24 January 2016

Hafiz Adewuyi

AC remote control with LCD display

There's some things probably only a programmer gets to bother about. And the one this article is based on looks a lot like a perfect candidate.

In my apartment, each AC has a remote control. Each remote control has an LCD display which indicates the working temperature of the AC. The AC on the other hand does not have a temperature indicator. Which means your only source of information on the AC's working temperature is it's remote control display.

Each time I have to regulate an AC in the apartment, my idle mind often goes out to wonder about what logic the AC - remote control system works with:
UP or DOWN (Case 1)
1. When the '<' or '>' button is pressed once on the remote control and the AC is within range of receiving the signal, the AC's working temperature goes one notch down or up, respectively;

2. When the '<' or '>' button is pressed once on the remote control, the remote control computes the new working temperature (with respect to its current display value), displays it, then broadcasts the value which the AC picks up and intelligently shifts its current working temperature up or down by the required number of notches to attain the broadcast temperature.

POWER ON (Case 2)
Upon instruction to resume operation from a remote control after an explicit shutdown, does the AC:

1. resume work on it shutdown temperature or;

2. take on the display value on the remote control as its waking working temperature?
I make it very obvious, even though it (hopefully) needs no telling that logic 2 is superior in both cases. However, as a programmer, I know how it takes significantly more work to program logic 2 than to just slap in one-way traffic logic 1. 

I've not tried my hands on any hardware programming ever. However, I can imagine it takes an extra device for a remote control to be able to broadcast a number vs. up or down signal. And also, for the AC to read such a signal . What do I know?

It's no surprise that I always operate on the assumption that logic 1 is in place. Hence, the '<' button on the remote control often ends up getting pushed one too many times when am trying to reach minimum temperature.

Do you know which of the logics above is in prevalent use in ACs with no temperature indicator today? I'd love to hear from you. This should be a no-brainer anyway, for any engineer friend of mine who works in the RAC area.

P.S.: I figured out a way to test this. Unfortunately, there's no electricity now. Will update this post as soon as I come around to doing the test.

Off to bed. Nice week ahead.

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