Irda Interface - Epson S1C17704 Technical Manual

18.8 IrDA Interface

The UART module contains an RZI modulator/demodulator, allowing an infrared-ray communication circuit to be
configured based on IrDA 1.0 simply by adding an external circuit.
The transmit data output from the shift register of the UART is input to the modulator to convert the low pulse
width into 3/16 sclk cycles before it is output from the SOUT pin.
Modulator input (shift register output)
Modulator output (SOUT)
Modulator input (shift register output)
Modulator output (SOUT)
The received IrDA signal is input to the demodulator to convert the low pulse width into 16 sclk cycles before input
to the shift register for receiving. To detect low pulses input to the demodulator (minimum pulse width = 1.41 µs at
115200 bps), the demodulator uses a pulse detection clock selected from the prescaler output clocks separately with
the transfer clock sclk.
Demodulator input (SIN)
Demodulator output (shift register input)
Demodulator input (SIN)
Demodulator output (shift register input)
Enabling the IrDA mode
To use the IrDA interface function, set the IRMD bit (D0/UART_EXP register) to 1. This enables the RZI
modulator/demodulator.
∗ IRMD: IrDA Mode Select Bit in the UART Expansion (UART_EXP) Register (D0/0x4105)
Note: This setting must be performed before setting other UART conditions.
S1C17704 TECHNICAL MANUAL
S1 D0 D1
sclk
1 2 3
Figure 18.8.1 Transmit Signal Waveform
S1 D0 D1
sclk
1 2 3 4
irclk
2 × irclk or more
Figure 18.8.2 Receive Signal Waveform
EPSON
(S1: Start bit, S2 & S3: Stop bits, P: Parity bit)
D2 D3 D4 D5 D6
8 9 10 11 16
3 × sclk
(S1: Start bit, S2 & S3: Stop bits, P: Parity bit)
D2 D3 D4 D5 D6
16 × sclk
18 UART
D7 P S2 S3
D7 P S2 S3
16
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