Christopher Hallinan - Embedded Linux Primer - A Practical, Real-World Approach

The MIPS Technology website lists 73 licensees who are currently engaged in manufacturing products using MIPS processor cores. Some of these companies are household names, as with Sony, Texas Instruments, Cisco's Scientific Atlanta (a leading manufacturer of cable TV set-top boxes), Motorola, and others. Certainly, one of the largest and most successful of these is Broadcom Corporation.

Broadcom is a leading supplier of SOC solutions for markets such as cable TV set-top boxes, cable modems, HDTV, wireless networks, Gigabit Ethernet, and Voice over IP (VoIP). Broadcom's SOCs have been very popular in these markets. We mentioned earlier that you likely have Linux in your home even if you don't know it. Chances are, if you do, it is running on a Broadcom MIPS-based SOC.

In 2000, Broadcom acquired SiByte Inc., which resulted in the communications processor product lineup the company is currently marketing. These processors currently ship in single-core, dual-core, and quad-core configurations. The company still refers to them as SiByte processors.

The single-core SiByte processors include the BCM1122 and BCM1125H. They are both based on the MIPS64 core and operate at clock speeds at 400-900MHz. They include on-chip peripheral controllers such as DDR SDRAM controller, 10/100Mbps Ethernet, and PCI host controller. Both include SMBus serial configuration interface, PCMCIA, and two UARTs for serial port connections. The BCM1125H includes a triple-speed 10/100/1000Mbps Ethernet controller. One of the more striking features of these processors is their power dissipation. Both feature a 4W operating budget at 400MHz operation.

The dual-core SiByte processors include the BCM1250, BCM1255, and BCM1280. Also based on the MIPS64 core, these processors operate at clock rates from 600MHz (BCM1250) to as high as 1.2GHz (BCM1255 and BCM1280). These dual-core chips include integrated peripheral controllers such as DDR SDRAM controllers, various combinations of Gigabit Ethernet controllers, 64-bit PCI-X interfaces, and SMBus, PCMCIA, and multiple UART interfaces. Like their single-core cousins, these dual-core implementations also feature low power dissipation. For example, the BCM1255 features a 13W power budget at 1GHz operation.

The quad-core SiByte processors include the BCM1455 and BCM1480 communications processors. As with the other SiByte processors, these are based on the MIPS64 core. The cores can be run from 800MHz to 1.2GHz. These SOCs include integrated DDR SDRAM controllers, four separate Gigabit Ethernet MAC controllers, and 64-bit PCI-X host controllers, and also contain SMBus, PCMCIA, and four serial UARTs.

Table 3-7 summarizes select Broadcom SiByte processors.

Table 3-7. Broadcom Select SiByte Processor Highlights

Advanced Micro Devices also plays a significant role in the embedded MIPS controller market. The company's 2002 acquisition of Alchemy Semiconductor garnered several popular single-chip integrated SOCs based on the MIPS32 core and architecture. The Alchemy line from AMD is based on the popular MIPS32 core. All feature relatively low power dissipation and a high level of onboard system integration.

The Au1000 and Au1100 operate at clock rates of 266-500MHz. Both feature onboard SDRAM controllers and separate bus controllers for attachment to external devices such as Flash and PCMCIA. Table 3-8 summarizes the current Alchemy product line.

Table 3-8. AMD Alchemy MIPS Highlights Summary

As we pointed out earlier, nearly 100 current MIPS licensees are shown on the MIPS Technologies licensees web page, at www.mips.com/content/Licensees/ProductCatalog/licensees. Unfortunately, it is not possible in the space provided here to cover them all. Start your search at the MIPS technologies website for a good cross-section of the MIPS processor vendors.

For example, ATI Technologies uses a MIPS core in its Xilleon set-top box family of chipsets. Cavium Network's Octeon family uses MIPS64 cores in a variety of multicore processor implementations. Integrated Device Technology, Inc., (IDT) has a family of integrated communications processors called Interprise, based on the MIPS architecture. PMC-Sierra, NEC, Toshiba, and others have integrated processors based on MIPS. All of these and more are well supported under Linux.

The ARM architecture has achieved a very large market share in the consumer electronics marketplace. Many popular and now ubiquitous products contain ARM cores. Some well-known examples include the Sony PlayStation Portable (PSP), Apple iPod Nano, [23] Reported by ARM to be the top-selling toy during the Christmas 2005 shopping season in the United States. Nintendo Game Boy Micro and DS, TomTom GO 300 GPS, and the Motorola E680i Mobile Phone, which features embedded Linux. Processors containing ARM cores power a majority of the world's digital cellular phones, according to the ARM Corporate Backgrounder at www.arm.com/miscPDFs/3822.pdf.

The ARM architecture is developed by ARM Holdings, plc and licensed to semiconductor manufacturers around the globe. Many of the world's leading semiconductor companies have licensed ARM technology and are currently shipping integrated processors based on one of the several ARM cores.