Micronas SDA 6000, User Manual

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SDA 6000
PRELIMINARY DATA SHEET
Version 2.1
Peripherals
7 - 26 Micronas
Figure 7-19 Timer Block 2 Register CAPREL in Capture-And-Reload Mode
This combined mode can be used to detect consecutive external events which may
occur aperiodically, but where a finer resolution, i.e. more ‘ticks’ within the time between
two external events, is required.
For this purpose, the time between the external operations is measured using timer T5
and the CAPREL register. Timer T5 runs in timer mode counting up with a frequency of
e.g.
f
hw_clk
/32. The external operations are applied to line CAPIN. When an external
operation occurs, the timer T5 contents are latched into register CAPREL, and timer T5
is cleared (T5CLR = ‘1’). Thus, register CAPREL always contains the correct time
between two operations, measured in timer T5 increments. Timer T6, which runs in timer
mode counting down with a frequency of e.g.
f
hw_clk
/4, uses the value in register CAPREL
to perform a reload on underflow. This means that the value in register CAPREL
represents the time between two underflows of timer T6, now measured in timer T6
increments. Since timer T6 runs 8 times faster than timer T5, it will underflow 8 times
within the time between two external operations. Thus, the underflow signal of timer T6
generates 8 ‘ticks’. Upon each underflow, the interrupt request flag T6IR will be set and
UEB11210
Auxiliary Timer T5
Up/Down
Interrupt
Request
Interrupt
Request
T5CLR
T5SC
T5CC
Edge
Select
CI
MUX
CAPREL Register
CAPIN
T3IN/
T3EUD
Input
Clock
CT3
Up/Down
Input
Clock
Core Timer T6
T6SR
Request
Interrupt
T6OFL
T6CLR