20 GENERAL-PURPOSE SERIAL INTERFACE (FSIO)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
20-19
Setting IrDA Interface
20.8.2
When performing infrared-ray communication, the following settings must be made before communication can be
started:
1. Setting input/output pins
2. Selecting the interface mode (IrDA interface function)
3. Setting the transfer mode
4. Setting the input clock
5. Setting the data format
6. Setting the receive FIFO level
7. Setting interrupts and DMA
8. Setting the input/output logic
The contents for items 1 through 6 have been explained in connection with the asynchronous interface. For details,
refer to Section 20.7, “Asynchronous Interface.” For details on item 7, refer to Section 20.9, “FSIO Interrupts and
DMA.”
Note: Before making these settings, always make sure the serial interface is inactive (TXEN/FSIO_CTL
x
register and RXEN/FSIO_CTL
x
register are both set to 0), as a change in settings during opera-
tion could cause a malfunction.
In addition, be sure to set the transfer mode in (3) and the following items after selecting the IrDA
interface function in (2).
Selecting the IrDA interface function
To use the IrDA interface function, select it using IRMD[1:0]/FSIO_IRDA
x
register and then set the 8-bit (or
7-bit) asynchronous mode as the transfer mode.
8.2.1 Setting of IrDA Interface
Table 20.
IRMD[1:0]
Interface mode
0x3
Setting prohibited (reserved)
0x2
IrDA 1.0 interface
0x1
Setting prohibited (reserved)
0x0
Normal interface
(Default: 0x0)
Setting the input/output logic
When using the IrDA interface, the logic of the input/output signals of the RZI modulator circuit can be
changed in accordance with the infrared-ray communication module or the circuit connected externally to the
chip. The logic of the internal serial interface is “active-low.” If the input/output signals are active-high, the
logic of these signals must be inverted before they can be used. The input SIN
x
and output SOUT
x
logic can be
set individually through the use of IRRL/FSIO_IRDA
x
register and IRTL/FSIO_IRDA
x
register, respectively.
The logic of the input/output signal is inverted by writing 1 to IRRL/IRTL. Logic is not inverted if the bit is set
to 0.