TUSB3410 datasheet(53/92 Pages) TI

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7–7

CTS

MSR

MCR

(4) LCTS

(5) LDSR

(6) LRI

(7) LCD

(5) RTS

(4) DTR

(6) LRI

(7) LCD

(2) LOOP

DSR

DCD

RTS

DTR

Figure 7–1. MSR and MCR Registers in Loop-Back Mode

7.1.8

MSR: Modem-Status Register (Addr:FFA6)

This register provides information about the current state of the control lines from the modem.

765

LCD

LRI

LDSR

LCTS

∆CD

TRI

∆DSR

∆CTS

R/O

R/C

BIT

NAME

RESET

FUNCTION

∆CTS

This bit indicates that the CTS input has changed state. Cleared when the MCU writes a 1 to this bit.

Writing a 0 has no effect.

∆CTS = 0

∆CTS = 1

Indicates no change in the CTS input

Indicates that the CTS input has changed state since the last time it was read. Clears when the

MCU writes a 1. Writing a 0 has no effect.

∆DSR

This bit indicates that the DSR input has changed state. Cleared when the MCU writes a 1 to this bit.

Writing a 0 has no effect.

∆DSR = 0

∆DSR = 1

Indicates no change in the DSR input

Indicates that the DSR input has changed state since the last time it was read. Clears when the

MCU writes a 1. Writing a 0 has no effect.

TRI

Trailing edge of the ring indicator. This bit indicates that the RI input has changed from low to high. This bit

is cleared when the MCU writes a 1 to this bit. Writing a 0 has no effect.

TRI = 0

TRI = 1

Indicates no applicable transition on the RI input

Indicates that an applicable transition has occurred on the RI input.

∆CD

This bit indicates that the CD input has changed state. Cleared when the MCU writes a 1 to this bit. Writing

a 0 has no effect.

∆CD = 0

∆CD = 1

Indicates no change in the CD input

Indicates that the CD input has changed state since the last time it was read.

LCTS

During loopback, this bit reflects the status of MCR[1] (see Figure 7–1)

LCTS = 0

LCTS = 1

CTS input is high

CTS input is low

LDSR

During loop back, this bit reflects the status of MCR[0] (see Figure 7–1).

LDSR = 0

LDSR= 1

DSR input is high

DSR input is low

LRI

During loop back, this bit reflects the status of MCR[2] (see Figure 7–1).

LRI = 0

LRI = 1

RI input is high

RI input is low

TUSB3410 データシート(PDF) 53 Page - Texas Instruments

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