User Guide

Figure 39 WLAN block diagram

lrda interface

IrDA specifies a low-cost, reliable, fully digital peer-to-peer data link between IrDA units at data rates to

115.2k bits/s. The link is based on the serial transmission of data as pulses of infrared light at the wave length

of 870 nm and angles of +-15 degrees at the range 0 - 50 to 100 cm. Because these restrictions and the optical

nature of the link, the transmission is not omnidirectional but focused, and only reaches a peer at a limited

line-of-sight distance from the transmitter. Therefore, the transmission does not disturb any other units in

the neighbourhood.

The IR interface is implemented into the application processor. The processor block uses the UART3 circuit

to communicate with a standard IrDA transceiver. The IR transceiver module complies with the IrDA

specification version 1.4. The data rates are in the range of 9600 bit/s to 115200 bits/s.

The IR interface in the application processor and the IR transceiver module use the I/O voltage 1.8 V on the

Rx (processor receive), Tx (processor send), and SD (IR module shutdown) pins. The IR transmission is powered

from the phone battery VBAT (nominal 3.7 V) through a load resistor.

IR communication is half-duplex, meaning that the IR receiver sees its own transmission, and the IR interface

is either transmitting or receiving, but not both at the same time. IrDa modules consume current when the

IR detector is active.

RA-6

System Module

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