AR2

2 Channels, ARINC 568/579 Communications

The AR2 module provides an ARINC 568/579 communications interface with 2 channels. Channel 1 is Rx and Tx for ARINC 568 and channel 2 is programmable as either Rx or Tx for ARINC 579. This module only provides an interface and data management. Any specific protocol handling must be programmed by the user in the application layer.

ARINC 568 is an equipment characteristic for Distance Measurement Equipment (DME). DMEs allow aircraft to calculate their position by sending signals to ground based radio beacons and uses the time between the response minus a preset delay to calculate the distance of the aircraft from the beacon. ARINC 568 is a six-wire system involving 3 pairs of wires paired as "clock", "word sync" and "data" respectively. The word length is 32 bits. The first eight bits are the address or label and the last 24 bits are transferred as data.

ARINC 579 is an equipment characteristic for a VHF Omnidirectional Radio range (VOR) short range navigation system. VORs enable an aircraft with a receiving unit to determine its position by receiving radio signals transmitted by a network of ground fixed radio beacons. ARINC 579 is programmable as either a transmitter or a receiver. When programmed as a receiver, the module will wait for 4 null states before processing a message. Once the message is processed, the module will return to waiting for null states.

For the AR2 module, the ARINC 568 and 579 standards are implemented on separate channels. Channel 1 is ARINC 568 and channel 2 is ARINC 579. For both ARINC 568 and 579, when messages are received, the FIFO can be programmed to not accept any additional data when full or to overwrite the oldest data when full. These modes are called bounded mode or circular mode (default) respectively. While transmitting, both ARINC standards can either send data immediately or buffer the data while waiting for a trigger. When the transmit FIFO is full, it can be programmed for either bounded mode or circular mode as well.

Features

• Receive/Transmit mode programmable channel (ARINC-579)
• Separate Receive and Transmit channel (ARINC-568)
• 11 kHz transmission rate
• Programmable gap times
• Transmit: 1024-word FIFO per channel
• Receive: 1024-word FIFO per channel
• Selectable hardware parity generation/checking
• Receive time stamping Continuous BIT
• Loop-back test
• Tri-state outputs
• High and Low Speed Slew Rate outputs