LM3S3749 Luminary Micro, Inc, LM3S3749 Datasheet - Page 630

• Manufacturer Part Number: LM3S3749
• Description: Lm3s3749 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

Pulse Width Modulator (PWM)
630
Bit/Field
18
17
MINFLTPER
LATCH
Name
Type
R/W
R/W
Reset
0
0
Preliminary
Description
Latch Fault Input
This bit controls the behavior of the fault condition in a PWM generator.
The fault condition may be latched and internally asserted because the
fault condition logic includes the generator’s IntFaultn bit (of the
PWMISC register) enabled by the LATCH bit.
Therefore, if the PWMINTEN IntFaultn bit is set, a fault condition
sets the PWMISC IntFaultn bit (generating an interrupt) and the fault
condition is extended in the generator logic until software clears the
PWMISC IntFaultn bit.
Minimum Fault Period
This bit specifies that the PWM generator enables a one-shot counter
to provide a minimum fault condition period.
The timer begins counting on the rising edge of the fault condition to
extend the condition for a minimum duration of the count value. The
timer ignores the state of the fault condition while counting.
The minimum fault delay is in effect only when the MINFLTPER bit is
set. If a detected fault is in the process of being extended when the
MINFLTPER bit is cleared, the fault condition extension is aborted.
The delay time is specified by the PWMnMINFLTPER register MFP field
value. The effect of this is to pulse stretch the fault condition input.
The delay value is defined by the PWM clock period. Because the fault
input is not synchronized to the PWM clock, the period of the time is
PWMClock * (MFP value + 1) or PWMClock * (MFP value + 2).
The delay function makes sense only if the fault source is unlatched. A
latched fault source makes the fault condition appear asserted until
cleared by software and negates the utility of the extend feature. It
applies to all fault condition sources as specified in the FLTSRC field.
Value
0
1
Value
0
1
Description
Fault Condition Not Latched
A fault condition is in effect for as long as the generating source
is asserting.
Fault Condition Latched
A fault condition is set as the result of the assertion of the
faulting source and is held (latched) while the PWMISC
IntFaultn bit is set. Clearing the IntFaultn bit clears the
fault condition.
Description
Fault Condition Period Not Extended
The FAULT input deassertion is unaffected.
Fault Condition Period Extended
The PWMnMINFLTPER one-shot counter is active and extends
the period of the fault condition to a minimum period.
June 02, 2008