Information

channel (n) input
(after the filter
DECAPEN bit
C(n+1)V
FTM counter
clear CH(n+1)F
problem 1 problem 2
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
8
15
16
17
18
19
20
21
22
23
24
25
26
27
28
15
16
19
20
22
24
- Problem 1: channel (n) input = 1, set DECAP, not clear CH(n)F, and clear CH(n+1)F.
- Problem 2: channel (n) input = 1, set DECAP, not clear CH(n)F, and not clear CH(n+1)F.
C(n)V
CH(n+1)F bit
CH(n)F bit
clear CH(n)F
1
Figure 35-204. Dual Edge Capture – One-Shot mode for positive polarity pulse width
measurement
The following figure shows an example of the Dual Edge Capture – Continuous mode
used to measure the positive polarity pulse width. The DECAPEN bit selects the Dual
Edge Capture mode, so it remains set. While the DECAP bit is set the configured
measurements are made. The CH(n)F bit is set when the first edge of the positive polarity
pulse is detected, that is, the edge selected by ELS(n)B:ELS(n)A bits. The CH(n+1)F bit
is set when the second edge of this pulse is detected, that is, the edge selected by ELS(n
+1)B:ELS(n+1)A bits. The CH(n+1)F bit indicates when two edges of the pulse were
captured and the C(n)V and C(n+1)V registers are ready for reading.
Chapter 35 FlexTimer Module (FTM)
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 801