MC68HC08AS20 Datasheet, PDF (218/386 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

TRST — TIM Reset Bit
Setting this write-only bit resets the TIM counter and the TIM
prescaler. Setting TRST has no effect on any other registers.
Counting resumes from $0000. TRST is cleared automatically after
the TIM counter is reset and always reads as logic 0. Reset clears the
TRST bit.
1 = Prescaler and TIM counter cleared
0 = No effect
NOTE: Setting the TSTOP and TRST bits simultaneously stops the TIM counter
at a value of $0000.
PS[2–0] — Prescaler Select Bits
These read/write bits select either the PTD6/ATD14/TCLK pin or one
of the seven prescaler outputs as the input to the TIM counter as
Table 16-2 shows. Reset clears the PS[2–0] bits.
PS[2–0]
000
001
010
011
100
101
110
111
Table 16-2. Prescaler Selection
TIM Clock Source
Internal Bus Clock ÷1
Internal Bus Clock ÷ 2
Internal Bus Clock ÷ 4
Internal Bus Clock ÷ 8
Internal Bus Clock ÷ 16
Internal Bus Clock ÷ 32
Internal Bus Clock ÷ 64
PTD6/ATD14/TCLK
Advance Information
218
MC68HC08AS20 —Rev. 4.1
Freescale Semiconductor