LEDC: Add examples/ledc_check.c for check freq and duty (Issue report). (IDFGH-14067)

[IhorNehrutsa]

The ledc_timer_config() does not set the right frequencies.
The ledc_channel_config() does not set the right duties.

Tested in v5.2.2 and v5.3.1
Issue report:
Freq 1, 2, 3, and 4 are wrong.
Duty on freq 80, 200, ... 5000, 10000, 40000000 are wrong.

freq=1     500.00% timer.freq_hz=1, get_freq=6,      0.00% channel.duty=524288, get_duty=524288    timer.duty_resolution=20
freq=2     500.00% timer.freq_hz=2, get_freq=12,     0.00% channel.duty=524288, get_duty=524288    timer.duty_resolution=20
freq=3     166.67% timer.freq_hz=3, get_freq=8,      0.00% channel.duty=524288, get_duty=524288    timer.duty_resolution=20
freq=4     525.00% timer.freq_hz=4, get_freq=25,     0.00% channel.duty=524288, get_duty=524288    timer.duty_resolution=20
freq=5  
freq=70  
freq=80    0.00% timer.freq_hz=80, get_freq=80,      100.00% channel.duty=262144, get_duty=524288  timer.duty_resolution=19
freq=90  
freq=100  
freq=200   0.00% timer.freq_hz=200, get_freq=200,    100.00% channel.duty=131072, get_duty=262144  timer.duty_resolution=18
freq=300  
freq=400   0.00% timer.freq_hz=400, get_freq=400,    100.00% channel.duty=65536, get_duty=131072   timer.duty_resolution=17
freq=500  
freq=600  
freq=700   0.14% timer.freq_hz=700, get_freq=701,    100.00% channel.duty=32768, get_duty=65536    timer.duty_resolution=16
freq=800  
freq=1000  
freq=2000  0.15% timer.freq_hz=2000, get_freq=1997,  100.00% channel.duty=16384, get_duty=32768    timer.duty_resolution=15
freq=3000  0.07% timer.freq_hz=3000, get_freq=2998,  100.00% channel.duty=8192, get_duty=16384    timer.duty_resolution=14
freq=4000  
freq=5000  0.00% timer.freq_hz=5000, get_freq=5000,  100.00% channel.duty=4096, get_duty=8192    timer.duty_resolution=13
freq=6000  
freq=9000  
freq=10000  0.00% timer.freq_hz=10000, get_freq=10000, 100.00% channel.duty=2048, get_duty=4096    timer.duty_resolution=12
freq=20000  
freq=30000000  
freq=40000000  0.00% timer.freq_hz=40000000, get_freq=40000000, 200.00% channel.duty=1, get_duty=3    timer.duty_resolution=1
END.

[github-actions]

Warnings

⚠️

Some issues found for the commit messages in this PR: the commit message "examples/ledc_check.c: Check freq and duty.": summary should not end with a period (full stop) summary looks empty type/action looks empty Please fix these commit messages - here are some basic tips: follow Conventional Commits style correct format of commit message should be: <type/action>(<scope/component>): <summary>, for example fix(esp32): Fixed startup timeout issue allowed types are: change,ci,docs,feat,fix,refactor,remove,revert,test sufficiently descriptive message summary should be between 20 to 72 characters and start with upper case letter avoid Jira references in commit messages (unavailable/irrelevant for our customers) TIP: Install pre-commit hooks and run this check when committing (uses the Conventional Precommit Linter).

👋 Hello IhorNehrutsa, we appreciate your contribution to this project!

---

📘 Please review the project's Contributions Guide for key guidelines on code, documentation, testing, and more.

---

🖊️ Please also make sure you have read and signed the Contributor License Agreement for this project.

---

Click to see more instructions ...

This automated output is generated by the PR linter DangerJS, which checks if your Pull Request meets the project's requirements and helps you fix potential issues.

DangerJS is triggered with each push event to a Pull Request and modify the contents of this comment.

Please consider the following:
- Danger mainly focuses on the PR structure and formatting and can't understand the meaning behind your code or changes.
- Danger is not a substitute for human code reviews; it's still important to request a code review from your colleagues.
- Resolve all warnings (⚠️ ) before requesting a review from human reviewers - they will appreciate it.
- To manually retry these Danger checks, please navigate to the Actions tab and re-run last Danger workflow.

Review and merge process you can expect ...

We do welcome contributions in the form of bug reports, feature requests and pull requests via this public GitHub repository.

This GitHub project is public mirror of our internal git repository

1. An internal issue has been created for the PR, we assign it to the relevant engineer.
2. They review the PR and either approve it or ask you for changes or clarifications.
3. Once the GitHub PR is approved, we synchronize it into our internal git repository.
4. In the internal git repository we do the final review, collect approvals from core owners and make sure all the automated tests are passing.
- At this point we may do some adjustments to the proposed change, or extend it by adding tests or documentation.
5. If the change is approved and passes the tests it is merged into the default branch.
5. On next sync from the internal git repository merged change will appear in this public GitHub repository.

Generated by 🚫 dangerJS against dd1b892

[IhorNehrutsa]

For testing ledc_timer_set(timer.speed_mode, timer.timer_num, divider, timer.duty_resolution, timer.clk_cfg)) function
you need
Add LEDC ledc_calculate_divisor() function to the /driver/ledc.h. #14884

[songruo]

ledc_timer_config() does set the right frequency, and ledc_channel_config() does set the right duty to the PWM signal.

ledc_get_freq() sometimes return wrong frequencies is because there is a calculation overflow in the function, the fix is on the way.

ledc_get_duty() sometimes return wrong duty value is because the moment you call the function is too close to the timer configuration. The internal timer hasn't reach the timer overflow moment, so the duty read register hasn't get updated yet.

The last set of configuration (40MHz) does have a bit error on the duty read on old targets (esp32 etc.). The issue does not exist anymore for chips since esp32c6. We are still trying to figure it out.

[songruo]

The last set of configuration (40MHz) does have a bit error on the duty read on old targets (esp32 etc.). The issue does not exist anymore for chips since esp32c6. We are still trying to figure it out.

FYI, we confirmed that it is a hardware issue, and there is no software workaround for it. Later, the bug details will be officially documented in our errata.