6.5 Application of the eCAP Module
The following sections will provide applications examples to show how to operate the eCAP module.
6.5.1 Example 1 - Absolute Time-Stamp Operation Rising Edge Trigger
shows an example of continuous capture operation (Mod4 counter wraps around). In this figure,
TSCTR counts-up without resetting and capture events are qualified on the rising edge only, this gives period
(and frequency) information.
On an event, the TSCTR contents (time-stamp) is first captured, then Mod4 counter is incremented to the next
state. When the TSCTR reaches FFFFFFFF (maximum value), it wraps around to 00000000 (not shown in
), if this occurs, the CTROVF (counter overflow) flag is set, and an interrupt (if enabled) occurs,
CTROVF (counter overflow) Flag is set, and an Interrupt (if enabled) occurs. Captured Time-stamps are valid at
the point indicated by the diagram (after the 4th event), hence event CEVT4 can conveniently be used to trigger
an interrupt and the CPU can read data from the CAPx registers.
CEVT1
CEVT2
CEVT3
CEVT4
CEVT1
CAPx pin
0
1
2
3
0
1
XX
t
5
XX
t
2
XX
t
3
XX
t
4
t
1
Capture registers [1−4]
All capture values valid
(can be read) at this time
00000000
FFFFFFFF
CTR[0−31]
t
1
t
2
t
3
t
4
t
5
MOD4
CTR
CAP1
CAP2
CAP3
CAP4
t
Polarity selection
Figure 6-12. Capture Sequence for Absolute Time-stamp and Rising Edge Detect
Enhanced Capture (eCAP)
442
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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