MC68HC908AS32A Datasheet, PDF (236/280 Pages) Freescale Semiconductor, Inc – Microcontrollers

Timer Interface Module (TIM)
break, the bit cannot change during the break state as long as BCFE is at 0. After the break, doing the
second step clears the status bit.
17.7 I/O Signals
Port D shares one of its pins with the TIM. Port E shares two of its pins with the TIM and port F shares
four of its pins with the TIM. PTD6/ATD14/TCLK is an external clock input to the TIM prescaler. The six
TIM channel I/O pins are PTE2/TCH0, PTE3/TCH1, PTF0/TCH2, PTF1/TCH3, PTF2/TCH4, and
PTF3/TCH5.
17.7.1 TIM Clock Pin (PTD6/ATD14/TCLK)
PTD6/ATD14/TCLK is an external clock input that can be the clock source for the TIM counter instead of
the prescaled internal bus clock. Select the PTD6/ATD14/TCLK input by writing 1s to the three prescaler
select bits, PS[2:0] (see 17.8.1 TIM Status and Control Register). The minimum TCLK pulse width,
TCLK_LMIN or TCLK_HMIN, is:
------------------1-------------------
bus frequency
+
t_SU
The maximum TCLK frequency is the least: 4 MHz or bus frequency ÷ 2.
PTD6/ATD14/TCLK is available as a general-purpose I/O pin or ADC channel when not used as the TIM
clock input. When the PTD6/ATD14/TCLK pin is the TIM clock input, it is an input regardless of the state
of the DDRD6 bit in data direction register D.
17.7.2 TIM Channel I/O Pins (PTF3/TCH5–PTF0/TCH2 and PTE3/TCH1–PTE2/TCH0)
Each channel I/O pin is programmable independently as an input capture pin or an output compare pin.
PTE2/TCH0, PTF0/TCH2, and PTF2/TCH4 can be configured as buffered output compare or buffered
PWM pins.
17.8 I/O Registers
These I/O registers control and monitor TIM operation:
• TIM status and control register (TSC)
• TIM control registers (TCNTH–TCNTL)
• TIM counter modulo registers (TMODH–TMODL)
• TIM channel status and control registers (TSC0–TSC5)
• TIM channel registers (TCH0H–TCH0L through TCH5H–TCH5L)
17.8.1 TIM Status and Control Register
The TIM status and control register:
• Enables TIM overflow interrupts
• Flags TIM overflows
• Stops the TIM counter
• Resets the TIM counter
• Prescales the TIM counter clock
MC68HC908AS32A Data Sheet, Rev. 2.0
236
Freescale Semiconductor