Zilog EZ80F916 - Manual (Page 30)

eZ80F91 Modular Development Kit
User Manual
UM017010-0112 eZ80F91 Module Operational Description
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Another signal that is used in the eZ80F91 Module’s IrDA system is
Shut_Down (SD). The SD pin is connected to PD2 on the eZ80F91 Mod-
ule. The IrDA control software on the user’s wireless device must enable
this pin to wake the IrDA transceiver. The SD pin must be set Low to
enable the IrDA transceiver. On eZ80F91 Module, a two-input OR gate is
used to allow an external pin to shut down the IrDA transceiver. Both pins
must be set Low to enable this function.
The eZ80F91 Module features an Infrared Encoder/Decoder register that
configures the IrDA function. This register is located at address
0BFh in
the internal I/O register map.
The Infrared Encoder/Decoder register contains three control bits:
Bit 0. Enables or disables the IrDA encoder/decoder block.
Bit 1. If set, this bit enables received data to pass into the UART0 Receive
FIFO data buffer.
Bit 2. A test function that provides a loopback sequence from the TxD pin
to the RxD input.
Bit 1, the Receive Enable bit, is used to block data from filling up the
Receive FIFO when the eZ80F91 Module is transmitting data. Because
air is the transmission medium that the the IrDA signal passes through,
the transmitted data can also be received; the Receive Enable bit prevents
this data from being received. After the eZ80F91 Module completes
transmitting, this bit is changed to allow for incoming messages.
The code that follows provides an example of how this function is
enabled on the eZ80F91 Module.