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Bottom preset bug

A project log for Standing desk remote control

Control multiple desks over wifi

lion-mclionheadlion mclionhead 09/17/2022 at 08:170 Comments

So the preset bug affecting maximum height also showed itself on some desks affecting minimum height.  The same workaround is needed for minimum height on 2 desks.  If a user sets the max & min height presets to middle height, the bugfix won't do anything.

Then tests showed the hall effect sensors are ratiometric down to 2.8V.  Then, the min & max output starts clipping in greater amounts from the rails as the battery voltage drops while the center voltage stays ratiometric.  The transmitter would now be powered by an ancient mic2251 boost converter that generates a constant 3.66V all the way from 2.2V in.   Not bad for a boost converter rated for 2.5V input.  In the age of recycled parts, standard 3.3V & 5V are gone.  

The days of cleaning flux are over unless the circuit is seriously affected.

That didn't make any difference in the middle 2 positions, but gave the top & bottom more separation.  More importantly, it won't die when the batteries aren't fully charged.  Not bad for a sensor rated for 4.5V.  Mechanical play continues to be the mane problem.  An old fashioned pot would be subject to shaft play & noise from dirt.  Multimeter selectors use gold traces, which would be expensive to manufacture.  The dial has proven to be a fast, convenient way of selecting desks.

Many placements of the board on the bare frame have been tried.  The mane problem is exposing the IR receiver.

The full down bug is intermittent at best.  If the lion kingdom didn't reverse engineer the preset signals & develop a custom controller, the world would never have worked around the top & bottom preset bugs.

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