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#39 Critical failure on total sensor loss with certain bus confs


Following conditions must be met in order to trigger
this bug:

- All 1-Wire sensor must depart
- HVAC actuator must be 1-Wire driven
- HVAC actuator 1-Wire devices must be gone too

When this happens, repetitive attempts to write
commands to the HVAC actuator 1-Wire devices prevent
proper bus rescans, and therefore DAC gets stuck on
trying to shut off the HVAC instead of properly
detecting the sensors that very well may be back in a
few seconds.

Obviously, this race condition exists regardless of the
layout, so a generic solution to prevent 1-Wire rescan
and device access must be properly implemented (there's
a skeleton already, but it seems to fail in this case).

It must be noted that if it so happens that HVAC
actuator 1-Wire devices are still accessible, the
system works as intended - HVAC is properly shut off on
sensor loss, and restarted when the sensors come back.

This is a hint that sensor network better be separated
from the actuator network.


  • Vadim Tkachenko

    Vadim Tkachenko - 2004-01-22

    Logged In: YES

    Alleviated the problem by doubling the retry delay - write
    command doesn't interfere with the rescan that much anymore.

  • Vadim Tkachenko

    Vadim Tkachenko - 2004-01-22
    • status: open --> closed-fixed

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