Why is the low battery LED is always on on the MCU?

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BITalino
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Why is the low battery LED is always on on the MCU?

Postby BITalino » Fri Mar 06, 2015 10:54 am

The red light on the MCU is turned on by the BITalino firmware when the input value on pin A6 is bellow a programable threshold:
http://forum.bitalino.com/viewtopic.php?f=9&t=43#p54

In normal conditions, for that LED to be on, one of three things should be happening:

1) ABAT pin on the power block not connected to A6

2) ABAT pin always has a voltage always bellow 1.7V (which may be indicative of a faulty battery or a faulty component on the voltage divider circuit connected to the battery to provide the ABAT pin)

3) The device is being controlled directly (e.g. by the API), and the low battery indicator activation threshold is being set to a very low number using the battery(…) method (e.g. http://bitalino.com/pyAPI/#bitalino.BITalino.battery)


NOTE THAT ON THE BITalino Plugged, by default ABAT is disconnected from the A6 channel in order to enable the use of A6 for sensor connection, reason for which the low battery LED will always be on.

If you want to use A6 for low battery indication on the BITalino Plugged, you can shunt the two pads to the right of the JST connector on the PWR block, but be careful not to connect any sensor to A6 afterwards.

Currently you can use A6 for low battery or for sensor connection but not for both. This is something that will be changed in our BITalino (r)evolution device, to be launched later this year, and which will have an extra channel dedicated for the battery .

Best regards,
The BITalino Team

uha666
Posts: 13
Joined: Tue Aug 18, 2015 4:51 pm

Re: Why is the low battery LED is always on on the MCU?

Postby uha666 » Thu Aug 20, 2015 8:47 pm

Hi,

I have the bitalino plugged and i can only activate the ABAT reading by shunting the two pads as described beside the JST conector. However i would rather not have that shunt permanent, is there any other conection on the board i can make using the pins (with a dupont cable jumper) so it can be easy to connect/disconnect the ABAT to the A6?

Regards,

BITalino
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Posts: 567
Joined: Tue Aug 27, 2013 3:47 pm

Re: Why is the low battery LED is always on on the MCU?

Postby BITalino » Thu Aug 20, 2015 9:12 pm

Hi there,

You can definitely do that by soldering a female PCB header (or equivalent) to the pins labelled A6 on the MCU block and ABAT on the PWR block.

This way whenever a cable jumper is in place you have the battery monitoring function, and when its not you can use A6 for sensor data input.

Best regards,
The BITalino Team

uha666
Posts: 13
Joined: Tue Aug 18, 2015 4:51 pm

Re: Why is the low battery LED is always on on the MCU?

Postby uha666 » Thu Aug 20, 2015 10:29 pm

Hi,

I did that but it doesn't do anything. I can still only get a signal if i bridge the two pads.

Am i missing something?

Regards.

BITalino
Site Admin
Posts: 567
Joined: Tue Aug 27, 2013 3:47 pm

Re: Why is the low battery LED is always on on the MCU?

Postby BITalino » Thu Aug 20, 2015 10:34 pm

Note that you shouldn't have any sensor connected to the A6 plug. Do you have the chance to compare the voltage on the bottom pad with the voltage on ABAT and report back?

Thanks,
The BITalino Team

uha666
Posts: 13
Joined: Tue Aug 18, 2015 4:51 pm

Re: Why is the low battery LED is always on on the MCU?

Postby uha666 » Thu Aug 20, 2015 10:38 pm

The voltage is 3.83v on the bottom pad and 0v on ABAT (without the two pads being shorted)

Regards.

BITalino
Site Admin
Posts: 567
Joined: Tue Aug 27, 2013 3:47 pm

Re: Why is the low battery LED is always on on the MCU?

Postby BITalino » Thu Aug 20, 2015 10:45 pm

Can you share a picture of your PWR block?

Thanks,
The BITalino Team

uha666
Posts: 13
Joined: Tue Aug 18, 2015 4:51 pm

Re: Why is the low battery LED is always on on the MCU?

Postby uha666 » Thu Aug 20, 2015 11:42 pm

Image

BITalino
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Posts: 567
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Re: Why is the low battery LED is always on on the MCU?

Postby BITalino » Fri Aug 21, 2015 2:46 pm

Thanks,

In your version of the BITalino Plugged you have two options:

1) With the two pads unconnected, you can put a 30k resistor in series with the jumper wire.

2) With the two pads connected, you use an x-cutter to cut the via passing through the area highlighted in yellow in the attached picture and simply use the jumper wire.

Let us know how this works out or if you have further questions.

Best regards,
The BITalino Team

image3063.jpg
image3063.jpg (61.38 KiB) Viewed 2558 times

uha666
Posts: 13
Joined: Tue Aug 18, 2015 4:51 pm

Re: Why is the low battery LED is always on on the MCU?

Postby uha666 » Mon Aug 24, 2015 11:09 pm

Hi,

I can't see the picture you posted it tells me i don't have permission.

Regards


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