Adding Interfaces To PCI Embedded Designs

Alain Sorin explains how PCI companion chip technology efficiently brings common interfaces to new and existing multimedia and networking designs.

A growing number of applications demand storage and connectivity for digital content. This applies to personal video recorders (PVRs), set top boxes (STBs), information appliances, home gateways, simple routers and routers with network shared storage and/or printers. As a result of rising volumes, the cost of storage media such as small hard disk drives (HDD) and flash memory cards continues to fall, while interfaces such as USB and IDE are becoming de facto standards for device connectivity and storage.

Engineers are under pressure to find ways of integrating the many common interfaces for connection to peripherals including imaging devices, scanners, printers, fixed and removable storage media such as hard disks, and CompactFlash cards. This integration needs to be achieved keeping cost, design time and component count to a minimum in both new and existing designs.

THE COMPANION CHIP
Toshiba has developed a multifunction IC that allows engineers to add several interfaces quickly and simply to the latest and extant designs. This chip, the TC86C001FG (also known as the GOKU-S), sits alongside the RISC processors normally used in embedded multimedia applications and other designs where the storage, management and communication of digital content are key (see Figure 1). These include PCs, keyboards, mice, memory card readers, digital cameras and WiFi access points as well as those already mentioned.

As the diagram shows, the chip has six industry standard interfaces: a PCI interface; an ATA/ATAPI host controller, two USB host controllers; a USB device controller; an I2C interface; and a serial UART.

The IDE bus master (ATA/ATAPI) controller provides the common interface needed for connection of HDD, CD and DVD drives or memory cards, such as CompactFlash, and a single channel for up to two devices in a master/slave configuration. The controller supports Ultra DMA modes from 0 to 4, and operates at speeds up to 66.67Mbp/s in Ultra DMA Mode 4 as well as PIO modes.

The USB host controller is compatible with USB specification version 1.1 and has two USB ports that support device bandwidths of 12Mbp/s (USB 2.0 full speed) and 1.5Mbp/s (low speed). An over-current detector protects the USB bus from abnormal current overload. The additional integrated USB device controller, which is also USB 1.1-compliant, offers USB 2.0 full speed USB data transfer and supports control transfer, bulk transfer and interrupt transfer.

The general purpose communication controller built into the TC86C001FG gives the engineer a single-channel master/slave I2C bus, a full duplex UART, and a maximum of five GPIO pins. The bus reduces the number of pins and wires on the PCB and this interface enables a variety of IC peripherals for video and audio applications, as well as EPROM, to be added easily.

The TC86C001FG's integrated PCI interface with its arbiter is specifically for engineers needing to upgrade existing applications. This 3.3V, 32bit, 33MHz interface is compliant with revision 2.2 of the PCI Local Bus specification, and enables connection to PCI-based ASSPs. In other words, this interface allows the TC86C001FG to be integrated into any application that already has PCI connectivity. As PCI capability is now common on RISC CPUs from all large semiconductor manufacturers, the Toshiba companion chip can be used to upgrade or migrate an existing design with the bare minimum of circuit redesign. For example, the TC86C001FG could be added to a router to provide USB connectivity/spooling storage for a printer or file server. Or it could bring PVR/card reader functionality to an STB application through the addition of an ATA HDD or CompactFlash card.

REFERENCE DESIGN
Toshiba has developed a number of reference platforms to demonstrate the functionality of the TC86C001FG IC using its family of 64bit TX System RISC processors. The AVM49R platform is a good example of these reference designs. It was created to support the rapid development of PVR, cheap multimedia gateways, IP STB and videophones, home media servers and clients. It was developed in collaboration with VWEB Corporation and MontaVista Software and supports real-time MPEG2/4 simultaneous encoding and decoding for full D1 PAL/NTSC resolution (TV), and high quality audio and video streaming. An extra PCI slot can accommodate other extensions such as wireless module (802.11a/b/g) or connection to a firewire.

Figure 2 is a schematic of the AVM49R platform system configuration which combines a Toshiba TX4938 MIPS-based RISC processor, the TC86C001FG companion chip and the VWEB VW2010 MPEG-1/2/4 encoder/decoder chip.

The RISC processor shown is Toshiba's 64bit TMPR4938 360 MIPS device running at 300MHz with: two 10/100Mbit Ethernet MACs; an integrated memory controller (SDRAM, NOR and NAND flash); a 66MHz, 32bit, Rev 2.2 PCI controller; UARTs; a timer; an SPI; and an AC97 audio /modem Codec. The built-in boot ROM means that NAND flash memories can be used instead of more expensive NOR flash. The platform's internal/external 64bit bus and instruction and data caches (32k/32k) with four-way set association provide the necessary bandwidth for all embedded peripherals.

The VWEB VW2010 video codec provides video quality combined with efficient compression for storage and bandwidth related applications. VWEB's MPEG2 to MPEG4 transcoding and transrating technologies enable end-to-end video distribution across networks.

The AVM49R reference platform runs under MontaVista Linux operating system. The MontaVista Linux support package offers all of the necessary drivers used in the applications targeted by the reference design.

DEVELOPMENT SUPPORT
A PCI based development board (RBHPE4300 — see Figure 3) is available to help designers implement the TC86C001FG in their applications. It includes the companion chip itself along with all the necessary connectors (IDE, two USB host, one USB device, JTAG, UART, PIO) and cables.

Toshiba has produced a variety of development boards that will speed the design and testing of digital consumer electronics and networking applications based on the company's TX RISC family of 64bit processors as well as dedicated reference designs such as the AVM49R. The TC86C001FG can be plugged directly into the single PCI slot of the development boards which include RBHMA4300 for TX4925, RBHMA4400 for TX4937 and RBHMA4500 for the TX4938.

Developers using Toshiba's processors have access to a variety of real-time operating system (RTOS) supported by the TX49 processor family as well as the hardware. RTOS options include VxWorks from Wind River Systems, ThreadX and Integrity from Green Hills Software, OSEK from Vector Informatik and MontaVista's Linux whose Linux Support Package (LSP) provides the commonly used device drivers including USB, PCI and ATA/IDE under GPL. MontaVista offers a free download option via its preview kits for the Toshiba TX49 reference board LSPs. In terms of application development, the Toshiba TX49 reference boards can be used with third party tools including the Multi2000 development tool chain from Green Hills Software, RedHat's GNUPro tool chain, as well as EJTAG emulator and debugger tools from Yokogawa Digital Computer and Green Hills Software.

Thanks to their performance, various middleware like MP3 encoder/decoder can be executed by software on Toshiba 64bit processors, while the companion chip provides content storage and retrieval on HDD or CompactFlash card.

Finally, Toshiba has developed a number of application notes that are dedicated to users implementing applications based on the TC86C001FG.

The TC86C001FG GOKU-S embedded companion chip IC provides a single-chip solution for designers looking to add common interfaces to new and existing embedded designs.

Unlike many large companion chips developed for the PC market, GOKU-S includes a limited set of peripherals that are necessary for most modern embedded designs within a small LQFP 144 pins package. Originally developed for Toshiba's own TX49 64-bit RISC processors, the TC86C001FG can also be used alongside processors from other manufacturers thanks to the integration of a PCI 2.2-compliant bus interface. As a result, a variety of digital consumer and networking applications can use the companion chip, while reference designs, development boards and third party software and tools will help speed prototyping and implementation.

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