em78p468l ELAN Microelectronics Corp, em78p468l Datasheet - Page 47

• Manufacturer Part Number: em78p468l
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.5) 02.15.2007
(This specification is subject to change without further notice)
6.10 Infrared Remote Control Application/PWM Waveform Generate
This LSI can output infrared carrier in user-friendly or in PWM standard waveform. The IR
and PWM waveform generated functions include an 8-bit down count timer/counter,
high-pulse width timer, low-pulse width timer, and IR control register. The IR system block
diagram is shown in Fig. 6-20. The IROUT pin waveform is determined by IR control
register (RE), IOC90 (Counters 1 and 2 control register), IOCA0 (high-pulse width timer,
low-pulse width timer control register), IOCC0 (Counter 2 preset), IOCD0 (high-pulse width
timer preset register), and IOCE0 (low-pulse width timer preset register). Details on
Fcarrier, high-pulse time, and low pulse time are explained as follows :
If Counter 2 clock source is F
If the high-pulse width timer clock source is FT (this clock source can be set by IOCA1), then
If the low-pulse width timer clock source is FT (this clock source can be set by IOCA1);
Fm: main oscillator frequency Fs: sub-oscillator frequency
T
T
F
high
low
8 bit dow n c ounter
carrier
A uto-reload buf f er
Pre-s caler
pulse
Fs
Counter 2
pulse
(IOCC0)
(IOC91)
=
time
2
Fm
time
×
8
8
1 (
=
=
+
prescaler
prescaler
decimal
Pre-scaler
(IOC A 1)
Fcarrier
Fig. 6-20 IR/PWM System Block Diagram
HF
×
×
of
1 ( +
1 ( +
T
(this clock source can be set by IOC91), then
RE register
C
decimal
decimal
ounter
High-Pulse Width Timer
8 bit dow n counter
A uto-reload buf f er
LGP
(IOCD0)
of
2
of
H/W Modulator Circuit
IRE
8
8
8
F
preset
T
low
high
F
value
pulse
EM78P468N/EM78P468L
F
T
pulse
T
Low -Puls e Width Timer
8 bit dow n counter
A uto-reload buf f er
(
width
IOCC
width
8-Bit Microcontroller
( IOCE0)
Pre-s caler
(IOCA 1)
0
timer
8
8
8
))
timer
×
prescaler
value
value
IROUT pin
• 41
(
IOCE
(
IOCD
0
))
0
))