Kit Spans 8- And 32-bit Microcontrollers

Sept. 26, 2007
Freescale Flexis line melds 8- and 32-bit processor lines into pin compatible chips. Technology editor Bill Wong takes a look at DEMOQE128 system that highlights both ends of this spectrum.

Freescale is highlighting its new Flexis line of microcontrollers with its $99 DEMOQE128 platform, a low-cost development system includes a base board and a pair of processor modules — one 8-bit and one 32-bit. The base board can ber powered off a pair of AAA batteries or a USB cable (both included), the latter of which provides a debug interface. What is Flexis? Flexis is a product line from Freescale that incorporates a set of 8- and 32-bit microcontrollers. Pairs of 8- and 32-bit chips will share pin-outs and peripheral interfaces. The first two chips in the family are the MC9S08QE128 (8-bit) and MCF51QE128 (32-bit). The 8-bit parts are based on an S08 core while the 32-bit parts are based on a ColdFire V1 core. Freescale will continue to maintain a set of parts for other microcontroller families, but designers that choose the Flexis line have an opportunity to increase the potential migration breadth not possible with another product line. This approach allows a designer to step up to a 32-bit part if computational requirements grow, or to move down to an 8-bit part if an application can fit into a more compact framework. Of course, there are limits on this approach. In particular, the peripheral set in the family must be consistent so application-related device drivers can migrate between 8- and 32-bit targets. It is unlikely that high performance interfaces such as SATA and PCI Express will ever wind up in this family but they are readily available in higher end Freescale platforms. Common peripheral architectures is only part of the game; development software is also important. Essentially, it means having a single development platform for both 8- and 32-bit code. Likewise, transition between the two should be a minor matter. Most vendors taking a similar approach may utilize the same peripheral approach but they have typically failed when it comes to software leaving the onus on the programmer. The DEMOQE128 Hidden on the back of the base board is a 16-bit Freescale MC9S12UF32PUE microcontroller that provides the Multilink USB-based debugging interface to the Flexis microcontroller. The Flexis modules plug into standard dual-row headers and essentially bring out all the peripheral interfaces. These are routed through jumpers to on-board devices like LEDs, as well as to a connector on the rear of the unit that allows for expansion to external devices. This provides a nice low-end development environment in addition to something suitable for higher-end applications via external devices. Switching between 8- and 32-bit hosts is just a matter of swapping modules. Additional Flexis chips are expected in this module format as well. The board routes module SCI signals to Multilink through jumpers providing a virtual serial port link. Likewise, Multilink is connected to TPM signals that can record information via the on-board logic analyzer. On-board peripherals include 8 LEDs, 4 push buttons, a 3-axis accelerometer, a piezzo buzzer and an RS-232 serial port. There is also a 10K POT for analog testing. Janus Software No, it is not quite two-faced but the version of CodeWarrior included with the DEMOQE128 does support the 8- and 32-bit platforms. Assembler code is different because these are distinct architectures but most developers will utilize C or C++, thereby hiding the architectures. The installation DVD also includes the same software and docs for the EVQE128, the more expensive, more extensive development platform, plus tech specs for both processors. In addition to CodeWarrior Development Studio for Microcontrollers 6.0, the DVD includes a couple training videos and links to web-based support. The videos are well done and walk through exercising the systems using the training software. They show off-board features like the built-in logic analyzer and 3-axis accelerometer. Freescale has done an excellent job in delivering seamless, almost automatic migration between 8- and 32-bit microcontrollers. It is literally a few mouse clicks to switch between targets. I was able to write an application once and run it on either platform without any change to my code including direct manipulation of peripherals. Just stick with high-level code. It is especially handy when writing device drivers. Overall, this system is a bargain. The software package is impressive and the ability to check out two different processor platforms using the same hardware is unmatched by other solutions. If the Flexis line fits your requirements, this is an excellent way to get started with the family. Related Links Freescale Semiconductor


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