LSI Logic Confidential
SIO IR (Infrared) Interface
15-3
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
15.1.1 IR Transmit Functionality
The IR interface block controls the output to the IR “blaster” pin
SIO_IRTX*. The IR transmit circuit allows the host to program the period
and the pulse-high width of the carrier signal. The IR registers allow
carriers in the range of 4.58 kHz to 10 MHz with full control of the duty
cycle.
The IR interface controls the carrier frequency and the envelope of the
modulated pulse. Communication with an external device requires the
carrier frequency of the IR interface to match the IR receiver in the target
device. The IR interface can then send control messages by generating
sequences of pulses with varying envelopes.
The period and duty cycle of the carrier and modulated signal are set via
the CWP/CWPH and MSPL/MSPR Registers, respectively.
To program the modulated signal’s pulse shape, the pulse’s period and
pulse-low width are programmed with the period programmed last. Bit 26
of the Transmit Period register (IR_MSPR) is the Transmit Enable bit.
When programmed to one, this bit indicates that the pulse shape values
should be loaded immediately after the completion of the current pulse
3
CWP
IRTX Carrier Wave Period:
User can program period of carrier waveform,
in units of sysclk cycles
0x0 + 1
sysclk
cycles
1
sysck
cycles
4
CWPH
IRTX Carrier Wave Period High:
User can program duty cycle of carrier
waveform, in units of sysclk cycles
0x0 + 1
sysclk
cycles
1
sysclk
cycles
5
RTP
IRRX Receive Tick Period:
User can program length of an “IR tick”, in
terms of sysclk cycles
0x0 + 1
sysclk
cycles
1
sysclk
cycles
6
RTC
IRRX Receive Tick Count:
IR module counts number of IR ticks between
successive falling (or rising) edges of IRRX
0x0 + 1
IR ticks
0xff + 1
IR ticks
7
RPH
IRRX Receive High Tick Count:
IR module counts number of IR ticks that
IRRX is high
0x0 + 1
IR ticks
0xff + 1
IR ticks
Table 15.1
IR Waveform/Register Value Relationship
Reference
Parameter
Description
Minimum
Maximum
Содержание DMN-8600
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