EM78468
8-BIT Microcontroller
Pre-scaler
(IOCA1)
High-Pulse Width Timer
(IOCD0)
Low -Pulse Width Timer
( IOCE0)
Fs Fm
8
8
Auto-reloadbuffer
Auto-reloadbuffer
Pre-scaler
(IOC A1)
8
8
Pre-scaler
(IOC91)
8 bit dow n counter
8
8 bit dow n counter
8
Fcarrier
8 bit dow n counter
H/W Modulator Circuit
IROUTpin
8
Auto-reloadbuffer
8
HF
LGP
IRE
REregister
Counter 2
(IOCC0)
Fm: main oscillator frequency; Fs: sub-oscillator frequency
Fig. 21 IR/PWM System Block Diagram
The IROUT output waveform is further explained in the following figures:
Fig. 22: LGP=0, HF=1, the IROUT waveform can modulate Fcarrier waveform when in
low-pulse width time.
Fig. 23: LGP=0, HF=0, the IROUT waveform cannot modulate Fcarrier waveform when
in low-pulse width time. So IROUT waveform is determined by high-pulse time and
low-pulse time. This mode can produce standard PWM waveform
Fig. 24: LGP=0, HF=1, the IROUT waveform can modulate Fcarrier waveform when in
low-pulse width time. When IRE goes from high to low, the output waveform of IROUT
will keep on transmitting till high-pulse width timer interrupt occurs.
Fig. 25: LGP=0, HF=0, the IROUT waveform can not modulate Fcarrier waveform when
in low-pulse width time. So IROUT waveform is determined by high-pulse time and
low-pulse time. This mode can produce standard PWM waveform. When IRE goes from
high to low, the output waveform of IROUT will keep on transmitting till high-pulse width
timer interrupt occurs.
Fig.26: LGP=1, when this bit is set to high level, the high-pulse width timer is ignored. So
IROUT waveform output from low-pulse width timer is established.
Product Specification (V1.1) 04.11.2005
(This specification is subject to change without further notice)
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ELAN [ ELAN MICROELECTRONICS CORP ]
