the voltage level)
  digitalWrite(LED, LOW);    // turn the LED off by making the voltage LOW

resulting in this current profile:


The power consumption looks nice (with LED current limited via 3.3 kOhm) but the blinking frequency is rather 10 seconds instead of 2 seconds.

The launchpad is configured to run with external crystal.

Changing sleep(2000) to sleep(999) I got the following profile:


The frequency is now OK but I am not sure if the same LPM mode is achieved during sleep phase.

Please, could someone give an insight about the difference? Can I run 2s blink frequency with ~1µA consumption during sleep phase?

Thanks in advance,


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