LaunchPad CC1350: How to Get Low Power Mode < 2.6 mA?

[rei-vilo]

The following Blinky sketch uses Energia MT with 2 clocks, and turns the LED on for 300 ms and off for 1700 ms.

EnergyTrace gives the following results:

• LED on: 30.9 mW or 8.7 mA
• LED off: 9.4 mW or 2.6 mA

When the LED is off, the CC1350 is idle (no tasks running) and thus should be in low power mode. However, it still uses 2.6 mA and battery life for a CR2032 is estimated to 2.2 days.

How to lower the low power mode consumption even further?

Sketch

#include "Galaxia.h"

Clock myClockOff, myClockOn;

void functionClockOn() {
  digitalWrite(GREEN_LED, HIGH);
}

void functionClockOff() {
  digitalWrite(GREEN_LED, LOW);  
}

void setup() {
  pinMode(GREEN_LED, OUTPUT);
  myClockOn.begin(functionClockOn, 100, 2000);
  myClockOff.begin(functionClockOff, 400, 2000);
  myClockOn.start();
  myClockOff.start();
}

void loop() {  
}

[rei-vilo]

The issue is just hidden inside loop(): it is empty, but it runs continuously.

The loop() function should include a yield mechanism, e.g. delay().

With just adding delay(1000); to the loop() function, the CC1350 only requires 0,039 mW or 0,011 mA when in idle or low power mode.

The error was so big and so obvious it was difficult to spot.

Instead of using delay(1000);, shouldn't be better to use something like yield();?

I'm thus closing the issue.