EM78P341N/342N/343N
8-Bit Microprocessor with OTP ROM
6.8 Infrared Remote Control Application/PWM Waveform Generation
6.8.1 Overview
This LSI can easily output infrared carrier or PWM standard waveform. As illustrated
below, the IR and PWM waveform generation function include an 8-bit down count
timer/counter, high-time, low-time, and IR control register. The IROUT pin waveform is
determined by IOCA0 (IR and TCCC scale control register), IOCB1 (high-time rate,
low-time rate control register), IOC81 (TCCC counter), IOCA1 (high-time register), and
IOC91 (low-time register).
FT:CLK(Fosc)
8 Bit counter
8-to-1 MUX
8 Bit counter
8-to-1 MUX
8 Bit counter
8-to-1 MUX
Scale
(IOCB1)
Scale
(IOCB1)
Scale
(IOCA0)
8
8
Auto-reload buffer
(High-time)(IOCA1)
Auto-reload buffer
(Low-time)(IOC91)
8bit binary
down counter
8bit binary
down counter
8
8
Fcarrier
8bit binary
down counter
H/W Modulator
8
Auto-reload buffer
(TCCC)(IOC81)
HF
Underflow Interrupt
HPWTIF
LPWTIF
LG
IR
IROUT
Fig. 6-12 IR/PWM System Block Diagram
NOTE
Details of the Fcarrier high time width and low time width are explained below:
Fcarrier =
FT/ 2 { [1+decimal TCCC Counter value (IOC81)] * TCCC
Scale(IOCA0) }
High time width = { [1+decimal high-time value (IOCA1)] * High time Scale(IOCB1) } /
FT
Low time width = { [1+decimal low-time value (IOC91)] * Low time Scale(IOCB1) } /
FT
Where FT is the system clock FT=Fosc/1(CLK=2)
FT=Fosc/2(CLK=4)
When an interrupt is generated by the High time down counter underflow (when
enabled), the next instruction will be fetched from Address 018 and 01BH (High time
and Low time respectively).
60 •
Product Specification (V1.0) 12.01.2006
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
