Launchpad SensorTag Kit CC1352R

The CC1352 is a Cortex-M4F MCU with a dual-band radio, 2.4 GHz and sub-1 GHZ. The 2.4 GHz radio supports Bluetooth Low Energy, ZigBee, OpenThread, 802.15.4.

​This is the third generation of SensorTag, after the CC2540 SensorTag and the SensorTag CC1350. This line is closer to a finished product than a development board.

The Launchpad SensorTag kit CC1352R, or LPSTK-CC1352R for short, 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 LPSTK-CC1352R was sampled by Texas Instruments.

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Everything inside the kit

Hardware

The kit comes with an enclosure, a SWD 10-way flat cable, two cables for serial console and an antenna for sub-1 GHz radio.

The LPSTK can be powered through the SWD cable, by 2 AAA batteries or optionally by a CR2032 coin-cell. The last option requires soldering a battery holder to be bought separately.

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​The four parts of the enclosure
The Launchpad SensorTag kit CC1352R offers sensors similar to the Building Automation System Sensors used with the CC1352 LaunchPad. However, the IR thermometer is removed and a 3-axis accelerometer is added.

Here is the list of sensors:
  • HDC2080 humidity and temperature sensor by Texas Instruments,
  • DRV5032 Hall-effect switch by Texas Instruments,
  • OPT3001 ambient light sensor by Texas Instruments,
  • ADXL345 3-axis accelerometer by Analog Device.

Compared to the previous iterations of the SensorTags, the 9 DOF IMU is reduced to a 3-axis accelerometer, and the ambient sensors no longer include the barometer and the external IR thermometer.

Expandability with 40-pin connector

The Launchpad SensorTag kit CC1352R inaugurates a new form-factor with 40-pin connector so it can be expanded with the BoosterPack boards to plug-in on top. 

Programming is done through a standard 2x5 SWD connector. The programmer part of a CC1352R LaunchPad can be used to upload and debug. The kit includes the SWD flat cable and two extra cables for the serial console.

​Three power sources are possible: either two AAA batteries or a CR2032 coin-cell, although the holder is not supplied with the kit and needs to be purchased separately then soldered onto the board. A jumper selects between the two AAA batteries and the CR2032 coin-cell battery. A slider button turns the board on and off.
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Despite the 40-pin connector, expandability is limited, as some of pins on the 1-20 range are already used for the sensors of the LPSTK:
  • Pins 2 for hall-effet sensor input, 
  • Pin 8 for blue LED output,
  • Pin 11 is not connected,
  • Pins 12 and 13 for push buttons 1 and 2 inputs,
  • Pin 18 for accelerometer chip select output, when the standard sets it for radio.
A simple and elegant solution would have consisted on allocating those GPIOs on the range 21-40, and thus freeing the 1-20 range for the BoosterPack boards. 
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The ​Sharp Memory LCD BoosterPack 128 was a candidate of choice as screen for the Launchpad SensorTag kit CC1352R. Alas, major conflicts on pins allocations make it unsuitable.
  • Pin 2 is used as power for the Sharp display and hall-effet input by the LPSTK. 
  • Pin 8 is /CS input for the SD-card of the Sharp display and blue LED output on the LPSTK;
  • ​The alternative for the SD-card /CS input is pin 12, alas used as PUSH2 input by the LPSTK.​

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Don't try this before modifying the screen
As possible solutions,
  • The issue on pin 2 can be circumvent by removing R7 and soldering R5, so power is provided directly by 3.3V.
  • The alternative for pin 8 is even worse, as the conflict on pin 12 can't be solved. So keeping pin 8 for SD-card /CS input makes the blue LED unusable.
However, as resistors are SMD, removing R7 and soldering R5 require the corresponding equipment.

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Spot the differences!

Pins Maps

As for other LaunchPad and BoosterPack boards, two pins maps are available:
  • The standard pins allocation map,
  • A connection map to the XDS110 programmer and serial console.

Software

The module comes with a pre-flashed OOTB demo, that collects and sends data to the Android and iOS apps through BLE.
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​There are multiple SimpleLink apps available: make sure to pick the right one, here Starter.
New binaries can be uploaded over-the-air through Bluetooth.
The two radios, sub-1 GHz and 2.4 GHz, support a wide range of protocols, including
  • Sub-1 GHz EasyLink and 802.15.4, 
  • 2.4 GHz Bluetooth Low Energy, Thread, Zigbee and 802.15.4.

The SimpleLink™ CC13x2 and CC26x2 software development kit (SDK) provides the corresponding stacks and libraries.
The CC1352R features a complex mechanism, called BIM for Boot Image Manager, to protect the Flash from being modified. By default, the boot-loader loads and runs the executable stored in the external flash.

​This means that programs uploaded with Energia and stored in the internal Flash are not considered by the boot-loader. A specific procedure is needed to unlock this feature and run custom application on the LPSTK. 
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The CC1352 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 also supported by embedXcode, embedded computing on Xcode, with external debugging performed through an XDS110 or a Segger J-Link programmer.
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​​Sadly, the technical documentation is only available as website pages and not in PDF format for offline reading. Similarly, documentation mainly consists on SimpleLink Academy examples, not a reference user guide. Removing the BIM protection requires digging into multiple sub-pages, apart from loading external tools.
Not yet ready for prime-time

Conclusion 

The Launchpad SensorTag kit CC1352R provides a compact form-factor with expandability thanks to the standard 40 pins. 

The LPSTK requires an external programmer-debugger, most of the time from a CC1352R LaunchPad used as central hub. The SDK supports the dual radio and provides multiple protocols.

However, expandability is limited as the LPSTK uses pins 1-20 for internal sensors and thus excludes many BoosterPack boards because of interferences.

End-user expectations are higher, as the LPSTK is closer to a finished product than a development board. The documentation doesn't include a reference user guide and is not available for off-line reading.

Pros

  • Rich assortment of sensors​
  • Dual radio and multiple protocols
  • Expansion with BoosterPack boards
  • Energia MT support

Cons

  • Flash protected by default, specific procedure to use another application
  • Incompatible with the Sharp screen
  • Bluetooth stack not available for Energia​
  • No reference user guide, no off-line documentation 

Wrap-Up

  • Compact and expandable
  • Cost-effective introduction for dual-band home automation projects
  • Dual radio and multiple protocols

Links
​Posted: 27 December 2019
​Updated: 22 Feb 2021