Texas Instruments CC2520 Development Kit

A Special DEV Kit Evaluation Series Editor's Choice

Jon Titus, Senior Review Editor -- EDN, 3/21/2009

New Information Added: 4 April 2009

In-depth Evaluation: Texas Instruments CC2520 Development Kit, Part Number CC2520DK. Texas Instruments, www.ti.com/CC2520dk. US$ 649.00.

Kit contents:

3 SmartRF05EB development baseboards
2 CCMSP-EM430F2618 MSP430 development boards
3 CC2520EM IEEE 802.15.4 radio boards with antennas
1 MSP-FET430UIF debug and programming module
4 USB cables
Quick Start Guide

This kit from Texas Instruments aims to help engineers move beyond basic wireless-device evaluations and into development work where they can write code and test wireless links. The radio boards operate in the 2.4 GHz Instrument, scientific, and Medical (ISM) band for unlicensed devices. (At present the kit does not comply with the technical regulations of the Radio Law of Japan.)

Engineers will find a lot of interesting hardware in this kit, but it falls short of the mark in documentation and tutorial information. Users might feel a bit overwhelmed because the documentation lacks step-by-step tutorials that would lead to a working project.

The Smart RF05EB board includes an LCD, push buttons, LEDs, a serial port and many I/O pins and headers. A battery holder on the back side accepts two AA cells for power. This "base board" accepts a CCMSP-EM430F2618 MSP430 development board that provides a "bare" MSP430F2618 microcontroller (MCU). The MCU board comes with I/O-port headers and a JTAG programming and debugging connector. A second add-on board, the CC2520EM, supplies an IEEE 802.15.4 radio.

Figure 1. The TI CC2520DK comprises three baseboards (foreground), three 2.4 GHz transceivers and antennas, two MSP430 MCU boards and a program/debug pod for the MSP430 chips. Courtesy of Texas Instruments.

I unpacked the kit, stacked the boards, and insert AA batteries. Users also can power the baseboard through a USB connection or with an external power supply (not supplied) that has an output between 4 and 10 volts DC.

After assembling the boards, I followed instructions to configure one board as a receiver and one as a transmitter. The latter will send a preset number of packets to the receiver, which counts the received packets in an error-rate test. I ran that test several times with the transmitter placed at three places in my office/lab. The received picked up all packets without errors.

Figure 2. Two complete "stacks" of battery-powered boards boards performed a packer-error-rate test. Boards were separated by about 20 feet (6 meters) for the test.

The Quick Start Guide points users to a page on the TI Web site that holds various documents:

LPRF Development Tools: SmartRF Studio Hands On User Guide
LPRF Development Tools: SmartRF Studio Overview
SmartRF Studio User Manual (Rev. 6.10.1)
CC2520 Sofwtare Examples: User\'s Guide.

I followed instructions in the "SmartRF Studio Overview" and downloaded and installed the SmartRF Studio software on my lab PC. I fought my way through the information, which hasn\'t caught up with the SmartRF05EB hardware and then wondered what I should try next. The "SmartRF Studio Hands On User Guide" provides some information, but as with the Overview document, it looks like a series of Powerpoint slides with the presenter\'s comments underneath. Engineers need step-by-step instructions for this kit, not a script for a classroom lecture. For the most part, the screen images are unreadable, but at least I got through the error-rate test.

I contacted TI\'s support people about the poor documentation and they referred me to the "CC2520 Development Kit User\'s Guide" (swru139) that offers more information--and clearer diagrams and images. The information includes MCU pin information, signal labels, and photos of jumper settings. Appendices provide schematic diagrams of the SmartRF05EB and CCMSP-EM430F2618 MCU board, but as usually, the diagrams printed lightly on my HP LaserJet 1100 and were almost impossible to read.

Sadly, the "Development Kit User\'s Guide" lacks key information and can cause confusion. First, each SmartRF05EB development baseboard has its own USB-controller MCU, a TI CC2511F32 chip. This MCU controls many functions on the baseboard and communicates with the MSP430 MCU on the add-on CCMSP-EM430F2618 board. The USB MCU controls the on-board I/O devices such as the LCD and joystick control. The MSP430 board can access these devices, but details are scarce or incomplete. So, users may wonder which MCU--the CC2511 or the MSP430--runs the show.

Apparently the CC2511 does the heavy lifting and communicates with the CC2520 wireless chip and the USB port that connects to a PC. You can program the CC2511 chip with your own code, but why bother? You get a better start if you use the CCMSP-EM430F2618 board and the CC2520EM board and do all your own programming for the MSP430 MCU vis the JTAG port. The SmartRF05EB has a lot of hardware, but without clearer documentation, you might be better off without it.

Figure 3. A 2.4 GHz CC2520EM board connects to a MSP430 MCU board and you can use with an MSP430F5438 Experimenter\'s Board, which you buy separately. TI does not provide a schematic for the CC2520EM boards, but the double-side PCB should make it easy to derive the circuit.

Second, a section describes the I/O ports and devices on the SmartRF05EB board, but only in general terms. The joystick control, for example, generates a JOY_MOVE signal and a JOY_LEVEL position voltage. But you must to look back a few pages to find pin-out information for the joystick connections to the USB MCU. And although the baseboard includes a 16-character, 3-line LCD, this device gets only a two-sentence description. The display communicates over an SPI bus and uses three control signals. One signal is noted as USB_LCD_FLASH_RESET in one place and as LCD Reset in another. Are they the same signal? Who knows.

The documentation lacks any code snippets that show how to control the display or other I/O devices. I found no source code for the CC2511 MCU software nor instructions on how to program a CC2511 MCU, although that task seems to take place via the USB port.

The SmartRF Studio GUI looks worth exploring and I bet it has many capabilities that could help engineers work with the hardware. Unfortunately TI doesn\'t supply a user\'s manual and tutorials that would explain what the software can do and how to use it. Apparently, this software will "export" C code that contains the necessary API commands to control something. The sketchy instructions never explain what, although I suspect the code will run on the MSP430 MCU. Or maybe it runs on the CC2511 MCU. Good luck figuring this out.

The SmartRF Studio software and an attached set of boards can act as a packet sniffer. Information claims this is the Sensor Network Analyzer from Daintree and you can find separate Daintree information on that company\'s Web site. Again, though, the kit documents lack any explanations of what this software can "sniff" and what it can tell you about a small wireless network.

To its credit, TI provides software examples users can compile and download to the MSP430 MCU through the supplied MSP-FET430UIF debug and programming module. Users can download a code-size-limited version of the IAR Embedded Workbench for MSP430 processors and use it to write and test code. The "kickstart" version of the IAR tools is free, but for serious development work, I recommend you buy a complete version.

The software examples include basic wireless communication tests as well as the packet error-rate application that comes preprogrammed in the MSP430 MCUs. The examples documentation is fair to good, but don\'t expect a step-by-step tutorial or lesson for each one. It\'s not always clear whether users program just one MSP430 MCU or all three. And although the document lists the various functions and hardware-abstraction-layer RF API functions, a bit more explanation would help users better understand how these functions operate. To set the RF output power, for example, use the function:

uint8 halRfSetPower (uint8 power)

It appears we have an 8-bit unsigned integer that sets the power level. But, what power levels can we choose and what 8-bit values correspond to the possible power levels? Perhaps the SmartRF Studio could provide this information, but it doesn\'t. It simply lists nine power levels from 5 to -18 dBm.

When I unpacked the CC2520 Development Kit I had high expectations. The hardware appeared to offer a good way to get wireless nodes up and running quickly. Initial tests with the preloaded code confirmed my assumption. When it came time to explore the software side of the kit, though, I wondered how easily engineers could plod through the spotty documentation and get any value from the SmartRF Studio tools or software examples.

Before I can recommend this kit as a solid platform for developers who want IEEE 802.15.4 communications, TI needs to offer a complete SmartRF Studio user\'s manual and step-by-step explanations of how to use the software\'s features. More sample source code would help, too. The "CC2520 Software Examples User\'s Guide" needs work, too. It supplies some helpful information, but there\'s a gap to fill between having developers simply run canned examples and giving them tutorials that teach them what to do and explains why they perform various development steps. Nowhere could I find a flow chart that describes the development steps an engineering team would go through with this kit, from the out-of-the box example up to their own simple application experiment. --Jon Titus

On 3 April, Poornima Shankar, a design engineer at Tyco wrote to let me know TI does provide a schematic of the CC2520EM boards, and engineers will find it at: focus.ti.com/docs/toolsw/folders/print/cc2520em_refdes.html Thanks, Poornima!

Jon welcomes comments about first-hand experiences using this or other wireless kits: "jontitus at comcast dot net".