The Texas Instruments eZ-Chronos Development Tool looks and works
like 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 cool
to wear and should be cool to use. The watch also includes a 3-axis
accelerometer, temperature sensor, pressure sensor and battery-voltage monitor.
PC-based software lets you monitor watch operations and set the time, alarm and
date, calibrate the temperature and pressure sensors, and log data.
Programmable options let wearers link to a nearby PC and control
mouse actions and PowerPoint presentations, if they wish. So after you use the
kit, you can still use it for something useful and fun. An optional heart-rate
monitor lets a wearer check his or her heart rate.
I received one of the first pre-release kits and rather than wait
for a CD-ROM that would normally come with a kit, I downloaded the latest
software from
TI's website. I also printed the
"eZ430-Chronos Development Tool User's Guide," SLAU292. A few pages
into the guide, TI provides a helpful list of related documents. The kit
includes a Quick Start flyer but the User's Guide includes more details and
step-by-step instructions about how to set the time and date before you move on
to wireless communications with a host PC.
The PC application software installed easily and plugging in the
USB wireless-access module brought up the usual USB-installation screens. (TI includes USB-driver installation
instructions in an appendix to the User's Guide.) Before you attempt to use the
watch in a wireless mode, install the PC software.
The first of three exercises shows how to obtain acceleration
information from the watch via the wireless link and then display 3-axis
acceleration graphs on a PC. Several attempts failed to obtain the acceleration
information. I saw the wireless module flash a green LED several times, but the
wireless communications didn't occur. I used Windows' Device Manager to
determine the PC recognized the wireless module, but "saw" it as a
serial-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 the
User's Guide didn't provide it. A help
screen in the PC software listed serial-port settings as: 115200 baud, 8 data
bits, 1 stop bit, no parity and no control flow. After I changed the port
settings to those values — and put the watch in the proper mode — I could see
the acceleration versus time plot for all three axes. I skipped the mouse and
PowerPoint exercises.
The rest of the User's Guide explains how to use the watch
functions and how to disassemble it and connect it to the USB debug module. Reference
information 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 CCS
v4
here. Look for the free TMDFCCS-MCULTD version for
the MSP430 microcontrollers. You
register and TI sends you a link to download the code.
The eZ430-Chronos kit comes in several versions; one that
operates 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 two
versions, too, so download the one that matches your kit and geographical area.
If you're more familiar with the IAR Embedded Workbench, download KickStart
versions — also with 16-kbyte code limits — for the U.S.
or Europe. (This development kit is NOT
certified as conforming to Technical Regulations of Radio Law of Japan.)
Instructions in the User's Guide explain how to use CCS or IAR
Embedded Workbench to open either the sports watch or a data-logger program
used by the CC430F6137 MCU. I followed the instructions to build the project,
but that's as far as the instructions go. These "default" projects
take almost all of the MCU's Flash memory and cover a lot of pages of printed
code. I tried unsuccessfully to go through some of the sports-watch code to
understand how the program works and perhaps how I could adapt the code to do
something basic.
As an "early adopter" I missed some late information
now posted on TI's website: TI now
provide many snippets of code for the eZ430-Chronos. According to TI, "The
code examples are a series of ~100 sample programs written in C that
demonstrate several ways to configure each of the peripherals on the CC430.
Using CCS or IAR, each file can be downloaded directly to the device or
snippets from each example can be combined to achieve your desired function."
The package of examples includes a helpful readme.txt file that
describes what each code snippet does. For the code-example package, click
here
and find the heading, CC430F6137 Code Examples, about halfway down the page. According
to Adrian Valenzuela, product marketing engineer for the MSP430 MCUs, TI plans
to create a set of projects that lie somewhere between the code snippets and
the firmware that comes in the watch. That sounds like a good plan.
TI's website Wiki for the EZ430-Chronos goes through regular
updates and includes comments from users, so check it for the latest
information. The company also welcomes contributed projects and code.
At this point, the eZ430-Chronos Development Tool looks like it
could provide an interesting way to learn about the CC430F6137 MCU and its
wireless communication capabilities. I felt stymied, though, by the lack of
follow-on projects that took a step-by-step approach to a few simple
applications, such as creating a four-digit counter, exchanging a few bytes via
the wireless channel, and so on. For
now, the code-snippet package could suffice for hard-core developers.
Disassembly
Because TI did not have example programs when I reviewed the
eZ430-Chronos development tool, I did not connect the watch to my lab PC
through the USB debug module. But it seemed worthwhile to disassemble the watch
and have a look inside. Use the small screwdriver to remove the four screws on
the back. If you lose screws, two extras come in the kit. You can easily remove
the watch module, but removing the battery takes skill. The User's Guide
instructions help a bit. I used a clip-on magnifier to see better and a small
jeweler's flat-blade screwdriver to push the tab on the loose end of the
battery clip. That released tension and the battery slid out. DO NOT connect the watch module to the USB
debug module with the battery still installed.
My watch went back together easily.
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Removing the battery turns off power and the watch requires
resetting. Instead of fooling with the watch buttons, use the PC application to
set the time, date, temperature, altitude and metric or English units. Then
send the new settings to the powered watch.
Click
here for more information.
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