I2C Registers
Table 21-12. I2C_IRQSTATUS_RAW Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
4
XRDY
R/W
0h
Transmit data ready IRQ status.
Set to '1' by core when transmitter and when new data is requested.
When set to '1' by core, an interrupt is signaled to MPUSS.
Write '1' to clear.
Transmit mode only (I2C mode).
This read/clear only bit (XRDY) is set to 1 when the I2C peripheral is
a master or slave transmitter, the CPU needs to send data through
the I2C bus, and the module (transmitter) requires new data to be
served.
Note that a master transmitter requests new data if the FIFO TX
level is below the threshold (TXTRSH) and the required amount of
data remained to be transmitted (I2C_BUFSTAT.TXSTAT) is greater
than the threshold.
A slave transmitter requests new data when the FIFO TX level is
below the threshold (if TXTRSH > 1), or anytime there is a read
request from external master (for each acknowledge received from
the master), if TXTRSH = 1.
When this bit is set to 1 by the core, an interrupt is signaled to the
local host if the interrupt was enabled.
The CPU can also poll this bit (refer to the FIFO Management
subsection for details about XRDY generation).
The CPU can only clear this bit by writing a 1 into this register.
Writing 0 has no effect.
Note: If the DMA transmit mode is enabled (I2C_BUF.XDMA_EN is
set, together with I2C_DMATXENABLE_SET), this bit is forced to 0
and no interrupt will be generated
instead, a DMA TX request to the main DMA controller of the system
is generated.
Value after reset is low.
0x0 = Transmission ongoing
0x1 = Transmit data ready
3
RRDY
R/W
0h
Receive mode only (I2C mode).
This read/clear only RRDY is set to 1 when the RX FIFO level is
above the configured threshold (RXTRSH).
When this bit is set to 1 by the core, CPU is able to read new data
from the I2C_DATA register.
If the corresponding interrupt was enabled, an interrupt is signaled to
the local host.
The CPU to read the received data in I2C_DATA register can also
poll this bit (refer to the FIFO Management subsection for details
about RRDY generation).
The CPU can only clear this bit by writing a 1 into this register.
A write 0 has no effect.
If the DMA receive mode is enabled (I2C_BUF.RDMA_EN is set,
together with I2C_DMARXENABLE_SET), this bit is forced to 0 and
no interrupt will be generated
instead a DMA RX request to the main DMA controller of the system
is generated.
Value after reset is low.
0x0 = Receive FIFO threshold not reached
0x1 = Receive data ready for read (RX FIFO threshold reached)
3725
SPRUH73H – October 2011 – Revised April 2013
I2C
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