PC87591L datasheet(140/437 Pages) NSC

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Note that TnCNT2 can not operate in the Pulse Accumulate or External Event Counter modes since TBn input is used as a

capture input. Selecting either Pulse Accumulate mode or External Event Counter mode for TnCNT2 causes TnCNT2 to stop.

Note, however, that all available clock source modes may be selected for TnCNT1. Thus it is possible to use TnCNT1 to

determine the number of capture events on TBn or the elapsed time between capture events on TBn.

4.7.4

Timer Interrupts

The MFT16 contains a total of four interrupt sources that are mapped to two different system interrupts. All sources have a

pending flag associated with them and can be enabled or disabled under software control. The pending flags are TnXPND,

where n is the module and X is a letter from A to D. An interrupt enable flag, TnXIEN, is associated with each interrupt pend-

ing flag. Interrupt sources A, B or C can generate a timer interrupt 1; interrupt source D can generate a timer interrupt 2.

Note that not all interrupt sources are available in all modes. Table 19 shows which events can trigger an interrupt in each

mode of operation:

Table 19. MFT16 Interrupts

System

Interrupt

Pending

Flag

Mode 1

Mode 2

Mode 3

Mode 4

PWM and Counter

Dual Input Capture

Dual Independent

Timer

Input Capture and

Timer

Int. 1

TnAPND

TnCNT1 reload from

TnCRA

Input capture on TAn

transition

TnCNT1 reload from

TnCRA

TnCNT1 reload from

TnCRA

TnBPND

TnCNT1 reload from

TnCRB

Input Capture on TBn

transition

N/A

Input Capture on TBn

transition

TnCPND

N/A

TnCNT1 underﬂow

N/A

Tier

Int. 2

TnDPND

TnCNT2 underﬂow

TnCNT2 reload from

TnCRB

TnCNT2 underﬂow

Reload A

Timer/Counter 1

Capture B

Timer 1

Clock

TAn

TAIEN

TAPND

TnCNT1

TnCRA

TnCRB

Timer

Interrupt 1

TATEN

Timer/Counter 2

TnCNT2

Timer 2

Clock

Underflow

TDIEN

TDPND

Timer

Interrupt 2

TBIEN

TBPND

Timer

Interrupt 1

TBn

TBEN

Preset

Figure 50. Mode 4, Input Capture and Timer

PC87591L Datasheet(PDF) 140 Page - National Semiconductor (TI)

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