MC68HC908AZ32ACFU MOTOROLA [Motorola, Inc], MC68HC908AZ32ACFU Datasheet - Page 283

• Manufacturer Part Number: MC68HC908AZ32ACFU
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

18.4 Functional Description
18.4.1 TIMA Counter Prescaler
18.4.2 Input Capture
68HC908AZ32A — Rev 0.0
MOTOROLA
Figure 18-1
TIMA is the 16-bit TIMA counter that can operate as a free-running
counter or a modulo up-counter. The TIMA counter provides the timing
reference for the input capture and output compare functions. The TIMA
counter modulo registers, TAMODH–TAMODL, control the modulo
value of the TIMA counter. Software can read the TIMA counter value at
any time without affecting the counting sequence.
The six TIMA channels are programmable independently as input
capture or output compare channels.
The TIMA clock source can be one of the seven prescaler outputs or the
TIMA clock pin, PTD6/ATD14/TCLK. The prescaler generates seven
clock rates from the internal bus clock. The prescaler select bits, PS[2:0],
in the TIMA status and control register select the TIMA clock source.
An input capture function has three basic parts: edge select logic, an
input capture latch and a 16-bit counter. Two 8-bit registers, which make
up the 16-bit input capture register, are used to latch the value of the
free-running counter after the corresponding input capture edge detector
senses a defined transition. The polarity of the active edge is
programmable. The level transition which triggers the counter transfer is
defined by the corresponding input edge bits (ELSxB and ELSxA in
TASC0 through TASC5 control registers with x referring to the active
channel number). When an active edge occurs on the pin of an input
capture channel, the TIMA latches the contents of the TIMA counter into
the TIMA channel registers, TACHxH–TACHxL. Input captures can
generate TIMA CPU interrupt requests. Software can determine that an
input capture event has occurred by enabling input capture interrupts or
by polling the status flag bit.
Freescale Semiconductor, Inc.
For More Information On This Product,
Timer Interface Module A (TIMA)
shows the TIMA structure. The central component of the
Go to: www.freescale.com
Timer Interface Module A (TIMA)
Functional Description
Advance Information
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