EM78P257
OTP ROM
4.12 INFRARED REMOTE APPLICATION MODE
1. Overview & Features
Overview:
EM78P257A/B is designed for use in universal infrared remote commander applications. Fig.26 shows the
hardware modulator of EM78P257A/B. It can generate programmable pulse trains for driving an infrared LED.
Features:
• Power saving : Idle and Stop modes are provided
• Hardware Modulator providing pulse bursts , with:
-- programmable duty factor for each pulse
-- programmable number of pulse
• Watchdog timer to keep the transmitter from being locked or malfunction
• On-chip oscillator: 455kHz to 24MHz
High-time
end
IR OUT
start
Elapse time by software
Low-time
interrupt
pulse #3
pulse #2
pulse #1
Low-time = 2 (Low-time register =) 2High-time = 4(High-time register = 4) number of pulse = 3
Fig. 26 Example Pulse Train Output of IR OUT Pin
This specification is subject to change without prior notice.
59
07.27.2004 (V1.4)
ELAN [ ELAN MICROELECTRONICS CORP ]
