Ultra-Low Power Sensing Applications With CC13x2/CC26x2

This application report shows the low-power capabilities of the Sensor Controller Engine in the CC13x2 and CC26x2 devices. The current consumption of different sensors on the BOOSTXL-ULPSENSE is shown, as well as the current consumption of the different sensors of the LPSTK-CC1352R. Comparisons between similar tasks on the Sensor Controller and the System CPU are also shown.

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1 Overview

The CC13x2/CC26x2 devices comes equipped with a separate proprietary power-optimized CPU called the Sensor Controller. This CPU can read and monitor sensors or perform other tasks autonomously; thereby significantly reducing power consumption and offloading the system CPU.

Figure 1. CC13x2/CC26x2 System Block Diagram

The CC13x2/CC26x2 Sensor Controller peripherals include:

12-bit ADC capable of sampling analog capable I/Os or internal chip voltages.
Two comparators, one high performance continuous time comparator and one low-power clocked comparator updated at 32 kHz.
8-bit reference DAC capable of supporting the comparators with reference voltages.
SPI master interface.
Bit-banged interfaces including I²C master, LCD controller and more.
Time to digital converter capable of measuring the time between configurable start and stop triggers
Programmable current source capable of giving out currents between 0 and 20 µA.
Two simple 16-bit timers.
16-bit asynchronous multipurpose timer with 4 capture/compare channels.
16-bit pulse counter capable of count rising edges on any digital input pins or comparator output.
Access to all GPIO pins.

The Sensor Controller can be programmed from the software Sensor Controller Studio. This tool generates a Sensor Controller Interface driver, which is a set of C source files to be compiled into the System CPU application. These source files contain the Sensor Controller firmware image and associated definitions, and generic functions that allow the System CPU application to control the Sensor Controller and exchange data. Full documentation on how to use the Sensor Controller is documented in the Sensor Controller Studio itself.

The programming model and firmware framework are optimized for low overhead when communicating with the System CPU application, low AUX RAM memory footprint, and efficient use of the Sensor Controller's instruction set. To minimize power consumption, the Sensor Controller enters standby mode automatically when it is idle.