Freescale Semiconductor MC68HC908MR32 Manual Do Utilizador

Freescale Semiconductor

235

This section describes the timer interface module B (TIMB). The TIMB is a 2-channel timer that provides:

•

Timing reference with input capture

•

Output compare

•

Pulse-width modulation functions 

 is a block diagram of the TIMB.

Features of the TIMB include:

•

Two input capture/output compare channels:
–

Rising-edge, falling-edge, or any-edge input capture trigger

–

Set, clear, or toggle output compare action

•

Buffered and unbuffered pulse-width modulation (PWM) signal generation

•

Programmable TIMB clock input:
–

7-frequency internal bus clock prescaler selection

–

External TIMB clock input (4-MHz maximum frequency)

•

Free-running or modulo up-count operation

•

Toggle any channel pin on overflow

•

TIMB counter stop and reset bits

 shows the TIMB structure. The central component of the TIMB is the 16-bit TIMB counter that 

can operate as a free-running counter or a modulo up-counter. The TIMB counter provides the timing 
reference for the input capture and output compare functions. The TIMB counter modulo registers, 
TBMODH–TBMODL, control the modulo value of the TIMB counter. Software can read the TIMB counter 
value at any time without affecting the counting sequence.

The two TIMB channels are programmable independently as input capture or output compare channels.