Maxim Integrated DS4830 Optical Microcontroller - Manual (Page 86)

DS4830 User’s Guide
86
10.2.2 – I 2
C Master Status Register (I2CST_M)
Address: M1[01h]
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name I2CBUS I2CBUSY - - I2CSPI I2CSCL I2CROI I2CGCI I2CNACKI - I2CAMI I2CTOI I2CSTRI I2CRXI I2CTXI I2CSRI
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Access r* r* r r rw r* rw rw rw* r rw rw rw* rw* rw rw
* Set by hardware only.
BIT NAME DESCRIPTION
15 I2CBUS I
2
C Master Bus Busy. This bit is set to ‘1’ when a START/repeated START
condition is detected and cleared to 0 when the STOP condition is detected. This bit
is reset to ‘0’ when I2CEN=0. This bit is controlled by hardware and is read only.
14 I2CBUSY I
2
C Master Busy. This bit is used to indicate the current status of the I
2
C controller.
The I2CBUSY is set to ‘1’ when the I 2
C controller is actively participating in a
transaction. This bit is controlled by hardware and is read only.
13:12 Reserved Reserved. The user should write 0 to these bits.
11 I2CSPI I
2
C Master STOP Interrupt Flag. This bit is set to ‘1’ when a STOP condition is
detected. This bit must be cleared to ‘0’ by software once set. Setting this bit to ‘1’
by software will cause an interrupt if enabled.
10 I2CSCL I
2
C Master SCL Status. This bit reflects the logic state of the SCL signal. This bit is
set to ‘1’ when SCL is at a high logic level and cleared to ‘0’ when SCL is at a low
logic level. This bit is controlled by hardware and is read only.
9 I2CROI I
2
C Master Receiver Overrun Flag. This bit indicates a receive overrun when set to
‘1’. This bit is set to ‘1’ if the receiver has received two bytes since the last software
reading of I2CBUF_M. This bit can only be cleared to
‘0’ by software reading
I2CBUF_M. Setting this bit to ‘1’ by software will cause an interrupt if enabled.
8 I2CGCI I
2
C General Call Interrupt Flag. This bit has no function when operating in master
mode.
7 I2CNACKI I
2
C Master NACK Interrupt Flag. This bit is set by hardware to ‘1’ if a NACK was
received from a slave or a 0 if an ACK was received from a slave. The setting of
this bit to
‘1’ will cause an interrupt if enabled. This bit can be cleared to ‘0’ by
software once set. This bit is set by hardware only.
6 Reserved Reserved. The user should write 0 to this bit.
5 I2CAMI I
2
C Address Match Interrupt Flag. This bit has no function when operating in
master mode.
4 I2CTOI I
2
C Master Timeout Interrupt Flag. This bit is set to ‘1’ if the I 2 C controller cannot
generate a START or STOP condition or the SCL low time is greater than the
timeout value specified in the I2CTO_M register. This bit must be cleared to
‘0’ by
software once set. Setting this bit to ‘1’ by software causes an interrupt if enabled.
3 I2CSTRI I
2
C Master Clock Stretch Interrupt Flag. This bit is set to ‘1’ to indicate that the I
2
C
master controller is operating with clock stretching enabled and is currently holding
the SCL clock signal low. The I
2 C controller will release SCL after this bit has been
cleared to ‘0’. This bit must be cleared to ‘0’ by software once set. This bit is set by
hardware only.
2 I2CRXI I
2
C Master Receive Ready Interrupt Flag. This bit is set to ‘1’ to indicate that a
data byte has been received in I2CBUF_M. This bit must be cleared to ‘0’ by
software once set. This bit is set by hardware only.
1 I2CTXI I
2
C Master Transmit Complete Interrupt Flag. This bit is set to ‘1’ to indicate that
an address or a data byte has been successfully shifted out and the I
2
C controller
has received an acknowledgment from the receiver (ACK or NACK). This bit must
be cleared
to ‘0’ by software once set. Setting this bit to ‘1’ by software will cause an
interrupt if enabled.
0 I2CSRI I
2
C Master START Interrupt Flag. This bit is set to ‘1’ when a START condition (or
restart) is detected. This bit must be cleared to ‘0’ by software once set. Setting this
bit to ‘1’ by software will cause an interrupt if enabled.