PC97307 datasheet(160/218 Pages) NSC

160 / 218 page

160

UART1 and UART2 (with IR) (Logical Devices 5 and 6)

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The Consumer-IR utilizes two carrier frequency ranges (see

also Table 7-28):

— Low range which spans from 30 KHz to 56 KHz, in 1

KHz increments, and

— High range which includes three frequencies:

400KHz, 450KHz or 480KHz.

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.

FIGURE 7-35. IRRXDC Register Bitmap

Bits 4-0 - Demodulator Frequency (DFR(4-0))

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

05h

Reserved

06h

IRCFG3

Infrared Interface Conﬁguration

07h

IRCFG4

Infrared Interface Conﬁguration

Offset

Name

Description

76543210

Reset

Required

Bank 7,

Demodulation Control

Infrared Receiver

DFR2

DFR4

DBW0

DBW1

DBW2

DFR0

DFR1

DFR3

Offset 00h

RCCFG=0, see page 163), and Table 7-26 shows the

selection for high speed demodulation (bit 5 of RC-

CFG=1).

Bits 7-5 - Demodulator Bandwidth (DBW(2-0))

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.

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

µsec for

Consumer-IR, or a pulse width of 0.8

µsec for Sharp-IR.

FIGURE 7-36. IRTXMC Register Bitmap

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)

Specify the pulse width of the subcarrier clock as shown

in Table 7-29.

76543210

Reset

Required

Modulation Control

(IRTXMC)

Bank 7,

Infrared Transmitter

MCFR(4-0)

MCPW(2-0)

Offset 01h

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