SensorTag CC1350

The CC1350 is a Cortex-M3 MCU with a dual-band radio, 2.4 GHz and sub-1 GHZ. The 2.4 GHz radio supports Bluetooth Low Energy and ZigBee.

The CC1350 SensorTag features the same rich assortment of sensors grouped around three categories: inputs, climate and IMU or inertial measurement unit, into a compact red box.

The CC1350 SensorTag was sampled by Texas Instruments.

Hardware

The CC1350 SensorTag has the same form-factor as the CC2650 SensorTag, and features the same connectors and sensors.

However, it includes only one red LED, instead of the two LEDs, red and green, on the CC2650 SensorTag.

The CC1350 SensorTag offers sensors similar to the Sensors BoosterPack used with the CC1310 / CC1350 LaunchPad.

However, there are slight differences. On the CC1350 SensorTag, climate measures imply two different sensors, while IMU measurements are provided by one single programmable sensor with data fusion and calculated Euler angles.

Here is the list of sensors:

HDC1000 humidity sensor by Texas Instruments,
BMP280 temperature and pressure sensor, by Bosch.
OPT3001 ambient light sensor by Texas Instruments,
TMP007 external and internal temperature sensor by Texas Instruments,
MPU-9250 9 DOF IMU sensor with built-in data fusion and angles calculation, by TDK Invensense.

Software

The CC1350 is supported by Energia MT.

This allows the use of RTOS elements brought by the Galaxia library like semaphores, mutex, clocks, events, tasks and more.

This platform is supported by embedXcode, embedded computing on Xcode.

Energia MT enters low power mode automatically when the scheduler has no tasks to run and the MCU goes into idle mode.

With no active tasks, the low power mode drops as low as 0.0505 mW or 0.0141 mA at 3.6 V.

A standard CR2032 coin cell battery provides around 200~250 mAh, which gives a battery life of more than one year.

This figure is consistent with the measures performed with EnergyTrace for the project Low Power Home Network Weather Monitoring.

For the weather sensors, the Weather Sensors Library for the Sensors BoosterPack only requires minimal adaptation.

However, results from the CC1350 SensorTag differ significantly from those measured by the Sensors BoosterPacks.

The following test was conducted with two CC1350 SensorTags (Nodes 1 and 2, top) and two CC1350 LaunchPads with Sensors BoosterPacks (Base and Node 3, bottom).

Some measures just can't be trusted, as they differ too much from one sensor to another.

Temperature: the BMP280 of the CC1350 SensorTags (Nodes 1 and 2) report 25 °C against 21 °C by the BME280 of the CC1350 LaunchPads with Sensors BoosterPacks (Base and Node 3).
Humidity: the HDC1000 of the CC1350 SensorTags (Nodes 1 and 2) report less than 40% against more than 60% by the BME280 of the CC1350 LaunchPads with Sensors BoosterPacks (Base and Node 3).
Pressure: surprise, all the sensors, both BPM280 and BME280, converge to 1014 hPa.
Light: the same sensor OPT3001 give slightly different values from the CC1350 SensorTags (Nodes 1 and 2) and the BME280 of the CC1350 LaunchPads with Sensors BoosterPacks (Base and Node 3).

Since the libraries are the same, do the sensors and the boards explain those significant differences? Obviously, testing only two items of each configuration isn't sufficient. We would need a large population for significant statistics.

In any case, the sensors would need to be carefully calibrated before being implemented them for real.

Conclusion

Although the CC1350 SensorTag is marketed as development kit, Texas Instruments recommends the the CC1310 / CC1350 LaunchPad over the CC1350 SensorTag for development.

However, both solutions do not share the exact same sensors, and provide significantly different results.

Additionally, the total cost is not the same. Adding the Sensors BoosterPack to the CC1310 / CC1350 LaunchPad sums USD54, while the CC1350 SensorTag with the Debug DevPack totals USD44.

At USD44 with its programmer, the CC1350 SensorTag brings tremendous value for an introduction to a local internet of things project like the Low Power Home Network Weather Monitoring.

Pros

Rich assortment of sensors
Great range
Energia MT support

Cons

Bluetooth stack not available for Energia
Energia needs to improve low power mode

Wrap-Up

Tremendous value
The perfect cost-effective introduction for local internet of things projects