Automatic Cycle Adjustment
191
SNIU028A – February 2016 – Revised April 2016
Copyright © 2016, Texas Instruments Incorporated
Loop Mux
5.13.2 Configuration
Most of the control is in the CYCADJCTRL register.
The measurement starts after a DPWMxA rising edge selected by CYC_ADJ_SYNC. After the rising edge,
the logic waits for a sample from the Front End selected by FIRST_SAMPLE_SEL.
After the first sample, the logic waits for a sample from the Front End selected by
SECOND_SAMPLE_SEL. After that, it calculates D
adj
and presents it to the DPWM modules.
All the bit-fields mentioned above are in CYCADJCTRL. There is also a CYC_ADJ_EN bit to enable
automatic cycle adjustment.
To enable the DPWM to accept the adjustment, it is necessary to set the CLA_DUTY_ADJ_EN bit in
DPWMCTRL1.
It is also necessary to provide sample triggers to the EADC, of course.
To prevent excessive adjustment in the event of a measurement failure, the Cycle Adjustment Limit
Register (CYCADJLIM) provides upper and lower limits for the
5.13.3 Scaling
The EADC error signal is scaled at a nominal 1 mV. The output of the Automatic Cycle Adjust Module is
scaled at normal resolution – 1 step = 4 ns.
So if
is 1 mV, and CYC_ADJ_GAIN is 0, the cycle adjustment will be 4 nanoseconds. This will
make the duty cycle on any DPWM with CLA_DUTY_ADJ_EN set 4 nanoseconds longer.
5.14 Loop Mux Registers Reference
5.14.1 Front End Control 0 Mux Register (FECTRL0MUX)
Address 00020000
Figure 5-2. Front End Control 0 Mux Register (FECTRL0MUX)
13
12
11
10
9
8
NL_SEL
DPWM3_FRAME_
SYNC_EN
DPWM2_FRAME_
SYNC_EN
DPWM1_FRAME_
SYNC_EN
DPWM0_FRAME_
SYNC_EN
R/W-00
R/W-0
R/W-0
R/W-0
R/W-0
7
6
5
4
3
2
1
0
DPWM3_B_
TRIG_EN
DPWM2_B_
TRIG_EN
DPWM1_B_
TRIG_EN
DPWM0_B_
TRIG_EN
DPWM3_A_
TRIG_EN
DPWM2_A_
TRIG_EN
DPWM1_A_
TRIG_EN
DPWM0_A_
TRIG_EN
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 5-2. Front End Control 0 Mux Register (FECTRL0MUX) Register Field Descriptions
Bit
Field
Type
Reset
Description
13-12
NL_SEL
R/W
00
Configures source of Non-Linear (NL) comparison results used in Automatic Gain
Shifting
0 = Filter 0 NL Results used
1 = Filter 1 NL Results used
2 = Filter 2 NL Results used (Default)
11
DPWM3_FRAME_
SYNC_EN
R/W
0
Enables DPWM Trigger from DPWM 3 Frame Sync to Front End Control
0 = DPWM 3 Frame Sync not routed to Front End Control (Default)
1 = DPWM 3 Frame Sync routed to Front End Control
10
DPWM2_FRAME_
SYNC_EN
R/W
0
Enables DPWM Trigger from DPWM 2 Frame Sync to Front End Control
0 = DPWM 2 Frame Sync not routed to Front End Control (Default)
1 = DPWM 2 Frame Sync routed to Front End Control