MC68HC901 Datasheet, PDF (60/73 Pages) Motorola, Inc – Multi-Function Peripheral

Electrical Characteristics
8.8 TIMER AC CHARACTERISTICS
Definitions:
Error = Indicated time value – actual time value
t_psc = t_CLK x Prescale Value
Internal Timer Mode:
Single Interval Error (Free Running) (See Note 2 below) . . . . . . . . . . . . . . . . ±100 ns
Cumulative Internal Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0
Error Between Two Timer Reads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± (t_psc – 4 t_CLK)
Start Timer to Stop Timer Error . . . . . . . . 2 t_CLK + 100 ns to – (t_psc + 6 t_CLK + 100 ns)
Start Timer to Read Timer Error . . . . . . . . . . . . . . . . . . . 0 to – (t_psc + 6 t_CLK + 400 ns)
Start Timer to Interrupt Request Error
(See Note 3 below) . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 2 t_CLK to – (4 t_CLK + 800 ns)
Pulse Width Measurement Mode:
Measurement Accuracy (See Note 1 below) . . . . . . . . . . . . 2 t_CLK to – (t_psc + 4 t_CLK)
Minimum Pulse Width. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 t_CLK
Event Counter Mode:
Minimum Active Time of TAI and TBI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 t_CLK
Minimum Inactive Time of AI and TBI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 t_CLK
NOTES: 1.
2.
3.
Error may be cumulative if repetitively performed.
Error with respect to tout or IRQ if note 3 is true.
Assuming it is possible for the timer to make an interrupt request immediately.
8-7
MC68HC901 USER’S MANUAL
MOTOROLA