AN1661 Freescale Semiconductor / Motorola, AN1661 Datasheet - Page 10

• Manufacturer Part Number: AN1661
• Description: Low Cost Universal Motor Chopper Drive System
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
Watchdog
Subroutine
Interrupts
10
ENABLE 6X IC
TIMER OVERFLOW
INTERRUPT
START A/D
The watchdog subroutine is entered when the watchdog register has not
been updated for approximately 4 seconds. The input capture interrupt
service routine, as a result of the running motor, takes the responsibility
for the watchdog register. By this arrangement, it is possible to protect
the motor when the shaft is blocked. In this case, the watchdog will turn
off the IGBT and will wait for a new START command.
In this application, the MCU can be interrupted in these two different
ways:
•
•
Freescale Semiconductor, Inc.
RTI
Figure 7. Interrupt Service Routines
For More Information On This Product,
The simplest interrupt is the timer overflow interrupt. The
appropriate service routine is the timer overflow interrupt service
routine (TOISR), and it enables the input capture interrupt and
starts the A/D convertor.
The input capture interrupt service routine (ICISR) is allowed to
run six times every 87 ms (TOISR occurred), and it calculates an
average value of the time interval between the rising edges of the
tachometer signal.
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RUN APPLICATION
INPUT CAPTURE
INTERRUPT
SENSE TACHO SIGNAL
RTI
MOTOROLA
AN1661