Z8F640x/Z8F480x/Z8F320x/Z8F240x/Z8F160x
Z8 Encore!®
96
Operation
When the Infrared Endec is enabled, the transmit data from the associated on-chip UART
is encoded as digital signals in accordance with the IrDA standard and output to the infra-
red transceiver via the TXD pin. Likewise, data received from the infrared transceiver is
passed to the Infrared Endec via the RXD pin, decoded by the Infrared Endec, and then
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:
System Clock Frequency (Hz)
16 × UART Baud Rate Divisor Value
----------------------------------------------------------------------------------------------
Infrared Data Rate (bits/s) =
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, a 3-clock high pulse is
output following a 7-clock low period. After the 3-clock high pulse, a 6-clock low pulse is
output to complete the full 16-clock data period. Figure 72 illustrates IrDA data transmis-
sion. When the Infrared Endec is enabled, the UART’s TXD signal is internal to the
Z8F640x family device while the IR_TXD signal is output through the TXD pin.
PS017610-0404
Infrared Encoder/Decoder
ZILOG [ ZILOG, INC. ]
