ST & T UPSD3212C - Manual (Page 74)

uPSD3212A, uPSD3212C, uPSD3212CV
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Serial Status Register (S2STA)
S2STA 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 I
2
C bus. The
status codes for all possible modes of the I
2
C 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(S2ADR.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 (S2DAT)
S2DAT 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 (S2STA)
Table 54. Description of the S2STA Bits
Note: 1. Interrupt Flag Bit (INTR, S2STA Bit 5) is cleared by Hardware as reading S2STA register.
2. I 2 C Interrupt Flag (INTR) can occur in below case.
Table 55. Data Shift Register (S2DAT)
7 6 5 4 3 2 1 0
GC STOP INTR TX_MODE BBUSY BLOST /ACK_REP SLV
Bit Symbol Function
7 GC General Call Flag
6 STOP Stop Flag. This bit is set when a STOP condition is received
5 INTR
(1,2) Interrupt Flag. This bit is set when an I²C Interrupt condition is requested
4 TX_MODE
Transmission Mode Flag.
This bit is set when the I²C is a transmitter; otherwise this bit is reset
3 BBUSY
Bus Busy Flag.
This bit is set when the bus is being used by another master; otherwise, this bit is reset
2 BLOST
Bus Lost Flag.
This bit is set when the master loses the bus contention; otherwise this bit is reset
1 /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
0 SLV
Slave Mode Flag.
This bit is set when the I²C plays role in the Slave Mode; otherwise this bit is reset
7 6 5 4 3 2 1 0
S2DAT7 S2DAT6 S2DAT5 S2DAT4 S2DAT3 S2DAT2 S2DAT1 S2DAT0