I2C Registers
Table 21-12. I2C_IRQSTATUS_RAW Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
2
ARDY
R/W
0h
I2C mode only.
This read/clear only bit, when set to 1, indicates that the previously
programmed data and command (receive or transmit, master or
slave) has been performed and status bit has been updated.
The CPU uses this flag to let it know that the I2C registers are ready
to be accessed again.
The CPU can only clear this bit by writing a 1 into this register.
A write 0 has no effect.
Mode: I2C Master transmit, Others: STP = 1, ARDY Set Condition:
DCOUNT = 0.
Mode: I2C Master receive, Others: STP = 1, ARDY Set Condition:
DCOUNT = 0 and receiver FIFO empty Mode: I2C Master transmit,
Others: STP = 0, ARDY Set Condition: DCOUNT passed 0 Mode:
I2C Master receive, Others: STP = 0, ARDY Set Condition:
DCOUNT passed 0 and receiver FIFO empty Mode: I2C Master
transmit, Others: n/a, ARDY Set Condition: Stop or restart condition
received from master Mode: I2C Slave receive, Others: n/a, ARDY
Set Condition: Stop or restart condition and receiver FIFO empty
Value after reset is low.
0x0 = No action
0x1 = Access ready
1
NACK
R/W
0h
No acknowledgment IRQ status.
Bit is set when No Acknowledge has been received, an interrupt is
signaled to MPUSS.
Write '1' to clear this bit.
I2C mode only.
The read/clear only No Acknowledge flag bit is set when the
hardware detects No Acknowledge has been received.
When a NACK event occurs on the bus, this bit is set to 1, the core
automatically ends the transfer and clears the MST/STP bits in the
I2C_CON register and the I2C becomes a slave.
Clearing the FIFOs from remaining data might be required.
The CPU can only clear this bit by writing a 1 into this register.
Writing 0 has no effect.
Value after reset is low.
0x0 = Normal operation
0x1 = Not Acknowledge detected
0
AL
R/W
0h
Arbitration lost IRQ status.
This bit is automatically set by the hardware when it loses the
Arbitration in master transmit mode, an interrupt is signaled to
MPUSS.
During reads, it always returns 0.
I2C mode only.
The read/clear only Arbitration Lost flag bit is set to 1 when the
device (configured in master mode) detects it has lost an arbitration
(in Address Phase).
This happens when two or more masters initiate a transfer on the
I2C bus almost simultaneously or when the I2C attempts to start a
transfer while BB (bus busy) is 1.
When this is set to 1 due to arbitration lost, the core automatically
clears the MST/STP bits in the I2C_CON register and the I2C
becomes a slave receiver.
The CPU can only clear this bit by writing a 1 to this register.
Writing 0 has no effect.
Value after reset is low.
0x0 = Normal operation
0x1 = Arbitration lost detected
3726
I2C
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated