PC87307VUL National Semiconductor, PC87307VUL Datasheet - Page 160

• Manufacturer Part Number: PC87307VUL
• Description: PC87307/PC97307 Plug and Play Compatible and PC97 Compliant SuperI/O
• Manufacturer: National Semiconductor

www.national.com
The Consumer-IR utilizes two carrier frequency ranges (see
also Table 7-28):
High and low frequencies are specified independently to al-
low separate transmission and reception modulation set-
tings. The transmitter uses the carrier frequency settings in
Table 7-28.
The four registers at offsets 04h through 07h (the infrared
transceiver configuration registers) are provided to config-
ure the Infrared Interface (the transceiver). The transceiver
mode is selected by up to three special output signals
(IRSL2-0). When programmed as outputs these signals are
forced to low when automatic configuration is enabled (AM-
CFG bit set to 1) and a UART mode is selected.
7.17.1 Infrared Receiver Demodulator Control
This register controls settings for Sharp-IR and Consumer
IR reception. After reset, the content of this register is 29h.
This setting selects a subcarrier frequency in a range be-
tween 34.61 KHz and 38.26 KHz for the Consumer-IR
mode, and from 480.0 to 533.3 KHz for the Sharp-IR mode.
The value of this register is ignored in both modes if the re-
ceiver demodulator is disabled. The available frequency
ranges for Consumer-IR and Sharp-IR modes are given in
Tables 7-25 through 7-27.
Bits 4-0 - Demodulator Frequency (DFR(4-0))
0
7
— Low range which spans from 30 KHz to 56 KHz, in 1
— High range which includes three frequencies:
These bits select the subcarrier’s center frequency for
the Consumer-IR receiver demodulator. Table 7-25
shows the selection for low speed demodulation (bit 5 of
Offset
05h
06h
07h
0
DBW2
6
KHz increments, and
400KHz, 450KHz or 480KHz.
FIGURE 7-35. IRRXDC Register Bitmap
Register (IRRXDC), Bank 7, Offset 0
DBW1
1
5
Register
IRCFG3
IRCFG4
DBW0
Name
0
4
1
3
DFR4
0
2
DFR3
Infrared Interface Configuration
Infrared Interface Configuration
0
1
DFR2
Reserved
1
0
DFR1
Reset
Required
UART1 and UART2 (with IR) (Logical Devices 5 and 6)
Description
DFR0
Register 3
Register 4
Demodulation Control
Register (IRRXDC)
Infrared Receiver
Offset 00h
Bank 7,
160
Bits 7-5 - Demodulator Bandwidth (DBW(2-0))
7.17.2 Infrared Transmitter Modulator Control
This register controls modulation subcarrier parameters for
Consumer-IR and Sharp-IR mode transmission. For Sharp-
IR, only the carrier pulse width is controlled by this register
- the carrier frequency is fixed at 500 KHz.
After reset, the value of this register is 69h, selecting a car-
rier frequency of 36 KHZ and an IR pulse width of 7 sec for
Consumer-IR, or a pulse width of 0.8 sec for Sharp-IR.
Bits 4-0 - Modulation Subcarrier Frequency (MCFR)
These bits set the frequency for the Consumer-IR modula-
tion subcarrier. The encoding are defined in Table 7-28. Bits
7-5 - Modulation Subcarrier Pulse Width (MCPW)
0
7
RCCFG=0, see page 163), and Table 7-26 shows the
selection for high speed demodulation (bit 5 of RC-
CFG=1).
These bits set the demodulator bandwidth for the select-
ed frequency range. The subcarrier signal frequency
must fall within the specified frequency range in order to
be accepted. Used for both Sharp-IR and Consumer-IR
modes.
See Tables 7-25, 7-26 and bit 5 (RXHSC) of the Con-
sumer-IR Configuration (RCCFG) Register on page
163.
Specify the pulse width of the subcarrier clock as shown
in Table 7-29.
1
6
FIGURE 7-36. IRTXMC Register Bitmap
Register (IRTXMC), Bank 7, Offset 01h
1
5
MCPW(2-0)
0
4
1
3
0
2
0
1
MCFR(4-0)
1
0
Reset
Required
Infrared Transmitter
Modulation Control
Offset 01h
(IRTXMC)
Register
Bank 7,