Review
Microcontrollers represent a highly splintered market, with the MCUs going into a broad array of consumer, commercial, industrial and automotive products. But regardless of application, new MCUs offer, more often than not, marked reductions in power dissipation, flash memory and interface circuitry on-chip. In fact, rare is the new MCU that doesn't support operation at 3.6V or lower and that doesn't have at least several kilobits of flash, with CAN (controller area network), I2C, SPI, USB, and Ethernet being among the more frequent interfaces encountered on the chips. To these advances must be added a host of other features found on today's micros. Here is a quick glance at controllers published in EEPN over the past several months that underscore these trends.
On-chip Ethernet and CAN networking interfaces and 512 KB of embedded flash are seen helping Motorola's MCF5282 32-bit MCU (motorola.com/semiconductors) make inroads into markets for industrial networking, home automation and security products. The controller includes the software for networking functions, as well as 64 KB of SRAM, an 8-channel, 10-bit queued ADC, four 32-bit timers with DMA capability, and a host of other features.
The eZ80 family from Zilog's stable of 8-bit microcontrollers (zilog.com) provides up to 256 KB of reprogrammable flash and Ethernet MAC and TCP/IP protocols, with one family member capable of operating at clock speeds up to 50 MHz and performing 24-bit integer math. Among other features found on-chip are an infrared encoder/decoder, two UARTs with independent baud-rate generator, an I2C bus with clock generator, and a SPI with its own clock rate generator.
In a reported first, Oki Semiconductor (okisemi.com/us) has melded on-chip ARM7 and Teak DSP cores with a MP3 audio processing engine. The ML675200 comes in ROM-less and 256 KB flash versions, with both devices also packing 32 KB of SRAM.
EM Microelectronic's EM6635 RISC microcontroller (emmicroelectronic. com) operates on 1.2V to 3.6V, with active current consumption being 1.5 µA at 1.55V/32 MHz; in standby mode, only 0.4 µA is used. The device also features nine high-current I/Os and the equivalent of 8 KB of ROM.
Other novel MCUs that simplify designs and reduce board real estate requirements are Microchip Technology's (microchip. com) rfPIC12F675K/ F/H PICmicro devices. Melding on-chip an MCU with UHF transmitters, the 20-pin devices can deliver output power of 6 dBm over three frequency ranges: 260 to 350 MHz; 390 to 450 MHz; and 850 to 930 MHz.
And introduced as the industry's first system-on-a-chip MCU for electronic energy meters, the MSP430FE- 42x family from Texas Instruments (ti.com) combines a flash MCU with an analog front-end (AFE), with this level of mixed-signal integration promising to reduce chip counts by up to 80%. Features include an embedded signal processor (ESP), three 16-bit sigma-delta a/d converters operating at 1 MHz, three programmable gain amplifiers, temperature sensor, and a precision voltage reference. Operating on 3V, power consumption with the CPU and ESP active is 2.5 mA and 1.1 µA in standby with the real-time-clock function active.
—Joe DelGatto
Outlook
Advances On All Fronts
Across the entire spectrum of microcontrollers, the immediate future will see further reductions in power dissipation, larger blocks of memory—especially flash memory—stored on-chip, and increased emphasis on tailoring MCUs to fit large and small marketplace niches. To reduce power consumption, working voltages for MCUs will continue to migrate from 5V to 3.3V to well under 2.0V. And power management circuitry of varying degrees of sophistication will be brought on-chip with increasing frequency to extend battery runtime in MCU-equipped portable devices. Controllers will also enter the marketplace over the next several months offering faster operating speeds, wider operating temperature ranges, increased quantities of I/O, easier-to-use debugging capabilities, and a broader range of interfacing features. In the MCU arena, the next year promises to deliver something for just about everyone.
—JDG
