1.3.2.4.1.4.4 SYSCLK2 Clock Counter (SYSCLK2CNTR) Register
Since COUNT will begin updating as soon as reset is released, the value of this register after reset will be
non-zero before software can read it. SYSCLK2CNTR will tap off the clock after the /2 from PLL2OUT, if it is
enabled. If not enabled, it will tap off PLL2OUT.
Figure 1-32. SYSCLK2 Clock Counter (SYSCLK2CNTR) Register
15
0
COUNT
R/C-0x0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-30. SYSCLK2 Clock Counter (SYSCLK2CNTR) Register Field Descriptions
Bit
Field
Value
Description
15-0
COUNT
SYSCLK2 Counter Bit Field: This bit field is a free-running counter based off the SYSCLK2 clock.
Software can compare the rate of update of this bit field against the rate of update of a CPU Timer
to determine at what approximate frequency the SYSCLK2 clock is running.
1.3.2.4.1.4.5 EPWM DMA/CLA Configuration (EPWMCFG) Register
Figure 1-33. EPWM DMA/CLA Configuration (EPWMCFG) Register
15
1
0
Reserved
CONFIG
R-0
R/W-0X0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 1-31. EPWM DMA/CLA Configuration (EPWMCFG) Register Field Descriptions
Bit
Field
Value
Description
15-1
Reserved
Any writes to these bits must always have a value of 0.
0
CONFIG
EPWM DMA Enable Bit:
0
The EPWM blocks are connected to the CLA bus and are inaccessible to the DMA bus
1
The EPWM blocks are connected to the DMA bus and are inaccessible to the CLA bus
1.3.2.5 Input Clock Fail Detection
It is possible for the clock source of the device to fail. When the PLL is not disabled, the main oscillator fail logic
allows the device to detect this condition and handle it as described in this section.
Two counters are used to monitor the presence of the OSCCLK signal as shown in
is incremented by the OSCCLK signal itself. When the PLL is not turned off, the second counter is incremented
by the VCOCLK coming out of the PLL block. These counters are configured such that when the 7-bit OSCCLK
counter overflows, it clears the 13-bit VCOCLK counter. In normal operating mode, as long as OSCCLK is
present, the VCOCLK counter will never overflow.
If the OSCCLK input signal is missing, then the PLL will output a default limp mode frequency and the VCOCLK
counter will continue to increment. Since the OSCCLK signal is missing, the OSCCLK counter will not increment,
and therefore, the VCOCLK counter is not periodically cleared. Eventually, the VCOCLK counter overflows. This
signals a missing clock condition to the missing-clock-detection logic. What happens next is based on which
clock source has been chosen for the PLL and the value of NMIRESETSEL.
System Control and Interrupts
84
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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