mc68hc908qz16 Freescale Semiconductor, Inc, mc68hc908qz16 Datasheet - Page 263

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mc68hc908qz16

Manufacturer Part Number
mc68hc908qz16
Description
M68hc08 Microcontrollers
Manufacturer
Freescale Semiconductor, Inc
Datasheet
Setting MS0B links channels 0 and 1 and configures them for buffered PWM operation. The TIM
channel 0 registers (TCH0H:TCH0L) initially control the buffered PWM output. TIM status control
register 0 (TSCR0) controls and monitors the PWM signal from the linked channels.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM overflows. Subsequent output
compares try to force the output to a state it is already in and have no effect. The result is a 0% duty cycle
output.
Setting the channel x maximum duty cycle bit (CHxMAX) and setting the TOVx bit generates a 100% duty
cycle output. See
19.5 Interrupts
The following TIM sources can generate interrupt requests:
19.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power- consumption standby modes.
19.6.1 Wait Mode
The TIM remains active after the execution of a WAIT instruction. In wait mode, the TIM registers are not
accessible by the CPU. Any enabled CPU interrupt request from the TIM can bring the MCU out of wait
mode.
Freescale Semiconductor
4. In TIM channel x status and control register (TSCx):
5. In the TIM status control register (TSC), clear the TIM stop bit, TSTOP.
TIM overflow flag (TOF) — The TOF bit is set when the TIM counter reaches the modulo value
programmed in the TIM counter modulo registers. The TIM overflow interrupt enable bit, TOIE,
enables TIM overflow CPU interrupt requests. TOF and TOIE are in the TIM status and control
register.
TIM channel flags (CH1F:CH0F) — The CHxF bit is set when an input capture or output compare
occurs on channel x. Channel x TIM CPU interrupt requests are controlled by the channel x
interrupt enable bit, CHxIE. Channel x TIM CPU interrupt requests are enabled when CHxIE = 1.
CHxF and CHxIE are in the TIM channel x status and control register.
a. Write 0:1 (for unbuffered output compare or PWM signals) or 1:0 (for buffered output compare
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (to clear output on compare) or 1:1 (to set output on compare) to the edge/level
or PWM signals) to the mode select bits, MSxB:MSxA. See
select bits, ELSxB:ELSxA. The output action on compare must force the output to the
complement of the pulse width level. See
In PWM signal generation, do not program the PWM channel to toggle on
output compare. Toggling on output compare prevents reliable 0% duty
cycle generation and removes the ability of the channel to self-correct in the
event of software error or noise. Toggling on output compare can also
cause incorrect PWM signal generation when changing the PWM pulse
width to a new, much larger value.
19.9.4 TIM Channel Status and Control
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
NOTE
Table
Registers.
19-3.
Table
19-3.
Interrupts
263

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