PMM Operation
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SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Power Management Module (PMM) and Supply Voltage Supervisor (SVS)
In an application, it may be desired to cause a BOR through software. Setting PMMSWBOR causes a
software-driven BOR. PMMBORIFG is set accordingly. Note that a BOR also initiates a POR and PUC.
PMMBORIFG can be cleared by software or by reading SYSRSTIV. Similarly, it is possible to cause a
POR through software by setting PMMSWPOR. PMMPORIFG is set accordingly. A POR also initiates a
PUC. PMMPORIFG can be cleared by software or by reading SYSRSTIV. Both PMMSWBOR and
PMMSWPOR are self clearing. See the SYS module for complete descriptions of BOR, POR, and PUC
resets.
2.2.6 RST/NMI
The external RST/NMI terminal is pulled low on a BOR reset condition. The RST/NMI can be used as
reset source for the rest of the application.
2.2.7 PMM Interrupts
Interrupt flags generated by the PMM are routed to the system NMI interrupt vector generator register,
SYSSNIV. When the PMM causes a reset, a value is generated in the system reset interrupt vector
generator register, SYSRSTIV, corresponding to the source of the reset. These registers are defined
within the SYS module. More information on the relationship between the PMM and SYS modules is
available in the SYS chapter.
2.2.8 Port I/O Control
The PMM provides a means of ensuring that I/O pins cannot behave in uncontrolled fashion during an
undervoltage event. During these times, outputs are disabled, both normal drive and the weak pullup or
pulldown function. If the CPU is functioning normally, and then an undervoltage event occurs, any pin
configured as an input has its PxIN register value locked in at the point the event occurs, until voltage is
restored. During the undervoltage event, external voltage changes on the pin are not registered internally.
This helps prevent erratic behavior from occurring.