Electronic Design

EiED Online>> IAR's STR730 Kit Delivers Solid ARM7 Development Platform

It's been a while since I checked out any of IAR's development kit offerings (EiED Online>> Developing ARMs, ED Online #11307) but my views on the company's products have not changed after checking out its latest ARM7 kit for STMicroelectronics' STR730: IAR delivers top-notch tools and platforms.

The STR730 Kickstart Kit is priced at about $300, but this includes the USB-based 12-MHz JTAG debugger (see the Figure). The latter has a small 5-V adapter board allowing power to be shared with the development board, up to 400 mA. External power can be provided if the board is used in a standalone configuration. The JTAG debugger can be utilized with other ARM7 and ARM9-based chips including support for multiple device scan chains.

The board has a 144-pin STR730FZ2 microcontroller based on a 32-bit ARM7TDMI core. Versions of the STR7xx chips are available for less than $5. The STR730FZ2 has 256 kbytes of flash and 16 kbytes (plus an extra 256 bytes) of SRAM. The kit comes with IAR's development, tools but the compiler has a 32-kbyte code limit. You need to buy a license for the full suite to remove the limitation. Still, this means the board provides a growth option that many other systems often lack.

The microcontroller can do some heavy duty lifting. It has a 16-channel DMA controller hooked into a dual APB bus architecture along with a four-channel 12-bit analog-to-digital converter (ADC). There are plenty of timers (16 PWMs) and I/O ports, but it is the communication side that is really impressive. There are three SPI ports (two available on the board), two I2C ports, four UARTs, and three CAN (two available on the board) ports. Other versions of the chip include USB support.

The chip is connected to 16 user LEDs, four pushbuttons and a two-line, 16-character/line LCD display. A potentiometer can be connected to one of the ADC channels.

ARM7 Out Of The Box

Getting the board up and running is relatively easy. The initial tutorial application is a simple LED flashing program. The Kickstart Guide (on the CD) covers this, incorporating it into a short tutorial using IAR Embedded Workbench and the JTAG unit.

The installation process is menu driven, but it is a multistep job. The license key must be downloaded from the IAR Web site. The IAR Embedded Workbench for ARM is installed separately from hardware-specific drivers. Still, it only takes a few clicks and a few minutes to get everything up and running.

I've looked at the IAR Embedded Workbench before. But for those new to the platform, it is one of the better C/C++ cross compiler and debugging systems around. It is polished and includes all the tools, including the C-SPY debugger, which is integrated with the J-Link USB JTAG unit.

The only deficiency I find in the kit is that you need to go to STMicroelectronics' site to gain access to the tech docs and application notes. It's a minor issue these days with broadband connections, though, and it does mean you will have access to the latest information and pricing. Developers will likely have little trouble handling most peripherals like the ADC and serial ports, but the CAN (controller area network) support is another matter. In general, CAN development often incorporates higher-level protocols like CiA (CAN in Automation) CANopen. You will have to look online or pick up a good book on CAN to learn how to use this, or CAN in general, since nothing in the kit addresses these kinds of topics.

One item in the package worth checking out is the graphical visualSTATE IDE. This C code generator uses a UML-compliant graphical design environment to create state diagrams that can be turned into code. The version that comes with the kit is limited to 20 states, but it is possible to create some rather sophisticated applications. Likewise, it is possible to utilize more than one state machine in an application, although any single instance will be limited. VisualSTATE has its own documentation and examples.

Getting started with STMicroelectronics' STR7xx family was a snap with IAR's Kickstart Kit. It's a neat chip that is ideal for a wide range of applications from process control to robotics. For more information, check out ARM, CiA (CAN in Automation), IAR Systems, and STmicroelectronics.

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