mc68hc908ap8cfa Freescale Semiconductor, Inc, mc68hc908ap8cfa Datasheet - Page 151

• Manufacturer Part Number: mc68hc908ap8cfa
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 10
Timebase Module (TBM)
10.1 Introduction
This section describes the timebase module (TBM). The TBM will generate periodic interrupts at user
selectable rates using a counter clocked by the selected OSCCLK clock from the oscillator module. This
TBM version uses 18 divider stages, eight of which are user selectable.
10.2 Features
Features of the TBM module include:
10.3 Functional Description
This module can generate a periodic interrupt by dividing the oscillator clock frequency, OSCCLK. The
counter is initialized to all 0s when TBON bit is cleared. The counter, shown in
when the TBON bit is set. When the counter overflows at the tap selected by TBR[2:0], the TBIF bit gets
set. If the TBIE bit is set, an interrupt request is sent to the CPU. The TBIF flag is cleared by writing a 1
to the TACK bit. The first time the TBIF flag is set after enabling the timebase module, the interrupt is
generated at approximately half of the overflow period. Subsequent events occur at the exact period.
The reference clock OSCCLK is derived from the oscillator module, see
Selection.
Freescale Semiconductor
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Software programmable 8s, 4s, 2s, 1s, 2ms, 1ms, 0.5ms, and 0.25ms periodic interrupt using
32.768-kHz OSCCLK clock
User selectable oscillator clock source enable during stop mode to allow periodic wake-up from
stop
MC68HC908AP Family Data Sheet, Rev. 4
5.2.2 TBM Reference Clock
Figure
10-1, starts counting
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