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Motorola M68HC08 User Manual

Page 107

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Software Design

Implementation Notes

DRM028 — Rev 0

Designer Reference Manual

MOTOROLA

Software Design

107

The value T2 (e.g., T2 = T_Cmt + Per_HlfCmt) is calculated using
a 16-bit addition with no saturation. So, the time duration up to
65,536 UNIT_PERIOD_T2_US from actual time (TACNTH,
TACNTL) can be timed at any TACNTH, TACNTL timer A counter
value.

The timer unit UNIT_PERIOD_T2_US of timer A is determined by
the MCU bus frequency (8 MHz with 4-MHz oscillator and default
software setting) and timer prescaler set in TASC. So, the default
software value is 2

µs. The timer 2 interrupt function is provided by

function TIMACh3_Int().

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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