Texas Instruments TMS320F2837 D Series Workshop Guide And Lab Manual

eCAP
7 - 46 TMS320F2837xD Microcontroller Workshop - Control Peripherals
eCAP Interrupt Enable Register
ECapxRegs.ECEINT
CTR=CMP CTR=PRD
7 3 02
CTROVF CEVT4 CEVT3 CEVT2 CEVT1
1456
reserved
15 - 8
reserved
0 = disable as interrupt source
1 = enable as interrupt source
CTR = CMP
Interrupt Enable
CTR = PRD
Interrupt Enable
CTR = Overflow
Interrupt Enable
Capture Event 3
Interrupt Enable
Capture Event 1
Interrupt Enable
Capture Event 4
Interrupt Enable
Capture Event 2
Interrupt Enable
The capture unit interrupts offer immediate CPU notification of externally captured events. In
situations where this is not required, the interrupts can be masked and flag testing/polling can be
used instead. This offers increased flexibility for resource management. For example, consider a
servo application where a capture unit is being used for low-speed velocity estimation via a
pulsing sensor. The velocity estimate is not used until the next control law calculation is made,
which is driven in real-time using a timer interrupt. Upon entering the timer interrupt service
routine, software can test the capture interrupt flag bit. If sufficient servo motion has occurred
since the last control law calculation, the capture interrupt flag will be set and software can
proceed to compute a new velocity estimate. If the flag is not set, then sufficient motion has not
occurred and some alternate action would be taken for updating the velocity estimate. As a
second example, consider the case where two successive captures are needed before a
computation proceeds (e.g. measuring the width of a pulse). If the width of the pulse is needed
as soon as the pulse ends, then the capture interrupt is the best option. However, the capture
interrupt will occur after each of the two captures, the first of which will waste a small number of
cycles while the CPU is interrupted and then determines that it is indeed only the first capture. If
the width of the pulse is not needed as soon as the pulse ends, the CPU can check, as needed,
the capture registers to see if two captures have occurred, and proceed from there.

Texas Instruments TMS320F2837 D Series Specifications

General

Brand	Texas Instruments
Model	TMS320F2837 D Series
Category	Microcontrollers
Language	English