The LabRat: Strap on a TI Dev Tool

DN Staff

February 5, 2010

6 Min Read
The LabRat: Strap on a TI Dev Tool

The Texas Instruments eZ-Chronos Development Tool looks and workslike a sports watch, but inside it offers engineers an MSP430-class MCU(CC430F6137), a short-range RF link, pushbuttons and an LCD. So the kit is coolto wear and should be cool to use. The watch also includes a 3-axisaccelerometer, temperature sensor, pressure sensor and battery-voltage monitor.PC-based software lets you monitor watch operations and set the time, alarm anddate, calibrate the temperature and pressure sensors, and log data.

Programmable options let wearers link to a nearby PC and controlmouse actions and PowerPoint presentations, if they wish. So after you use thekit, you can still use it for something useful and fun. An optional heart-ratemonitor lets a wearer check his or her heart rate.

I received one of the first pre-release kits and rather than waitfor a CD-ROM that would normally come with a kit, I downloaded the latestsoftware from TI's website. I also printed the"eZ430-Chronos Development Tool User's Guide," SLAU292. A few pagesinto the guide, TI provides a helpful list of related documents. The kitincludes a Quick Start flyer but the User's Guide includes more details andstep-by-step instructions about how to set the time and date before you move onto wireless communications with a host PC.

The PC application software installed easily and plugging in theUSB wireless-access module brought up the usual USB-installation screens. (TI includes USB-driver installationinstructions in an appendix to the User's Guide.) Before you attempt to use thewatch in a wireless mode, install the PC software.

The first of three exercises shows how to obtain accelerationinformation from the watch via the wireless link and then display 3-axisacceleration graphs on a PC. Several attempts failed to obtain the accelerationinformation. I saw the wireless module flash a green LED several times, but thewireless communications didn't occur. I used Windows' Device Manager todetermine the PC recognized the wireless module, but "saw" it as aserial-port device, not as a USB device. Windows lists the serial port as: TI CC1111 Low-Power RF to USB CDC Serial Port(COMxx) in the Device Manager window.

The serial port likely needed some setup information, but theUser's Guide didn't provide it. A helpscreen in the PC software listed serial-port settings as: 115200 baud, 8 databits, 1 stop bit, no parity and no control flow. After I changed the portsettings to those values a euro " and put the watch in the proper mode a euro " I could seethe acceleration versus time plot for all three axes. I skipped the mouse andPowerPoint exercises.

The rest of the User's Guide explains how to use the watchfunctions and how to disassemble it and connect it to the USB debug module. Referenceinformation includes schematic diagrams, board layouts and bills of materials,but no development experiments, programming exercises or code samples. Even without those, I plowed ahead.

I downloaded the Core Edition of TI's Code Composer Studio (CCS)v4 integrated development environment that has a 16-kbyte code limit. Find CCSv4 here. Look for the free TMDFCCS-MCULTD version forthe MSP430 microcontrollers. Youregister and TI sends you a link to download the code.

The eZ430-Chronos kit comes in several versions; one thatoperates at 915 MHz for U.S.developers and one that operates at 868 MHz for European developers. Thus, the-915 at the end of the model number for this kit. The CCS comes in twoversions, too, so download the one that matches your kit and geographical area.If you're more familiar with the IAR Embedded Workbench, download KickStartversions - also with 16-kbyte code limits - for the U.S.or Europe. (This development kit is NOTcertified as conforming to Technical Regulations of Radio Law of Japan.)

Instructions in the User's Guide explain how to use CCS or IAREmbedded Workbench to open either the sports watch or a data-logger programused by the CC430F6137 MCU. I followed the instructions to build the project,but that's as far as the instructions go. These "default" projectstake almost all of the MCU's Flash memory and cover a lot of pages of printedcode. I tried unsuccessfully to go through some of the sports-watch code tounderstand how the program works and perhaps how I could adapt the code to dosomething basic.

As an "early adopter" I missed some late informationnow posted on TI's website: TI nowprovide many snippets of code for the eZ430-Chronos. According to TI, "Thecode examples are a series of ~100 sample programs written in C thatdemonstrate several ways to configure each of the peripherals on the CC430.Using CCS or IAR, each file can be downloaded directly to the device orsnippets from each example can be combined to achieve your desired function."

The package of examples includes a helpful readme.txt file thatdescribes what each code snippet does. For the code-example package, click hereand find the heading, CC430F6137 Code Examples, about halfway down the page. Accordingto Adrian Valenzuela, product marketing engineer for the MSP430 MCUs, TI plansto create a set of projects that lie somewhere between the code snippets andthe firmware that comes in the watch. That sounds like a good plan.

TI's website Wiki for the EZ430-Chronos goes through regularupdates and includes comments from users, so check it for the latestinformation. The company also welcomes contributed projects and code.

At this point, the eZ430-Chronos Development Tool looks like itcould provide an interesting way to learn about the CC430F6137 MCU and itswireless communication capabilities. I felt stymied, though, by the lack offollow-on projects that took a step-by-step approach to a few simpleapplications, such as creating a four-digit counter, exchanging a few bytes viathe wireless channel, and so on. Fornow, the code-snippet package could suffice for hard-core developers.

Disassembly

Because TI did not have example programs when I reviewed theeZ430-Chronos development tool, I did not connect the watch to my lab PCthrough the USB debug module. But it seemed worthwhile to disassemble the watchand have a look inside. Use the small screwdriver to remove the four screws onthe back. If you lose screws, two extras come in the kit. You can easily removethe watch module, but removing the battery takes skill. The User's Guideinstructions help a bit. I used a clip-on magnifier to see better and a smalljeweler's flat-blade screwdriver to push the tab on the loose end of thebattery clip. That released tension and the battery slid out. DO NOT connect the watch module to the USBdebug module with the battery still installed. My watch went back together easily.



Removing the battery turns off power and the watch requiresresetting. Instead of fooling with the watch buttons, use the PC application toset the time, date, temperature, altitude and metric or English units. Thensend the new settings to the powered watch.

Click here for more information.

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