Choosing another wireless microcontroller with sensors

I want to connect wireless sensors to a BLE enabled device like a smartphone or tablet. I am also interested in long range/low volume sensor data transmission (Sub-1GHz).

The Simplelink CC1350 SensorTag Bluetooth and Sub-1GHz Long Range Wireless Development Kit is a tiny board based on the CC1350F128RGZT. I like it because of:

the small footprint (32 x 41 mm) allowing for integration in an existing project (for example via UART) thus enabling BLE/Sub-1GHz connectivity without having to deal with RF board design,
the comprehensive set of available sensors.

Getting started with the SensorTag wasn’t as easy as I hoped and this is a write-up of the problems I encountered.

Source code related to this note can be cloned from the compagnion repo.

1. Introduction

The name CC1350STK is the official part number for the development kit, I will also use the term SensorTag hereafter. A similar product SimpleLink™ Bluetooth low energy/Multi-standard SensorTag CC2650STK with single-band capability is also available Getting started with the TI SensorTag CC2650.

2. Problems

The problems encountered and discussed on the TI E2E™ support forums revolve around several topics:

the SensorTag App [e2e1], [e2e2], [e2e6]
installation problems [e2e11]
software availability [e2e9]
choice of the debug probe [e2e4], [e2e5], [e2e8]
project configuration files [e2e4], [e2e8], [e2e12]
connection problems [e2e4], [e2e10]

3. Hardware Preparation and Requirements

I used the following hardware:

the Simplelink CC1350 SensorTag Bluetooth and Sub-1GHz Long Range Wireless Development Kit
the XDS110 JTAG Debug Probe (not supported, as it turned out) and the SimpleLink SensorTag Debugger DevPack

and the following software;

Linux Mint 18.2
Code Composer Studio 9.1 (CCS)
SimpleLink CC13x0 SDK, version 3.20.0.23 [st-sw3]

The Sensor Tag comes with a lithium coin cell. For development, I prefer a stable lab power supply:

Figure 1. The CC1350STK without coin cell slot ready for an external supply (1.8V - 3.8V)

Do not leave the coin battery inserted during debugging. The battery will be drained in less than a day.

3.1. Using the XDS110 debug probe

The XDS110 JTAG Debug Probe can be hooked up to the SensorTag via a JTAG cable and a small adapter board.

while the connection between the probe and the SensorTag is electrically correct, I was unable to get the XDS110 to work in with the SensorTag.

Figure 2. JTAG connection between the XSD110 debugger and the CC1350STK ( the small adapter PCB is part of the XDS110 deliverable)

3.2. Using the SensorTag DevPack

The SimpleLink SensorTag Debugger DevPack is the recommended probe for the SensorTag.

Figure 3. The DevPack probe mounted onto the CC1350STK

Remove the coin battery, it will be quickly drained by the debug connection.

4. Loading the sample project

I used the uartecho_CC1350STK project because it not only serves as a basic sanity check for the environment but also as a proof that the serial-over-USB host-target connection works as expected.

Download and install the project from the Resource Explorer:

Figure 4. Loading the sample project into the IDE

Verify that the required products are installed and selected:

Figure 5. Required products

Verify the target configuration:

Figure 6. Target configuration

And the debug settings:

Figure 7. Debug settings

Ready to start the first debug session with the uartecho_CC1350STK_tirtos_ccs sample project. The companion tutorial Getting started with the TI SensorTag CC2650 shows how to activate ../3-CC2650-ST/index.html with the System Analyzer for the CC2650 SensorTag. The procedure is the same for the CC1350STK.

5. Conclusion

The SensorTag is not a full blown development kit and there is a reason why the product page Simplelink CC1350 SensorTag Bluetooth and Sub-1GHz Long Range Wireless Development Kit recommends to use a suitable LaunchPad rather than the SensorTag for development. However, the corresponing LaunchPad has a much larger footprint and no sensors, therefore the SensorTag can provide value for small projects and prototypes where dual BLE/Sub-1GHz connectivity and additional sensors are desirable.

6. References

Technical Documents

[td1] CC1350SimpleLink™ Ultra-Low-PowerDual-Band Wireless MCU

More literature

[ml2] TI 15.4-StackCC13x0 SimpleLink™ Embedded Example Applications

Development Tools

Software

[sw1] SimpleLink™ CC13x0 SDK 2.20.00.38 Documentation Overview

TI E2E support forum

dicussions started by the author

[] CC2650STK: SensorTag doesn’t show up in device list of TI SensorTag App
- choosing the right app: the flyer in the box mentions an app that is not available anymore, the SimpleLink SensorTag on Google Play is the correct one, although the CC2650STK is not part of the SimpleLink family
- granting permissions: for some reason you must grant access to your phone’s location. This is not only annoying because this is supposed to be demo software, but also the app doesn’t work without warning if you don’t grant access.
- also applies to the CC1350STK.
[] CC2650STK: Cloud Settings for the IBM IOT platform for BlueMix Free
- currently the IBM Watson IoT platform access (as opposed to the IBM Quickstart access) is not available with the SimpleLink SensorTag app due to a bug.
- also applies to the CC1350STK.
[] CC2650STK: Is there a linux compatible BLE stack for the CC2650STK
- no, this is one of the idiosyncrasies of the CC2650STK, refer to the SimpleLink™ Bluetooth low energy/Multi-standard SensorTag CC2650STK for a Linux compatible BLE development environment.
[] CCS/CC2650STK: Failed to launch debug session for CC2650STK
- contrary to what the discussion suggests, the target configuration of the uartecho_CC2650STK project is correct, no modification is required.
- contrary to what the discussion suggests, the XDS110 JTAG Debug Probe is currently not supported for the Sensor Tags, use the SimpleLink SensorTag Debugger DevPack.
- contrary to what the discussion suggests, the coin battery must not be inserted during debugging, the target is powered by the SimpleLink SensorTag Debugger DevPack.
- also applies to the CC1350STK.
[] CCS/CC2650STK: Can I use CCS and the XDS110 debug probe to program and debug the CC2650STK SensorTag
- while it is possible to connect the XDS110 JTAG Debug Probe, see Figure XDS110 connection, this debug probe is currently not supported for the Sensor Tag.
- also applies to the CC1350STK.
[] CC1350STK: Downloading new firmware images to the device via the Over-the-Air-Download (OAD) service not as described in doc
- this is currently an open question for the SimpleLink SensorTag app team.
- also applies to the CC2650STK.
[] CCS/CC2650STK: Can’t start the System Analyzer despite the README.md saying so
- see chapter [logging]
- applies to all TI-RTOS based projects.
[] CC2650STK: Can’t use UART on CC2650 STK
- this was due to the usage of the XDS110 JTAG Debug Probe debug probe in conjunction with the suggested modification of the target configuration file in [e2e5].
- also applies to the CC1350STK.
[] CC1350STK: Where is the out-of-box demo source code for the CC1350 and CC2650 Sensor Tags ?
- the out-of-box demo source code is not available. Why ?
- also applies to the CC2650STK.
[] CCS/CC1350STK: Empty project debug session not as expected
- I am unable to reproduce the errors mentioned. I suppose that they were related to the usage of the XDS110 JTAG Debug Probe rathern than the SimpleLink SensorTag Debugger DevPack.
- also applies to the CC2650STK.
[] CCS/CODECOMPOSER: Code Composer Studio 9 Installer hangs on Windows 7 SP1
- installing the CC13x and CC26xx device support on Windows 7 Pro fails, this is a bug related to the TI emulator driver installation.
[] CCS/CC1350STK: Setting for Power Selection for CC1350STK and for CC2650STK
- the power selection in the target configuration files of the example projects are correct, when using SimpleLink SensorTag Debugger DevPack. The battery/power supply must be removed during debugging.
- also applies to the CC2650STK.