Z8F021ASH020SC datasheet(129/276 Pages) ZILOG

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PS022815-0206

Infrared Encoder/Decoder

Z8 Encore! XP® 4K Series

Product Specification

110

is passed to the Infrared Endec through the RXD pin, decoded by the Infrared Endec, and

passed to the UART. Communication is half-duplex, which means simultaneous data

transmission and reception is not allowed.

The baud rate is set by the UART’s Baud Rate Generator and supports IrDA standard baud

rates from 9600 baud to 115.2 Kbaud. Higher baud rates are possible, but do not meet

IrDA specifications. The UART must be enabled to use the Infrared Endec. The Infrared

Endec data rate is calculated using the following equation:

Transmitting IrDA Data

The data to be transmitted using the infrared transceiver is first sent to the UART. The

UART’s transmit signal (TXD) and baud rate clock are used by the IrDA to generate the

modulation signal (IR_TXD) that drives the infrared transceiver. Each UART/Infrared

data bit is 16 clocks wide. If the data to be transmitted is 1, the IR_TXD signal remains

low for the full 16 clock period. If the data to be transmitted is 0, the transmitter first out-

puts a 7 clock low period, followed by a 3 clock high pulse. Finally, a 6 clock low pulse is

output to complete the full 16 clock data period. Figure 17 illustrates IrDA data transmis-

sion. When the Infrared Endec is enabled, the UART’s TXD signal is internal to the Z8

Encore! XP® 4K Series products while the IR_TXD signal is output through the TXD pin.

Figure 17.Infrared Data Transmission

Infrared Data Rate (bits/s)

System Clock Frequency (Hz)

16 UART Baud Rate Divisor Value

----------------------------------------------------------------------------------------------

Baud Rate

IR_TXD

UART’s

16 clock

period

Start Bit = 0

Data Bit 0 = 1

Data Bit 1 = 0

Data Bit 2 = 1

Data Bit 3 = 1

7-clock

delay

3 clock

pulse

TXD

Clock

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