er9x TX display the battery voltage will float!!!

[woody088]

Hello, everyone!
I use 3S of Lipo battery, the display voltage will be too low, about 10.7v, but after a few minutes to see displayed voltage will become 14.5v!???? Such a big difference!
Before using the 3S LiFePo4 battery is no such problem.
What is the problem!? Need to update the firmware? Or hardware needs to be done to modify?
ps: my firmware is r433
Thank everyone~

[MikeB]

You may have a faulty bandgap reference in the processor.
Go to the analog display DIAG screen (LEFT LONG, then LEFT a couple more timer. On the right of that screen is a number under BG. This number should stay almost constant. See what it is after switch on, then later when the voltage reading has changed.

Mike.

[woody088]

You may have a faulty bandgap reference in the processor.
Go to the analog display DIAG screen (LEFT LONG, then LEFT a couple more timer. On the right of that screen is a number under BG. This number should stay almost constant. See what it is after switch on, then later when the voltage reading has changed.

Mike.

BG values ​​in the ANA from where (Schematic)!?

[gohsthb]

The bandgap is a reference voltage. It is internal to the processor.
-Gohst

[Camboui]

5th screen in tx setup.

[woody088]

The bandgap is a reference voltage. It is internal to the processor.
-Gohst

SO....BG value is unstable, I should have ....
(1) Check the +5 voltage stability or not?
(2) re-burn the latest stable version of firmware?
(3) Replace a new processor?

Please tell me you suggest how should I do!? Thx you!!

[MikeB]

In the main RADIO SETUP menu there is a BANDGAP option. Just turn it off and re-calibrate your battery voltage reading. The bandgap was added for those using lower supply voltages. There is a problem once the battery drops below about 7.0 volts, it is not accurate, and even starts to indicate an increasing voltage when the battery is actually dropping.
Since you have a 3S battery, you should not get as low as 7 volts.

Mike.

[woody088]

In the main RADIO SETUP menu there is a BANDGAP option. Just turn it off and re-calibrate your battery voltage reading. The bandgap was added for those using lower supply voltages. There is a problem once the battery drops below about 7.0 volts, it is not accurate, and even starts to indicate an increasing voltage when the battery is actually dropping.
Since you have a 3S battery, you should not get as low as 7 volts.

Mike.

thx Mike!
But my firmware version R443, this version does not have Bandgap option on / off function.
I can not understand why the TX battery voltage> 12 volts, the voltage flowing!
Others have the same problem like me using 3S lipo!?
I use 3S LiFePo4 now, its voltage is lower than the 3S of Lipo is not flowing
To ask questions - just want to try to find out the real problem, and to fix it

[MikeB]

I can't remember when the bandgap was introduced, nor when the option to turn it on/off was put in. The latest revision is 762, so r443 is quite old.
I added the bandgap on/off later because of the few who had problems with it.

Can you confirm if you have a "BG" value on the analog display screen, and if so, it is changing a lot?

Mike.

[woody088]

I can't remember when the bandgap was introduced, nor when the option to turn it on/off was put in. The latest revision is 762, so r443 is quite old.
I added the bandgap on/off later because of the few who had problems with it.

Can you confirm if you have a "BG" value on the analog display screen, and if so, it is changing a lot?

Mike.

[BBvideo 425,350]http://www.youtube.com/watch?v=9Fcqfja0D-Y[/BBvideo]

[MikeB]

Yes, your BG (bandgap) value is wandering. Mine reads 250 at switch on and just stays there. Unfortunately, the bandgap device is part of the processor, so we can't do anything about it. You need to disable the use of the bandgap. If you don't have an option fir this in the revision you are running, you will need to upgrade to a later version.

Mike.

[woody088]

I remember at first in write er9x firmware, I have errors will be error FUSE value written ATMega64A
Later, the correct fuse value written
But I do not know whether it is correct?
Bandgap values ​​floating have associated with it?
Will the th-9x ATMega64A,The correct value of the FUSE is 0x??????

[chapterone]

I can't remember when the bandgap was introduced, nor when the option to turn it on/off was put in. The latest revision is 762, so r443 is quite old.
I added the bandgap on/off later because of the few who had problems with it.

Can you confirm if you have a "BG" value on the analog display screen, and if so, it is changing a lot?

Mike.

Hello,
I loaded the r85 binary that Mike released 25/6, and there is no band gap in the ana-screen.
Is this correct or not?
I use 2s lipo and what I understand from this discussion it should be wise to set band gap ON.
Do I have to switch it on in another menu?

Kenth

[gohsthb]

r85 is from 2010. Start by upgrading to the latest revision, you will find it much improved!
-Gohst

[chapterone]

r85 is from 2010. Start by upgrading to the latest revision, you will find it much improved!
-Gohst

But what does this post from Mike means from 26/5 2012?

"OK folks, r85 binary now released. In general it is the same as the last version, but running under the real time operating system CoOS."

This is also the latest binary that C9x load.

Kenth

[Kilrah]

This is for the ersky9x replacement board.
Do you have one? You didn't say what you were actually using, so we assumed it's the stock board. Ersky9x doesn't have bandgap.

[chapterone]

This is for the ersky9x replacement board.
Do you have one? You didn't say what you were actually using, so we assumed it's the stock board. Ersky9x doesn't have bandgap.

Ok I see,
Thats the reason why I can't see it. Yes I have Ersky9x board.

Does this also mean that I don't need to think about the low voltage below 7.0 v ?

Kenth

[jhsa]

can you please post a picture of you board? I think that there is some confusion here..

[MikeB]

The ersky9x board works down to below 5.5V supply, and accurately reports the supply voltage down to 4 volts or less. It doesn't have or need a bandgap.
THe Tx module is likely to need 6V minimum, FrSky modules have that in their specification.

Mike.

[woody088]

What's the ER9X correct value of the FUSE 0x??????
thx!

[MikeB]

Mine are set to:
Extended 0xFF
High 0x81
Low 0x0E

Mike.