16.6 I/O Signals

I/O Signals

The TIMA remains active after the execution of a WAIT instruction. In wait mode, the TIMA registers are not accessible by the CPU. Any enabled CPU interrupt request from the TIMA can bring the MCU out of wait mode.

If TIMA functions are not required during wait mode, reduce power consumption by stopping the TIMA before executing the WAIT instruction.

Port E shares five of its pins with the TIMA:

•PTE3/TCLKA is an external clock input to the TIMA prescaler.

•The four TIMA channel I/O pins are PTE4/TCH0A, PTE5/TCH1A, PTE6/TCH2A, and PTE7/TCH3A.

16.6.1 TIMA Clock Pin (PTE3/TCLKA)

PTE3/TCLKA is an external clock input that can be the clock source for the TIMA counter instead of the prescaled internal bus clock. Select the PTE3/TCLKA input by writing logic 1s to the three prescaler select bits, PS[2:0]. See 16.7.1 TIMA Status and Control Register.

The maximum TCLK frequency is the least: 4 MHz or bus frequency ⎟ 2.

PTE3/TCLKA is available as a general-purpose I/O pin when not used as the TIMA clock input. When the PTE3/TCLKA pin is the TIMA clock input, it is an input regardless of the state of the DDRE3 bit in data direction register E.

16.6.2 TIMA Channel I/O Pins (PTE4/TCH0A–PTE7/TCH3A)

Each channel I/O pin is programmable independently as an input capture pin or an output compare pin. PTE2/TCH0 and PTE4/TCH2 can be configured as buffered output compare or buffered PWM pins.

16.7 I/O Registers

These input/output (I/O) registers control and monitor TIMA operation:

•TIMA status and control register (TASC)

•TIMA control registers (TACNTH–TACNTL)

•TIMA counter modulo registers (TAMODH–TAMODL)

•TIMA channel status and control registers (TASC0, TASC1, TASC2, and TASC3)

•TIMA channel registers (TACH0H–TACH0L, TACH1H–TACH1L, TACH2H–TACH2L, and TACH3H–TACH3L)

16.7.1 TIMA Status and Control Register

The TIMA status and control register:

•Enables TIMA overflow interrupts

•Flags TIMA overflows

•Stops the TIMA counter

•Resets the TIMA counter

•Prescales the TIMA counter clock

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

Freescale Semiconductor

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MC68HC908MR16, MC68HC908MR32 specifications

Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are part of the popular HC08 family, designed primarily for embedded applications. These microcontrollers are particularly favored in automotive, industrial, and consumer product sectors due to their reliability and versatility.

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Freescale Semiconductor MC68HC908MR16, MC68HC908MR32 manual 16.6 I/O Signals, 16.7 I/O Registers

Models: MC68HC908MR16 MC68HC908MR32