Hi,
is there anything new regarding this problem?
How should we handle this?
Cheers!
Meino
Analysis result of: HW Fail?:Feather M4 Express: Read LiPo v
Moderators: adafruit_support_bill, adafruit
Please be positive and constructive with your questions and comments.
- mcc
- Posts: 101
- Joined: Sat Apr 21, 2012 9:19 am
- mcc
- Posts: 101
- Joined: Sat Apr 21, 2012 9:19 am
Re: Analysis result of: HW Fail?:Feather M4 Express: Read Li
Hello Adafruit,
regarding your post:
viewtopic.php?f=57&t=144097&start=15#p718169
...are you still reading this thread?
Still no clue what is broken with this board?
No idea, whether it is valid what superduty and me has found?
Can we hope for any answer?
Cheers!
Meino
regarding your post:
viewtopic.php?f=57&t=144097&start=15#p718169
...are you still reading this thread?
Still no clue what is broken with this board?
No idea, whether it is valid what superduty and me has found?
Can we hope for any answer?
Cheers!
Meino
- adafruit2
- Posts: 22194
- Joined: Fri Mar 11, 2005 7:36 pm
Re: Analysis result of: HW Fail?:Feather M4 Express: Read Li
we are but we have no idea still, and have not had a lot of time to research it. sorry :(
- mcc
- Posts: 101
- Joined: Sat Apr 21, 2012 9:19 am
Re: Analysis result of: HW Fail?:Feather M4 Express: Read Li
Hi,
me again...sorry.
Now two month gone...still no idea, what's going on?
Still no fix or workaround?
Still same boards sold?
Sorry for feeling left alone with this...
Cheers,
mcc
me again...sorry.
Now two month gone...still no idea, what's going on?
Still no fix or workaround?
Still same boards sold?
Sorry for feeling left alone with this...
Cheers,
mcc
- adafruit2
- Posts: 22194
- Joined: Fri Mar 11, 2005 7:36 pm
Re: Analysis result of: HW Fail?:Feather M4 Express: Read Li
hiya - its been a while and i want to recall where we were at. so i think last we checked, the voltage reading of the divider is OK and the math is correct as long as AREF is 3.3V but once the battery drops, AREF droops down so the math no longer works.
so the only real solution is to change AREF, right?
i've started draining a battery down to reproduce it
so the only real solution is to change AREF, right?
i've started draining a battery down to reproduce it
- superduty
- Posts: 21
- Joined: Wed Nov 06, 2013 1:24 pm
Re: Analysis result of: HW Fail?:Feather M4 Express: Read Li
Please review my posts on 26 Dec 2018 20:52 and 27 Dec 2018 15:31 to get my summary of the issue.
My conclusion was that the mosfet was not getting turned on properly when running on battery power only.
My conclusion was that the mosfet was not getting turned on properly when running on battery power only.
- mcc
- Posts: 101
- Joined: Sat Apr 21, 2012 9:19 am
Re: Analysis result of: HW Fail?:Feather M4 Express: Read Li
Hi,
.....?.....
It has already been analysed be superduty and me. What is the problem?
If something is not understood both of are here to help and to get finally
a M4 Feather Express, which works as advertised at the time we bought it...
Waiting...
mcc
.....?.....
It has already been analysed be superduty and me. What is the problem?
If something is not understood both of are here to help and to get finally
a M4 Feather Express, which works as advertised at the time we bought it...
Waiting...
mcc
- adafruit2
- Posts: 22194
- Joined: Fri Mar 11, 2005 7:36 pm
Re: Analysis result of: HW Fail?:Feather M4 Express: Read Li
sure, but how to fix it without breaking somtehing else? :)
we need to use a schottky diode, so the only other option would be to decrease the size of the pulldown on the mosfet
mcc, did you try adding a 2.2K resistor?
we need to use a schottky diode, so the only other option would be to decrease the size of the pulldown on the mosfet
Code: Select all
Per a previous post, I added a 4.7k resistor from VUSB to ground. That seemed to bleed off the leakage voltage and enabled the mosfet to turn on when running on battery. I have now switched that to a 2.2k. The measured current through the 2.2k resistor is only 70 micro-amps and it pulls the voltage on VUSB down to 155 milli-volts. I am now in the process of letting the battery discharge while looking at both the VBAT voltage and input to the regulator both with and without the 2.2k resistor.
Please be positive and constructive with your questions and comments.