Fast Infrared Communication Port

11

The Fast Infrared Communications Port (FICP) for the PXA255 processor operates at half-duplex and provides direct connection to commercially available Infrared Data Association (IrDA) compliant LED transceivers. The FICP is based on the 4-Mbps IrDA standard and uses four- position pulse modulation (4PPM) and a specialized serial packet protocol developed for IrDA transmission. To support the standard, the FICP has:

A bit encoder/decoder,

A serial-to-parallel data engine

A transmit FIFO 128 entries deep and 8 bits wide

A receive FIFO 128 entries deep and 11 bits wide

The FICP shares GPIO pins for transmit and receive data with the Standard UART. Only one of the ports can be used at a time. To support a variety of IrDA transceivers, both the transmit and receive data pins can be individually configured to communicate using normal or active low data.

11.1Signal Description

The FICP signals are IRRXD and IRTXD. Table 11-1describes each signal’s function. Most IrDA transceivers also have enable and speed pins. Use GPIOs to enable the transceiver and select the speed. See Chapter 4, “System Integration Unit” for more information.

Table 11-1. FICP Signal Description

Signal Name

Input/Output

Description

 

 

 

IRRXD

Input

Receive pin for FICP

 

 

 

IRTXD

Output

Transmit pin for FICP

 

 

 

11.2FICP Operation

The FICP is disabled and does not have control of the port’s pins after a reset. Before software enables the FICP for high-speed operation, it must set the control registers to reflect the desired operating mode. After the control registers are set, software can either preload the FICP’s transmit FIFO with up to 128 bytes, or leave the FIFO empty and use the DMA to service it after the FICP is enabled. Once the FICP is enabled, transmit/receive data can be sent on the transmit and receive pins.

The transmit/receive data is modulated according to the 4PPM IrDA standard and converted to serial or parallel data. The modulation technique and the frame format are discussed in the sections that follow.

Intel® PXA255 Processor Developer’s Manual

11-1

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Intel PXA255 manual Ficp Operation, Ficp Signal Description