Cirrus spins general-purpose processor for Net
audio players
Junko Yoshida
EE Times
(06/07/99, 10:27 a.m. EDT)
FREMONT, Calif. — Spurred partly by the Secure Digital Music Initiative's
(SDMI) circulation of its draft technical specs among its membership,
consumer-electronics manufacturers are parting with tradition to
contemplate general-purpose-microprocessor-based solutions for
next-generation Internet audio players. Cirrus Logic Inc. will introduce such
a part today (June 7), hoping to cash in on the nascent opportunity.
Consumer-electronics vendors traditionally have relied on fixed-function
digital signal processors and ASICs to solve design problems in portable
systems. But faced with the amorphousness of the still-emerging SDMI
spec and a host of other uncertainties, many are concluding that the
general-purpose-processor approach may no longer be overkill.
"They are relying on our expertise to find the right solution that would leave
them enough 'breathing space' to make their Internet music players
SDMI-compliant," said Joe Maurin, director of business development at
Cirrus Logic's Embedded Processor Division (Austin, Texas). SDMI-aware
Internet audio players are due out this Christmas.
Further, consumer companies have recognized that using a general-purpose
microprocessor with horsepower equivalent to an Intel 100-MHz 486 CPU
could eventually allow them to remove the PC from the Internet-music
equation.
The MP3 players available on the market today are positioned as PC
companion pieces, rather than standalone consumer devices. The portable
players let consumers decode downloaded Internet music and carry it with
them, but the heavy-duty processing tasks of Internet connection,
download and copy-protection-related decryption are today presumed to be
the PC's job.
Cirrus' Maurin noted that MP3-player manufacturers are divided into "a
PC-peripheral manufacturing camp and a CE [consumer electronics] camp."
The latter group, he said, is angling "to get the PC out of the loop" via
portable devices that would download music files, decipher copy-protection
schemes and decode music formats themselves.
How soon such appliances could be realized is anybody's guess. But even
Creative Labs, traditionally known as a PC peripherals vendor, considers
standalone, work-alone players the wave of the future. "I believe the players
will become less dependent on the PCs in the long run," said Hock Leow,
vice president of the multimedia division at Creative Labs. "One day, the
consumer [will be able to] 'jack' his or her unit at a kiosk and download
songs."
Leow envisions installations of such kiosks at "the neighborhood music
store or the ATM.
"These devices will be Internet Protocol-aware," he said. "With the 3G
[third-generation digital cellular] phones coming in the near future, they
could also connect to 3G phones and download music wirelessly."
'Content in any format'
For its part, the Secure Digital Music Initiative seeks to enable the
SDMI-compliant portable devices due for launch for the year-end holiday
season "to accept any content in any format the manufacturer allows,"
according to a recent statement released by Leonard Chiariglione, SDMI
executive director.
With formats up in the air, silicon programmability has become a top
priority for many system OEMs. Chip sets must prove themselves able to
handle a variety of storage devices, port connections and LCD quality
levels. That may mean a shift away from the approach taken for the current
crop of MP3 players, most of which are based on an ASIC chip set
developed by Micronas Intermetall (Freiburg, Germany).
"The most important features [OEMs look for] are programmability, tools
support, multiple codec support, low power, easy interface and excellent
system power management," said Creative's Leow.
Heeding that call, Cirrus Logic today will announce a solution based on its
embedded ARM720T processor technology.
Such DSP companies as Texas Instruments Inc. and Zoran Corp. have
recently tipped plans to enter the Internet-audio market with DSP-based
solutions. But Maurin said Cirrus believes that "when it comes to fulfilling
OEMs' diverse needs for handling different algorithms and interfaces, the
[fixed-function] DSP has limitations."
He added that "the combination of ARM's processing power, the chip's
ultralow-power feature and our expertise in integrating interface
components for such peripherals as LCDs and flash cards allows system
OEMs to efficiently design a flexible player and add differentiation."
Cirrus claims its chip, the EP7209, can replace three to five ICs used in
current MP3 players. Those devices would include a fixed-function DSP,
an external 8- or 16-bit microcontroller, and programmable logic devices for
storage, display and parallel ports.
The EP7209 integrates such peripherals as an LCD display controller, an
audio D/A converter interface and a flash-memory interface. Cirrus claims
the chip achieves extremely low power consumption by using a
combination of dynamically adjustable core clock frequencies and
low-power states that kick in during periods of inactivity.
For example, Maurin said, the EP7209 consumes less than 110 mW when
decompressing MP3 files with sample rates above 24 kHz. At sampling
frequencies below 24 kHz, power consumption falls to 80 mW; for sample
rates below 12 kHz, power consumption is 60 mW. The
power-management scheme should allow an Internet music player to run
music off its flash device for at least 12 hours on a single AA battery,
according to the Cirrus executive.
It is no coincidence that Cirrus' new device features an elaborate
power-management system and integrates interfaces for various peripherals,
since the EP7209 was designed initially for such handheld platforms as
Psion and Windows CE. "We have retasked the chip to decode music, since
we began to receive a lot of demand from the Far East to come up with a
silicon solution for Internet music players," said Maurin.
In tandem with the EP7209, Cirrus is launching the EP7211, similarly based
on the ARM720T. The 7211 is a system-on-chip design for handheld
devices supporting both Windows CE and Epoc 32.
Maurin cited growing interest among CE vendors to marry handheld devices
with Internet music players. He said his company will spin a follow-on chip
to serve that purpose within a few months.
The EP7209 accommodates both MP3 and Microsoft Corp.'s MS Audio
decompression algorithms in object code. Maurin said the flexible on-board
RISC processor and the availability of efficient C compilers and other
software-development tools ensure that a wide range of
audio-decompression algorithms can easily be ported to and run on the chip.
While more than half of the EP7209's available processing power is devoted
to the decompression of audio algorithms and copy-protection schemes, the
chip, operating at 74 MHz, still can devote 25 MHz to features that will let
OEMs differentiate their products from the competition, Maurin added.
Rather then dictate system implementations, SDMI is "specifying boundary
conditions" for a copy-protection system, Maurin noted. Although the
technology for a copy-protection mechanism, or trigger, is the subject of a
call for proposals that is still pending, Maurin said his company is confident
that the EP7209 will meet requirements.
For example, the industry group may decide to adopt a copy-protection
mechanism that would force portable devices to unlock keys continually,
rather than unlock keys only at the beginning of a download. But Cirrus'
"estimation is that this job would take no more than 10 MHz," Maurin said.
Cirrus' first implementation required 90 MHz for MP3 decode, but the
company hired a specialist whom Maurin called "the best coder of ARM" to
optimize the chip to enable MP3 decoding within less than 40 MHz of the
ARM's processing power. Even with the 10 MHz that would be required for
continually unlocking copy-protected files, the Cirrus chip is left with 25
MHz "to spare," he said.
Agnostic approaches
Most Internet-music player manufacturers agree that next-generation
devices will have to handle multiple audio-compression schemes. "In general
terms, we will definitely want our next player to play more than MP3," said
Creative Labs' Leow.
Bob Nelson, marketing manager at the RioPort division of Diamond
Multimedia, echoed that sentiment. "If multiple algorithms become popular
among consumers, it would be in our best interests to support as many as
possible," he said.
Maurin said Cirrus' OEM customers "are asking us to look into Real Audio's
G2, AAC [MPEG-2 Advanced Audio Coding] and AT&T's a2b" in addition
to MP3.
Peripherals choices are also diverging. Diamond's Nelson said his
company's top priority is speed. "Customers want to spend as little time as
possible moving files from their hard drive to a portable player. Therefore,
faster buses, like USB, are preferred," he said.
But Creative's Leow observed that parallel ports "are more universal, though
the speed is not the greatest." Thus, he said, "it is a convenience to offer
this to the installed PC base. "He further believes that "over time, 1394 will
be the interface of choice."
As for storage, system OEMs are looking at on-board flash, flash cards,
IBM's microdrives and recordable CD drives.
Creative's Leow sees two storage preferences varying by player category.
"For the ultra-portable device or wearable device, skip-free music playback
is essential. For these devices, flash memory is the way to go. Any
electromechanical devices will be subject to skipping during playback," he
said. "For the portable but not wearable players, the microdrive will start to
play an important role."
Cirrus' Maurin said some Asian vendors may opt for the recordable CD
drive, since "in some music stores in Hong Kong and Taiwan, customers
are allowed to download eight hours of music into recordable CD drives."
On the display front, companies are at odds over whether cost or
performance will rule the day. Maurin sees display-performance demands
rising in tandem with storage capacity. Cirrus' EP7209 comes with an LCD
controller, which interfaces directly to a single-scan monochrome LCD
panel. Panel width is programmable from 32 to 128 pixels and panel length
to 64 pixels.
Diamond's Nelson believes "a display with enough characters to show
detailed track information would be ideal."
But Creative's Leow argued that since "music is to be heard . . . hitting a
cost target is more important" than designing for maximum display
performance. |
