Datasheet

channel (n) input
(after the filter
DECAPEN bit
C(n+1)VH:L
FTM counter
clear CH(n+1)F
2
1
2
3
channel input)
DECAP bit
set DECAPEN
set DECAP
5
6
7
8
10
3
4
6
5
Note
- The commands set DECAPEN, set DECAP, clear CH(n)F, and clear CH(n+1)F are made by the user.
4
9
11
12
13
14
9
10
7
15
16
17
18
19
20
21
22
23
24
25
26
27
28
15
16
20
C(n)VH:L
CH(n+1)F bit
CH(n)F bit
clear CH(n)F
1
8
12
22 24
11
19
21
23
Figure 12-255. Dual edge capture – continuous mode for positive polarity pulse width
measurement
12.4.21.4 Period measurement
If the channels (n) and (n+1) are configured to capture consecutive edges of the same
polarity, then the period of the channel (n) input signal is measured. If both channels (n)
and (n+1) are configured to capture rising edges (ELS(n)B:ELS(n)A = 0:1 and ELS(n
+1)B:ELS(n+1)A = 0:1), then the period between two consecutive rising edges is
measured. If both channels (n) and (n+1) are configured to capture falling edges
(ELS(n)B:ELS(n)A = 1:0 and ELS(n+1)B:ELS(n+1)A = 1:0), then the period between
two consecutive rising edges is measured.
The period measurement can be made in one-shot capture mode (One-shot capture mode)
or continuous capture mode (Continuous capture mode).
The following figure shows an example of the dual edge capture – one-shot mode used to
measure the period between two consecutive rising edges. The DECAPEN bit selects the
dual edge capture mode, so it keeps set in all operation mode. The DECAP bit is set to
Functional Description
MC9S08PA60 Reference Manual, Rev. 1, 9/2012
376 Freescale Semiconductor, Inc.