UPSD325X datasheet(79/176 Pages) STMICROELECTRONICS

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µPSD325X DEVICES

Serial Status Register (SxSTA: S1STA, S2STA)

SxSTA is a “Read-only” register. The contents of

this register may be used as a vector to a service

routine. This optimized the response time of the

software and consequently that of the I2C-bus.

The status codes for all possible modes of the I2C-

bus interface are given Table 54.

This flag is set, and an interrupt is generated, after

any of the following events occur.

1. Own slave address has been received during

AA = 1: ack_int

2. The general call address has been received

while GC(SxADR.0) = 1 and AA = 1:

3. A data byte has been received or transmitted in

Master Mode (even if arbitration is lost): ack_int

4. A data byte has been received or transmitted as

selected slave: ack_int

5. A stop condition is received as selected slave

receiver or transmitter: stop_int

Data Shift Register (SxDAT: S1DAT, S2DAT)

SxDAT contains the serial data to be transmitted

or data which has just been received. The MSB

(Bit 7) is transmitted or received first; that is, data

shifted from right to left.

Table 53. Serial Status Register (SxSTA)

Table 54. Description of the SxSTA Bits

Note: 1. Interrupt Flag Bit (INTR, SxSTA Bit 5) is cleared by Hardware as reading SxSTA register.

2. I2C interrupt flag (INTR) can occur in below case. (except DDC2B Mode at SWENB=0)

Table 55. Data Shift Register (SxDAT: S1DAT, S2DAT)

76543210

STOP

INTR

TX_MODE

BBUSY

BLOST

/ACK_REP

SLV

Bit

Symbol

Function

General Call Flag

STOP

Stop Flag. This bit is set when a STOP condition is received

INTR

Interrupt Flag. This bit is set when an I²C Interrupt condition is requested

TX_MODE

Transmission Mode Flag.

This bit is set when the I²C is a transmitter; otherwise this bit is reset

BBUSY

Bus Busy Flag.

This bit is set when the bus is being used by another master; otherwise, this bit is reset

BLOST

Bus Lost Flag.

This bit is set when the master loses the bus contention; otherwise this bit is reset

/ACK_REP

Acknowledge Response Flag.

This bit is set when the receiver transmits the not acknowledge signal

This bit is reset when the receiver transmits the acknowledge signal

0SLV

Slave Mode Flag.

This bit is set when the I²C plays role in the Slave Mode; otherwise this bit is reset

76543210

SxDAT7

SxDAT6

SxDAT5

SxDAT4

SxDAT3

SxDAT2

SxDAT1

SxDAT0

UPSD325X 数据表(PDF) 79 Page - STMicroelectronics

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