MC68HC08GZ32 Datasheet, PDF (248/320 Pages) Freescale Semiconductor, Inc – Microcontrollers

Timer Interface Module (TIM1)
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.
5. In the TIM1 status control register (T1SC), clear the TIM1 stop bit, TSTOP.
Setting MS0B links channels 0 and 1 and configures them for buffered PWM operation. The TIM1 channel
0 registers (TCH0H:TCH0L) initially control the buffered PWM output. TIM1 status control register 0
(TSCR0) controls and monitors the PWM signal from the linked channels. MS0B takes priority over MS0A.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM1 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 18.9.4 TIM1 Channel Status and Control Registers.
18.5 Interrupts
The following TIM1 sources can generate interrupt requests:
• TIM1 overflow flag (TOF) — The TOF bit is set when the TIM1 counter reaches the modulo value
programmed in the TIM1 counter modulo registers. The TIM1 overflow interrupt enable bit, TOIE,
enables TIM1 overflow CPU interrupt requests. TOF and TOIE are in the TIM1 status and control
register.
• TIM1 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 TIM1 channel x status and control register.
18.6 Wait Mode
The WAIT instruction puts the MCU in low power-consumption standby mode.
The TIM1 remains active after the execution of a WAIT instruction. In wait mode the TIM1 registers are
not accessible by the CPU. Any enabled CPU interrupt request from the TIM1 can bring the MCU out of
wait mode.
If TIM1 functions are not required during wait mode, reduce power consumption by stopping the TIM1
before executing the WAIT instruction.
18.7 TIM1 During Break Interrupts
A break interrupt stops the TIM1 counter.
The system integration module (SIM) controls whether status bits in other modules can be cleared during
the break state. The BCFE bit in the break flag control register (BFCR) enables software to clear status
bits during the break state. See 20.2.2.4 Break Flag Control Register.
To allow software to clear status bits during a break interrupt, write a 1 to the BCFE bit. If a status bit is
cleared during the break state, it remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a 0 to the BCFE bit. With BCFE at 0 (its default state),
software can read and write I/O registers during the break state without affecting status bits. Some status
MC68HC08GZ32 Data Sheet, Rev. 3
248
Freescale Semiconductor