Motorola M68HC08 Reference Manual page 158

User Guide
6.5.7.3 Current Sampling Instant
6.5.8 Conclusion Software Parameters Setting and Tuning
Designer Reference Manual
158
Freescale Semiconductor, Inc.
For current sampling period setting follow the label
CAN_CHANGE_PERCURSAMP_n in const.h file.
Current sampling period setting is provided by:
/* CAN_CHANGE_FPWM_n: */
/* CAN_CHANGE_PERCURSAMP_n: */
#define SET_PER_CS
Range: <1,->
The final current sampling period [ s] is:
Current sampling period
current sampling period = PWM period * SET_PER_CS [ s]
PER_CS_T1_US = PERIOD_PWM_US * SET_PER_CS [ s]
Time period from a PWM reload event (middle of central aligned PWM)
to current sampling (time shift of A/D conversion with PWM) [ s]:
/* CAN_CHANGE_PERCURSAMP_n: */
#define PER_PWM_CS_US
Range: <-PERIOD_PWM_US/2,PERIOD_PWM_US/2>
Usually it is not recommended to change PER_PWM_CS_US, but it can
be evaluated when there are problems with back-EMF zero crossing
noise.
It is necessary to set SET_PER_CS according to the following equation:
PERIOD_PWM_US
--------------------------------------------------- -
– <
2
If all the points in Tuning for Customer Motor
should be customized to customer motor.
If the software customizing of your motor was not successful, it is
recommended that you read
User Guide
For More Information On This Product,
Go to: www.freescale.com
2.0
= PWM period*SET_PER_CS
5.0
PERIOD_PWM_US
PER_PWM_CS_US < --------------------------------------------------- -
Application Suitability
(EQ 6-16.)
2
(EQ 6-17.)
are done, the software
Guide, since the
DRM028 — Rev 0
MOTOROLA