Introduction

ECAP Capture Mode

ECAP runs at 200 MHz and timestamps the edges (rising and/or falling) into 4 Capture registers. This example reads a PWM wave and determines its frequency and duty cycle. Configuring the input via GPI and InputXbar into the ECAP for Falling, Rising, Falling, Rising

INPUT
                _________           _________           _________
                |       |           |       |           |
        ________|       |___________|       |___________|
                        ^           ^       ^           ^
EDGE EVENT             1.F         2.R     3.F         4.R
DATA            <--NA--><-OFF time-><--ON--><-OFF time->

ECAP will be configured to reset counter on each edge recieved, and capture for one shot. So the timestamp registers hold the data as follows

OFF time
ON time
OFF time

This example uses the ECAP in capture mode to capture PWM.

The example does the below

Configures ECAP in Capture mode and captures the epwm output.
It captures the time between the rising and falling edge of epwm output.

___________________          _____________             __________________
|                 |          |           |             |                |
|      EPWM       |---GPIO---| I/P XBAR  |---I/P MUX---|     ECAP       |---INT XBAR
|_________________|          |___________|             |________________|

External Connections

AM263X-CC or AM263PX-CC

No external connection is required.

AM263X-LP or AM263PX-LP

No external connection is required.

Supported Combinations

Parameter	Value
CPU + OS	r5fss0-0 nortos
Toolchain	ti-arm-clang
Boards	am263x-cc, am263x-lp
Example folder	examples/drivers/ecap/ecap_capture_pwm/

Steps to Run the Example

When using CCS projects to build, import the CCS project for the required combination and build it using the CCS project menu (see Using SDK with CCS Projects).
When using makefiles to build, note the required combination and build using make command (see Using SDK with Makefiles)
Establish connections as mentioned in External Connections section
Launch a CCS debug session and run the executable, see CCS Launch, Load and Run

Sample Output

Shown below is a sample output when the application is run,

ECAP Capture Pwm Test Started ...
Period : 10010 ns
Duty : 0.500000
frequency : 99.900101 Hz
Period : 10030 ns
Duty : 0.500000
frequency : 99.700897 Hz
Period : 10050 ns
Duty : 0.500000
frequency : 99.502487 Hz
Period : 10070 ns
Duty : 0.500000
frequency : 99.304863 Hz
Period : 10090 ns
Duty : 0.500000
frequency : 99.108025 Hz
Period : 10110 ns
Duty : 0.500000
frequency : 98.911972 Hz
Period : 10130 ns
Duty : 0.500000
frequency : 98.716682 Hz
Period : 10150 ns
Duty : 0.500000
frequency : 98.522171 Hz
Period : 10170 ns
Duty : 0.500000
frequency : 98.328415 Hz
Period : 10190 ns
Duty : 0.500000
frequency : 98.135429 Hz
Interrupt No.: 10 and Pass Count: 10
ECAP Capture Pwm Passed!!
All tests have passed!!

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