AN2281 datasheet(33/38 Pages) STMICROELECTRONICS

33 / 38 page

AN2281

List of software functions and interrupt service routines

33/38

lt.c Module

LT_TB1_IT_Routine

LT_ICAP_IT_Routine

Description:

Lite Timer counter 1 overflow interrupt service routine.

The Lite Timer is configured so that this interrupt occurs every 1 msec., two

variables are incremented in this interrupt service routine. Then "counter"

variable is used for Hall sensor signal semi-period measurement and the

"timebase_1ms" variable is used as 1 msec time base.

Input:

None

Returns:

None

Duration:

4.35µsec

Description:

Lite Timer input capture interrupt service routine.

Hall sensor signal semi-period measurement is performed in this routine.

Moreover, depending on the logical value of the Hall sensor signal, the

phase of the PWM modulated sinusoidal voltage output on pin ATPWM0

(phase C) is forced with phase angle value

Φ or with Φ+π. Finally, the

watchdog timer is enabled/refreshed so that, if no Hall sensor edges occur

in 127msec (corresponding to an electrical frequency of less than 4 Hz), a

hardware reset is generated.

Figure 22 shows the flowchart of this interrupt service routine.

Input:

None

Returns:

None

Duration:

The average duration is 26.15 µsec.

AN2281 Datasheet(PDF) 33 Page - STMicroelectronics