Inter-Integrated Circuit Controller
7-85
MPU Public Peripherals
System Test Enable (ST_EN)
This bit (15) must be set to 1 to permit other system test registers bits to be set.
-
0: Normal mode
-
1: System test enabled
Value after reset is low.
Free Running Mode After Breakpoint (FREE)
This bit (14) is used to determine the state of the I
2
C controller when a break-
point is encountered in the HLL debugger. This bit can be set independently
of the ST_EN value.
FREE = 0: Stops immediately if SCL is low and keeps driving SCL low whether
I
2
C is master transmitter/receiver. If SCL is high, I
2
C waits until SCL becomes
low and then stops. If the I
2
C is a slave, it stops when the transmission/
receiving completes.
FREE = 1: The I
2
C runs free.
-
0: Stop mode (on breakpoint condition)
-
1: Free-running mode
Value after reset is low.
Test Mode Select (TMODE)
In normal functional mode (ST_EN = 0), these bits (13-12) are don’t care. They
read always as 00 and a write is ignored.
In system test mode (ST_EN = 1), these bits can be set according to the follow-
ing table to permit various system tests.
Table 7–72. TMODE Settings
TMODE
Mode
00
Functional mode (default)
01
Reserved
10
Test of SCL counters (SCLL, SCLH, PSC)
11
Loop back mode SDA/SCL IO mode select