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Freescale Semiconductor, Inc.
Software Design
Software Implementation
PMOD = 0x00e6;
DEADTM=15;
Freescale Semiconductor, Inc...
DISMAP=0xff;
PCTL2 = 0x80;
PCTL1 |= 0xc0;
PWMOUT = 0x00;
PCTL1 |= 0x02;
FCR |= 0x08;
/* set up PWM modulus => PWM frequency */
/* for 7.3728MHz Bus Frequency
PWM_MODULUS = 0x00e6 gives 16kHz PWM */
/* 2usec deadtime = #15
(for Bus freq. = 7.3728MHz) */
/* when PWM disabled, disable PWM1-6 */
/* PWM interrupt every 4th. PWM loads */
/* disable MCPWM */
/* output port control is PWM gen. */
/* set LDOK bit */
/* Flt2 enabled in manual mode */
PVAL1 = PWM_MODULUS/2; /* set phase A pwm to 50% */
PVAL3 = PWM_MODULUS/2; /* set phase B pwm to 50% */
PVAL5 = PWM_MODULUS/2; /* set phase C pwm to 50% */
When all modules of the microcontroller are initialised, enable the PWM
module:
PCTL1 |= 0x20;
PCTL1 |= 0x01;
/* enables PWM interrupts */
/* enables PWM */
4.4.2 Software Timer
The software timer routine provides the timing sequence for required
subroutines. The software timer is performed instead of an Output
Capture interrupt handler because of lack of interrupt priority in the HC08
MCU. The main program has several time-demanding interrupt routines
and more interrupt requirements can cause a software fault.
The software timer routine has two timed outputs •
in READ_CONST timeout, there is a routine that scans inputs,
calculates speed command, handles fault routines and the LED
driver
DRM020 — Rev 0
MOTOROLA
Designer Reference Manual
Software Design
For More Information On This Product,
Go to: www.freescale.com
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