Timer Interface A (TIMA)
I/O Signals
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Timer Interface A (TIMA) 213
If TIMA functions are not required during wait mode, reduce power
consumption by stopping the TIMA before executing the WAIT
instruction.
11.7 I/O Signals
Port E shares five of its pins with the TIMA:
PTE3/TCLKA is an external clock input to the TIMA prescaler.
The four TIMA channel I/O pins are PTE4/TCH0A, PTE5/TCH1A,
PTE6/TCH2A, and PTE7/TCH3A.
11.7.1 TIMA Clock Pin (PTE3/TCLKA)
PTE3/TCLKA is an external clock input that can be th e cl o ck sou r ce f or
the TIMA counter instead of the prescaled internal bus clock. Select the
PTE3/TCLKA input by writing logic 1s to the three prescaler select bits,
PS[2:0]. See 11.8.1 TIMA Status and Control Register. The minimum
TCLK pulse width, TCLKLMIN or TCLKHMIN, is:
The maximum TCLK frequency is the least: 4 MHz or bu s frequency ÷ 2.
PTE3/TCLKA is available as a gener al-purpo se I/O p in or ADC channe l
when not used as the TIMA clock input. When the PTE3/TCLKA pin is
the TIMA clock input, it is an input regardless of the state of the DDRE3
bit in data direction register E.
11.7.2 TIMA Channel I/O Pins (PTE4/TCH0A–PTE7/TCH3A)
Each channel I/O pin is programmable independently as an input
capture pin or an output compare pin . PTE2/TCH 0 and PTE4/TCH2 can
be configured as buffered output compare or buffered PWM pins.
1
bus frequency
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