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brewpi/docs/hendi_lockout_findings.md
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jensandClaude Sonnet 5 bc0aeb0ffd docs: update hendi lockout findings with v1.14 retest results
Firmware v1.14 makes --reset (DTR/RTS toggle) reliably clear the
ungraceful-disconnect lockout, unlike v1.12. A plain reconnect without
--reset still fails on both versions, so recovery is specifically tied
to the reset line, not just a fresh connection.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GpePKZiEZWbGo9HrfuML6U
2026-07-02 17:54:28 +02:00

2.2 KiB

Hendi remote-control lockout findings

Reproduced and verified on real hardware using scripts/hendi_ctrl_app.py's --trigger-error-state, --reset and --test-heater flags, across two firmware versions (getSoftwareVersion() / I?+V? via components/actor/hendiCtrl.py).

Trigger

Calling remoteEnable(True) (R1) and then disconnecting/exiting without a matching remoteEnable(False) (R0) - i.e. an ungraceful disconnect while remote control is enabled - puts the device into a locked-out state.

Recovery attempts - v1.12 vs v1.14

v1.14 flashed via --update-firmware HendiCtrl_0114.srec; getSoftwareVersion() confirmed v1.14 afterward.

Recovery method Mechanism v1.12 (original) v1.14 (firmware fix)
Plain reconnect, no --reset Fresh serial connection only, no DTR/RTS toggle Fails Fails - unchanged, a bare reconnect alone still does not clear the lockout
--reset, isolated process Soft reset via DTR/RTS toggle, no power loss Fails (one fluke recovery when combined with --test-heater in the same process/connection - not reproducible in isolation) Recovers - reproducible across two independent trigger/reset/verify cycles
Physical power cycle (device knob) Full power-off/on of the unit Recovers Not retested on v1.14 (superseded by --reset working)

Symptom while locked out

  • I? / V? (software identifier/version queries) still respond normally.
  • R1 (remoteEnable(True)) fails with a communication error - this is the only observed symptom, and it blocks any command path that needs remote control enabled (e.g. --test-heater).

Conclusion

On firmware v1.12, only a physical power cycle clears the lockout; neither a serial soft-reset nor a fresh serial reconnect does reliably.

Firmware v1.14 fixes this partially: a soft reset (--reset, i.e. toggling the DTR/RTS line) now reliably clears the lockout, confirmed across two independent trigger/reset/verify cycles - no physical power cycle needed. However, a plain reconnect without --reset still does not clear it, so the fix specifically ties recovery to the DTR/RTS reset line rather than to any new connection.