DESCRIPTION
The PDI1394L21, Philips Semiconductors Full Duplex 1394 Audio/Video (AV) Link Layer Controller, is an IEEE 1394–1995 compliant link layer controller featuring 2 embedded AV layer interfaces. The AV layers are designed to pack and un-pack application data packets for transmission over the IEEE 1394 bus using isochronous data transfers. Because of its full duplex architecture, the PDI1394L21 is capable of receiving and transmitting isochronous data during the same bus cycle. Two 8 bit AV ports, each with its own buffer (FIFO), receive and output isochronous data for transmission and reception of bus packets. Each port can be configured to receive or transmit, however, the other port always performs the opposite function. Half duplex operation is also permitted
The application data is packetized according to the IEC 61883 International Standard of Interface for Consumer Electronic Audio/Video Equipment. Both AV layer interfaces are byte-wide ports capable of accommodating various MPEG–2 and DVC codecs. An 80C51 compatible byte-wide host interface is provided for internal register configuration as well as performing asynchronous data transfers.

FEATURES
• IEEE 1394–1995 Standard Link Layer Controller
• Hardware Support for the IEC61883 International Standard of Digital Interface for Consumer Electronics
• Interface to any IEEE 1394–1995 Physical Layer Interface
• 5V Tolerant I/Os
• Single 3.3V supply voltage
• Full-duplex isochronous operation
• Operates with 400/200/100 Mbps physical layer devices
• Dual 4K Byte FIFOs for isochronous data
• Supports single capacitor isolation mode and IEEE 1394–1995, Annex J. isolation
• 4-field deep SYT buffer added to enhance real-time isochronous synchronization using the AVFSYNC pin
• Generates its own AV port clocks under software control. Select one of three frequencies: 24.576, 12.288, or 6.144 MHz