MGL Avionics User Forum

I'm not convinced the C2032 battery in my iEFIS Lite is doing its job. Come to that, I'm not 100% about the 'keep alive' wire either. I say this because every time I power down the unit it forgets the radio settings and I have to reset the intercom volume, squelch, aux volume etc each time. The iEFIS is wired up to a Trig TY96 via an Extender.

My understanding is the 'keep alive' wire should ensure everything is held in the iEFIS memory and if this fails etc then the C2032 will do the same thing for a limited time.

So, the iEFIS has been removed from the aircraft and is sitting on my desk. Obviously there is no 'keep alive' wire plugged in. My intention is to change the C2032 battery BUT what I want to know BEFORE I remove it is will all my settings be lost? There are a LOT of different settings that have been adjusted over time and I really do not want to lose them.

I think I should have probably backed them all up to the SD card before removing it from the aircraft. I will do that if it's not safe to remove the battery but wanted to check what gets saved before doing any of that.

Cheers

Those settings are kept in the radio I believe. They are not stored in the EFIS non-volatile memory at all.
Will have to get one working here to check.

The EFIS has several different memories. The biggest one is a dynamic memory - that is used for nearly everything. But that looses content when you switch off. It would use too much power to keep alive.
Then we have a dedicated low power static RAM chip. That contains your GPS track you can extract as Google KML file. The remainder of this chip contains a few hundred items the EFIS needs to remember. For example your last GPS position, various map settings like zoom, barometric pressure, heading and altimeter bugs - basically things that can change often that would wear out other memories like E2 or Flash memories.
Then we have a dedicated flash memory. That contains your "crash log" as we call it - about the last 30 minutes to 1 hour or flight data and a few critical setup items we can't afford to loose.
Then there are a few memories scattered around inside the processor chip that are particularly fast - these are used to perform tasks that need to be, well, fast. A lot of that has to do with graphics.

Thank you for that info Rainier and it would be very interesting to see how you get on with the radio. It NORMALLY remembers the last frequencies but volumes, squelches etc revert to default. How about settings such as autopilot, transponder, types of screens to display (custom) etc? Should I back those up before the C2032 is removed or won’t it matter?

Basically as a rule of thumb - anything you setup in the setup menu or other setups that are expected to change very infrequently (or never) do not rely on the battery.
Battery is used for items that would typically change pretty often as the storage never wears out.

It has become fairly normal in many devices to use E2 and flash memories to store things that change fairly frequently as this can be done at low cost and you do not have to hassle with batteries - but these memories do wear - you can read them with only very minor degrading (but still some) but writing them is a problem. Typically you have between 10.000 to 100.000 write cycles per bit, a few can stretch a bit more. So we did not want to go that route as obviously we would be intentionally build in guaranteed premature failure.
Battery backed low power static RAM is still the best solution for this at this point.

BTW, flash memories, used practically everywhere now are highly interesting. While we are still trying to get out heads around quantum mechanics - here is a nice example of this being used. We transfer electrons from one place to another - but they never go through the space in between ! It's magic.

I managed to plug the EFIS into the power and backed up the setup files to the SD card before changing the battery (with the unit now unplugged).

A few minor things were lost (virtual fuel tank went to zero) and I'll have to take a look at the transponder because the ADSB track didn't show up on FR24 after the flight. The battery/power change probably got rid of something like the air switch setting, so should not be a big deal to reinstate that. The autopilot settings all seemed to be okay.

Unfortunately the radio is still losing the things I mentioned above, so any pointers to save having to reset before each flight will be gratefully received

I was listening to a Chinese professor the other day on the radio talking about quantum computers. WOW!! He gave a brief explanation of the theory etc but then put it into context by comparing a problem that would take the most powerful computer we have at the moment on Earth and the quantum computer they are working on. Theoretical only, of course, but he was saying a problem that would take today's computer a few BILLION years to solve could be solved by the quantum machine in minutes And I thought my 386 DX 100 with 40mb of memory was powerful