Table 1-25. PLL Status Register (PLLSTS) Field Descriptions (continued)
Bits
Field
Value
Description
3
MCLKSTS
Missing Clock Status Bit. Check the status of this bit after a reset to determine whether a missing
oscillator condition was detected. Under normal conditions, this bit should be 0. Writes to this bit
are ignored. This bit will be cleared by writing to the MCLKCLR bit or by forcing an external reset.
0
Indicates normal operation. A missing clock condition has not been detected.
1
Indicates that OSCCLK was detected as missing. The main oscillator fail detect logic has reset the
device and the CPU is now clocked by the PLL operating at the limp mode frequency.
When the missing clock detection circuit automatically switches between OSCCLKSRC2 to
OSCCLKSRC1 (upon detecting OSCCLKSRC2 failure), this bit will be automatically cleared and
the missing clock detection circuit will be re-enabled. For all other cases, the user needs to
re-enable this mode by writing a 1 to the MCLKCLR bit.
2
PLLOFF
PLL Off Bit. This bit turns off the PLL. This is useful for system noise testing. This mode must only
be used when the PLLCR register is set to 0x0000.
0
PLL On (default)
1
PLL Off. While the PLLOFF bit is set the PLL module will be kept powered down.
The device must be in PLL bypass mode (PLLCR = 0x0000) before writing a 1 to PLLOFF. While
the PLL is turned off (PLLOFF = 1), do not write a non-zero value to the PLLCR.
The STANDBY and HALT low power modes will work as expected when PLLOFF = 1. After waking
up from HALT or STANDBY the PLL module will remain powered down.
1
Reserved
Any writes to these bits must always have a value of 0.
0
PLLLOCKS
PLL Lock Status Bit.
0
Indicates that the PLLCR register has been written to and the PLL is currently locking. The CPU is
clocked by OSCCLK/2 until the PLL locks.
1
Indicates that the PLL has finished locking and is now stable.
(1)
This register is reset to its default state only by the XRS signal or a watchdog reset. It is not reset by a missing clock or debugger reset.
(2)
This register is EALLOW protected. See
for more information.
System Control and Interrupts
80
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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