fix: ESP32 hard_reset now sets DTR before toggling RTS

[mangelajo]

Summary

• Fix hard_reset: On ESP32 boards with the classic auto-program circuit (two cross-coupled NPN transistors, e.g. ESP32 DevKitC), EN is only pulled low when DTR and RTS are in opposite states. The previous hard_reset only toggled RTS without controlling DTR, so it was ineffective when DTR happened to be in the wrong state. Now explicitly de-asserts DTR before toggling RTS.
• Improve enter_bootloader docs: Updated comments to accurately describe the transistor circuit behavior (DTR/RTS pin states → EN/IO0 effects) instead of the misleading direct-pin comments.
• Strengthen tests: test_hard_reset and test_enter_bootloader now verify the exact DTR/RTS signal sequences using PropertyMock, rather than just checking the methods don't crash.

Test plan

• All 11 existing tests pass (make pkg-test-jumpstarter-driver-esp32)
• test_hard_reset asserts DTR=[False], RTS=[True, False]
• test_enter_bootloader asserts DTR=[False, True, False], RTS=[True, False]
• Manual verification on an ESP32 DevKitC board that hard_reset now correctly resets the chip

Made with Cursor

[netlify]

✅ Deploy Preview for jumpstarter-docs ready!

Name	Link
🔨 Latest commit	cac8287
🔍 Latest deploy log	https://app.netlify.com/projects/jumpstarter-docs/deploys/69bbebe428afe400081c24d3
😎 Deploy Preview	https://deploy-preview-342--jumpstarter-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: be9ef46d-8c97-49ad-bc65-dd9fd372c1ad

📥 Commits

Reviewing files that changed from the base of the PR and between bb7493b and cac8287.

📒 Files selected for processing (2)

• python/packages/jumpstarter-driver-esp32/jumpstarter_driver_esp32/driver.py
• python/packages/jumpstarter-driver-esp32/jumpstarter_driver_esp32/driver_test.py

---

📝 Walkthrough

Walkthrough

Updated the ESP32 driver's hard_reset method to explicitly de-assert DTR before manipulating RTS, improving GPIO control sequencing for proper auto-program circuit behavior. Enhanced docstrings and test coverage to document and verify the explicit DTR/RTS pin control sequence.

Changes

Cohort / File(s)	Summary
ESP32 Reset/Bootloader Control Logic python/packages/jumpstarter-driver-esp32/jumpstarter_driver_esp32/driver.py	Modified hard_reset to call set_dtr(False) before set_rts(True), adding explicit DTR de-assertion. Updated docstrings for both hard_reset and enter_bootloader methods to clarify classic auto-program circuit behavior and alignment with esptool's "ClassicReset" semantics.
GPIO Control Tests python/packages/jumpstarter-driver-esp32/jumpstarter_driver_esp32/driver_test.py	Added _make_mock_serial() helper for tracking DTR/RTS property assignments via PropertyMock. Enhanced test_hard_reset and test_enter_bootloader with assertions verifying exact GPIO state sequences: dtr=[False] and rts=[True, False] for reset; dtr=[False, True, False] and rts=[True, False] for bootloader entry.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• esp32: introduce esp32 driver #294: Adds PySerial set_dtr and set_rts method exports that directly enable the GPIO control changes in this PR.

Suggested reviewers

• evakhoni

Poem

🐰 Reset lines dance with DTR's grace,
RTS follows at the perfect pace,
ClassicReset's way we now obey,
GPIO sequences saved the day! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 37.50% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely summarizes the main change: setting DTR before toggling RTS in the hard_reset method for ESP32 boards.
Description check	✅ Passed	The description is detailed and directly related to the changeset, explaining the technical rationale for the fix, documentation improvements, and test enhancements.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch esp32-reset

📝 Coding Plan

• Generate coding plan for human review comments

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}