Zilog EZ80F91 - Manual (Page 54)

eZ80F91 Development Kit
User Manual
UM014220-0508 eZ80F91 Module
49
condition. The RESET pin on the I/O connector reflects the status of the
RESET line. It is a bidirectional pin for resetting external peripheral
components or for resetting the eZ80F91 Development Kit with a low-
impedance output (for example, a 100
Ω
push button).
IrDA Transceiver
An onboard IrDA transceiver (ZHX1810) is connected to PD0 (TX), PD1
(RX), and PD2 (Shutdown, IR_SD). The IrDA transceiver is of the LED
type 870 nm Class 1.
The IrDA transceiver is accessible via the IrDA controller attached to
UART0 on the eZ80F91 device. While using the IrDA transceiver, you
must disable the console port on the eZ80Acclaim!
®
Development Kit.
See Table 6 on page 20.
To use the UART0 as a console or to save power, the transceiver can be
disabled by the software or by an off-board signal when using the proper
jumper selection. The transceiver is disabled by setting PD2 (IR_SD)
High or by pulling the DIS_IRDA pin on the I/O connector Low. The
shutdown feature is used for power savings. To enable the IrDA trans-
ceiver, DIS_IRDA is left floating and PD2 is pulled Low.
The RxD and TxD signals on the transceiver perform the same functions
as a standard RS-232 port. However, these signals are processed as IrDA
3/16 coding pulses (sometimes called IrDA encoder/decoder pulses).
When the IrDA function is enabled, the final output to the RxD and TxD
pins are routed through the 3/16 pulse generator.
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 wireless device must enable this
pin to wake the IrDA transceiver. The SD pin must be set Low to enable
the IrDA transceiver. On the 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.