I2C Registers
Table 21-33. I2C_SYSTEST Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
14
FREE
R/W
0h
Free running mode (on breakpoint).
This bit is used to determine the state of the I2C controller when a
breakpoint is encountered in the HLL debugger.
Note: This bit can be set independently of ST_EN value.
FREE =
0: the I2C controller stops immediately after completion of the on-
going bit transfer.
Stopping the transfer is achieved by forcing the SCL line low.
Note that in this case there will be no status register updates.
FREE =
1: the I2C interface runs free.
When Suspend indication will be asserted, there will be no accesses
on the OCP Interface (the CPU is in debug mode) and consequently
the FIFOs will reach full/empty state (according to RX or TX modes)
and the I2C SDA line will be kept low.
Note that the status registers will be updated, but no DMA, IRQ or
WakeUp will be generated.
The status registers likely to be updated in this mode are:
I2C_IRQSTATUS_RAW.XRDY, I2C_IRQSTATUS_RAW.RRDY,
I2C_IRQSTATUS_RAW.XUDF, I2C_IRQSTATUS_RAW.ROVR,
I2C_IRQSTATUS_RAW.ARDY and I2C_IRQSTATUS_RAW.NACK.
Value after reset is low.
0x0 = Stop mode (on breakpoint condition). If Master mode, it stops
after completion of the on-going bit transfer. In slave mode, it stops
during the phase transfer when 1 byte is completely
transmitted/received.
0x1 = Free running mode
13-12
TMODE
R/W
0h
Test mode select.
In normal functional mode (ST_EN = 0), these bits are don't care.
They are always read as 00 and a write is ignored.
In system test mode (ST_EN = 1), these bits can be set according to
the following table to permit various system tests.
Values after reset are low (2 bits).
SCL counter test mode: in this mode, the SCL pin is driven with a
permanent clock as if mastered with the parameters set in the
I2C_PSC, I2C_SCLL, and I2C_SCLH registers.
Loop back mode: in the master transmit mode only, data transmitted
out of the I2C_DATA register (write action) is received in the same
I2C_DATA register via an internal path through the FIFO buffer.
The DMA and interrupt requests are normally generated if enabled.
SDA/SCL IO mode: in this mode, the SCL IO and SDA IO are
controlled via the I2C_SYSTEST
[5:0] register bits.
0x0 = Functional mode (default)
0x1 = Reserved
0x2 = Test of SCL counters (SCLL, SCLH, PSC). SCL provides a
permanent clock with master mode.
0x3 = Loop back mode SDA/SCL IO mode select
11
SSB
R/W
0h
Set status bits.
Writing 1 into this bit also sets the 6 read/clear-only status bits
contained in I2C_IRQSTATUS_RAW register (bits
5:0) to 1.
Writing 0 into this bit doesn't clear status bits that are already set
only writing 1 into a set status bit can clear it (see
I2C_IRQSTATUS_RAW operation).
This bit must be cleared prior attempting to clear a status bit.
Value after reset is low.
0x0 = No action.
0x1 = Set all interrupt status bits to 1.
10-9
Reserved
R
0h
3758
I2C
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated