Imaging competitors choose divergent paths to a nebulous destination
By Brian Dipert -- EDN, March 18, 2004
At first glance, Texas Instruments’ $15 (100,000) TMS320DM320, with its prominent dual ARM9 and C54x DSP cores inside, may look identical to the earlier generation $13 DM310. However, whereas the DM310 used a 144-MHz ARM925, the DM320 uses a 160-MHz ARM926EJ-S, along with a sequencer. In the DM320, TI also includes the earlier $11 DM270’s memory-traffic controller, supporting chips, modules, and host CPUs with both multiplexed—that is, SDRAM—and nonmultiplexed buses, versus the DM310’s less comprehensive SDRAM-only controller.
The DM320 enhances the capabilities and speed of its DM310 predecessor’s eight-MAC (multiply-accumulate) imaging coprocessor and preview engine, and it provides a glueless interface to LCDs. Other additions on the DM320 include a hardwired DCT (direct-cosine-transform) accelerator block, On-The-Go support in the 12-Mbps USB controller, and various chip-to-chip interfaces. The anticipated performance results of all this fine-tuning speak for themselves (Table 1). TI forecasts that, with first engineering samples now in hand and undergoing debugging, it will be able to ramp the DM320 into volume production by the fourth quarter; the fact that the DM320 shares its precursors’ 0.13-micron process will assist in this ramp-up. Beta development software is now available, and TI plans a general development-tool rollout for early next quarter.
The incremental hardware acceleration TI has added to successive processor generations draws the company ever-closer to the hard-wired approach that competitors such as NuCore Technology have long espoused (see “Imaging chip set speedily delivers the bits,” EDN, Aug 3, 2000, pg 28 ). However, aside from the opponents’ common use of an ARM9 processor core, significant implementation differences remain. TI, after all, leverages a DSP that has general-purpose roots, whereas NuCore relies on imaging-optimized circuitry. Kyocera (www.kyocera.com) is now shipping 3 million- and 5 million-pixel cameras that contain NuCore chip sets; the cameras can capture near-infinite-length bursts of 3.5 and 3 frames/sec, respectively. (Nonvolatile storage capacity places the only limitations on the length of the bursts.)
According to NuCore, if it weren’t for front-end sensor and back-end flash-memory performance bottlenecks, the 3 million-pixel camera’s sustained bursts could hit 5 frames/sec.
Aside from NuCore’s imaging-centric digital-processing approach, the other reason for the architecture’s speed is the inclusion of a separate analog-based chip for white balance, black-level calibration, and other sensor-optimization functions instead of a reliance on DSP cycles to implement those functions. The two-chip combo of NDX-1260 analog and SiP-1270 digital processors for CCD-based systems costs $16 (1 million); if your design employs a CMOS sensor, you need to purchase only the $13.50 SiP-1270. The two companies’ chip announcements come on the heels of both near-term euphoria and long-term uncertainty about the viability of the stand-alone-camera market. Camera-inclusive cell phones on the low end and still-image-enhanced camcorders encroaching from above may, by the decade’s end, squeeze out digital still cameras, even with video enhancements.
Texas Instruments, 1-972-995-2011, www.ti.com.
NuCore Technology, 1-408-907-7100, www.nucoretech.com.
