MC68HC08JL8 Datasheet, PDF (113/212 Pages) Freescale Semiconductor, Inc – Microcontrollers

TIM During Break Interrupts
8.7 TIM During Break Interrupts
A break interrupt stops the TIM 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 5.7.3 Break Flag Control Register (BFCR).)
To allow software to clear status bits during a break interrupt, write a logic 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 logic 0 to the BCFE bit. With BCFE at logic 0 (its
default state), software can read and write I/O registers during the break state without affecting status bits.
Some status bits have a 2-step read/write clearing procedure. If software does the first step on such a bit
before the break, the bit cannot change during the break state as long as BCFE is at logic 0. After the
break, doing the second step clears the status bit.
8.8 I/O Signals
Port D shares two of its pins with TIM1 and port E shares two of its pins with TIM2. The ADC12/T2CLK
pin is an external clock input to TIM2. The four TIM channel I/O pins are T1CH0, T1CH1, T2CH0, and
T2CH1.
8.8.1 TIM Clock Pin (ADC12/T2CLK)
ADC12/T2CLK is an external clock input that can be the clock source for the TIM2 counter instead of the
prescaled internal bus clock. Select the ADC12/T2CLK input by writing logic 1’s to the three prescaler
select bits, PS[2:0]. (See 8.9.1 TIM Status and Control Register.) The minimum T2CLK pulse width,
T2CLK_LMIN or T2CLK_HMIN, is:
------------------1-------------------
bus frequency
+
tSU
The maximum T2CLK frequency is:
bus frequency ÷ 2
ADC12/T2CLK is available as a ADC input channel pin when not used as the TIM2 clock input.
8.8.2 TIM Channel I/O Pins (PTD4/T1CH0, PTD5/T1CH1, PTE0/T2CH0, PTE1/T2CH1)
Each channel I/O pin is programmable independently as an input capture pin or an output compare pin.
T1CH0 and T2CH0 can be configured as buffered output compare or buffered PWM pins.
MC68HC908JL8/JK8 • MC68HC08JL8/JK8 • MC68HC908KL8 Data Sheet, Rev. 3.1
Freescale Semiconductor
113