fix(ulp): Ulp core does not start with UlpCoreWakeupSource::HpCpu.

[puyogo-suzuki]

Pull Request Details 📖

Description

This PR fixes a regression where the ULP core fails to start when using UlpCoreWakeupSource::HpCpu. This issue was introduced in #5134.

Specifically, the lp_blinky example currently hangs because the ULP core never starts. The root cause is that the sleep timer is not enabled within ulp_config_wakeup_source when this wakeup source is selected.

This PR resolves the issue by ensuring the timer is enabled even when UlpCoreWakeupSource::HpCpu is specified. The timer is configured to wake the ULP core immediately.

Detailed explanation

According to Section 2.4 of the ESP32-S3 Technical Reference Manual (v1.8), the sleep timer must be enabled to wake the ULP core, even when triggered by RTC GPIO or software:

1. Flash the program to be executed by ULP coprocessor into RTC slow memory.
2. Select the working ULP coprocessor by configuring RTC_CNTL_COCPU_SEL.
3. If ULP-RISC-V is selected as working ULP coprocessor, please set and reset RTC_CNTL_COCPU_CLK_FO; set RTC_CNTL_COCPU_CLKGATE_EN.
4. Set sleep cycles for the timer by configuring RTC_CNTL_ULP_CP_TIMER_1_REG.
5. Enable the timer by software or by RTC GPIO;

• By software: set RTC_CNTL_ULP_CP_SLP_TIMER_EN.
• By RTC GPIO: set RTC_CNTL_ULP_CP_GPIO_WAKEUP_ENA.

In ESP-IDF, there is no direct equivalent to our UlpCoreWakeupSource::HpCpu.
Instead, it defaults to ULP_RISCV_WAKEUP_SOURCE_TIMER:
ulp_riscv.h#L32 (esp-idf)

Discussion

I have set the sleep cycles (RTC_CNTL_ULP_CP_TIMER_SLP_CYCLE) to 0 to ensure the ULP core wakes up immediately once the timer is enabled.
However, the hardware default value is 200.
Should I use the hardware default?

Testing

Tested with the lp_blinky example on an ESP32-S3-DevKitC-1:

• Before this PR: The LED does not blink, and the counter remains at 0 (stuck).
• After this PR: The ULP core starts correctly, the LED blinks, and the counter increments as expected.

Submission Checklist 📝

• I have updated existing examples or added new ones (if applicable).
• I have used cargo xtask fmt-packages command to ensure that all changed code is formatted correctly.
• My changes were added to the CHANGELOG.md in the proper section.
• I have added necessary changes to user code to the latest Migration Guide.
• My changes are in accordance to the esp-rs developer guidelines

Extra:

• I have read the CONTRIBUTING.md guide and followed its instructions.

[Copilot]

Pull request overview

Fixes a regression in the ESP32-S2/S3 ULP core bring-up path where UlpCoreWakeupSource::HpCpu would not start the ULP core because the ULP sleep timer wasn’t enabled (regression introduced by the timer-support work in #5134).

Changes:

• Refactors ULP wakeup-source configuration to share timer setup via a local helper.
• Ensures UlpCoreWakeupSource::HpCpu also enables the ULP sleep timer (configured for immediate wake) so the ULP core actually starts.
• Applies the same fix to both ESP32-S2 and ESP32-S3 implementations.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
esp-hal/src/soc/esp32s3/ulp_core.rs	Enables/configures the ULP sleep timer even for HpCpu wakeup to avoid ULP start hang on ESP32-S3.
esp-hal/src/soc/esp32s2/ulp_core.rs	Mirrors the same wakeup-source/timer enabling fix for ESP32-S2.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

[puyogo-suzuki]

I don't know why the changelog check fails.

Caused by:
    Changelog line This release was made possible via the following pre-releases: starts with unexpected character

I verified that the added line starts as same as the other lines.

[github-actions]

New commits in main has made this PR unmergable. Please resolve the conflicts.

[bjoernQ]

There was a problem with the changelog format - it's fixed on main and a rebase should fix it

I guess otherwise this is fine

[bugadani]

@leighleighleigh could you please take a look at this PR?

[puyogo-suzuki]

Thank you for the review.
I have updated CHANGELOG based on your suggestion.

• ESP32-S2, ESP32-S3: Fixed a bug where UlpCore.run() with UlpCoreWakeupSource::HpCpu fails to wake the ULP Core (fix(ulp): Ulp core does not start with UlpCoreWakeupSource::HpCpu. #5410)

Do you have any further suggestions?

[github-actions]

New commits in main have made this PR unmergeable. Please resolve the conflicts.

[leighleighleigh]

@bugadani I have reproduced this, and confirmed the changes fix the regression.
Thanks @puyogo-suzuki ! :)

[bugadani]

Thank you both!

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.