Issue 153 April 2003
E-Chips

KITCHEN SINK

Motorola always impresses me with the sheer amount of stuff they cram on their parts. Over the years, they’ve developed an impressive portfolio of silicon IP to draw from, which is a strategy that has paid off with the ability to quickly spin highly integrated chips. Check out the new MCF5282, and you’ll see what I mean (see Figure 1). 

First off, this is a true 32-bit MCU with a 66-MHz ColdFire V2 core complemented by a healthy 512 KB of flash memory and 64 KB of SRAM. If that’s not enough room for you, never fear, there’s a full-fledged 32-bit expansion bus to hang on extra memory chips.

Quite a bit of thought was put into maximizing memory bandwidth. After all, there’s no sense jacking up the clock rate if the end result is just more wait states. The basic flash memory access cycle is two clocks, but interleaving and speculative loads reduce the average below that. In any case, there’s also a 2-KB, direct-mapped cache that can be configured for code, data, or both. Of course, the SRAM, which can be used for code and data, delivers single-clock access.

What does the ’5282 have under the hood when it comes to peripherals? A better question might be: What hasn’t it got? Let’s see, there are four 32-bit timers, which are notable for excellent 15-ns resolution, and three UARTs, not to mention separate SPI and I²C clocked serial interfaces.

Apparently, the ’5282 never met a timer it didn’t like. In addition to the four 32-bit units, there are eight 16-bit timers with the requisite input capture, output compare, and PWM features. Throw in a watchdog and four periodic interrupt timers for the software guys, and that makes a grand total of…Oh, what the heck, who’s counting?

As I’ve said before, the ’5282 is a true microcontroller, and what MCU doesn’t come with an A/D converter these days? There’s nothing extraordinary about the raw specs for the ’5282 converter itself (i.e., 10-bit, 100-KHz), but it’s surrounded by an entire smart-queued subsystem that’s comprised of internal (eight-channel) or external (18-channel) multiplexing, automatic scan sequencing and timing, dedicated results RAM, and user-defined channel-control processing. 

It’s overkill if you just want to check a temperature sensor or potentiometer from time to time. But, for sophisticated analog processing, the QADC offers the promise of offloading the CPU of a huge amount of handholding. 

It’s all the better that the ’5282 also features an EMAC math accelerator that cranks 32 × 32 multiply results into a 48-bit MAC in a single clock. Unlike the early-out, two-bits-per-clock multiplier built into the  ColdFire V2 core, the EMAC is not only much faster, but the timing is completely deterministic, which is a must for signal processing.

Oops, I almost forgot the 10/100 fast Ethernet controller (FEC) that’s carried forward from the earlier MCF5272. At this point you shouldn’t be surprised to find that the unit features it’s own dedicated DMA (i.e., in addition to the chip’s four-channel, general-purpose DMA controller) and RISC sequencer.

Finally, yes finally, there’s even a controller area network (CAN) interface. The combination of CAN and Ethernet isn’t as odd as it may seem. Ethernet is poised to make a big move into industrial and factory-floor applications, and it may happen sooner than you think. 

The announced price for the ’5282 is $17.86 (10,000 quantity), which is higher than some, but arguably a bargain considering all the stuff that’s built in. Metrowerks (owned by Motorola) offers a combination of their popular CodeWarrior toolchain and an EV board for $600. Note that the package includes a royalty-free special edition of an RTOS and network stack (RTXC Quadros) that includes the basic network protocols. The more complete and configurable “Standard” and “Professional” editions cost $20,000 and $50,000 per project, respectively.

I also hear that Netburner has a ’5282-based module in the works, which is no surprise, because it easily leverages the know-how and tools of its ’5272-based design that I covered in my February column.