HomeThe Bluewater BlogCortex-R4 in Blu-Ray

I don't have a Blu-Ray player yet. People tell me the best option at the moment is to get a Playstation 3, but I don't have a TV to do it justice, so have held off. I need the current TV to break first (accidentally, of course). Having said that I notice that Blu-Ray discs are starting to make an appearance at the video store, so perhaps that will push me over the edge. But at the moment, Blu-Ray is an 'early' technology, yet to hit the massive volumes of the consumer mainstream. The Cortex-R4 is in a similar position in terms of its visibility in the microcontroller market. While there are at least a dozen licensees, I believe only TI has announced a part based around it - presumably TI had a hand in the conception of the device. The Cortex-R4 is living up to its 'deeply embedded' name. Some of the features of the Cortex-R4 are:

  • 8-stage pipeline (partly superscalar)
  • Performance 400MHz (although 600MHz was subsequently announced)
  • Resulting 600 DMIPS at 400MHz, and presumably 900 DMIPS at 600MHz
  • Architecture ARMv7, including very low interrupt latency features
  • Floating point unit (FPU)
  • Branch prediction and prefetch
  • Tightly coupled memory (TCM) aka internal single cycle SRAM, as well as caches
  • Memory protection unit (MPU)
  • Advanced profiling support, hardware divide, CoreSight debug and ECC memory support
The Cortex-R4 is ridiculously configurable, for example allowing three different MPU options, 3 TCM port options (with different sizes as well), selectable number of breakpoints and watchpoints and floating point or not. One can only imagine what sort of unit volumes / cost pressures might drive such extreme configurability. Not content with a single core, TI's TMS570 range includes two cores running together, although the second can be a Cortex-M3 instead. This is a serious amount of processing power for automotive applications. But ARM has aimed the chip at more than just the automotive market. Disk drives, both magnetic and optical; ink jet and laser printers, and even 3G modems. Which brings us back to Blu-Ray. Broadcom has announced that it has selected Cortex-R4 for its next-generation of Blu-Ray player chips. One point noted in the PR is that the Cortex-R4 allows the TCMs to be powered while the CPU itself is stopped. It isn't clear what this is used for - perhaps to allow data transfer to happen under DMA while processing is suspended. Broadcom's new chip is presumably a replacement for the MIPS-based BCM7440 single chip solution. The level of technology in these devices is a wonder to behold. Let's hope ARM announces a Japanese licensee this year, and perhaps someone in the disk drive market. In the meantime, I predict that the first company to put this new Cortex-R4 part into a Blu-Ray player will at last drag me into the high definition world.