0

Weird trinket m0 issue
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Weird trinket m0 issue

by gowenrw on Wed Mar 20, 2019 12:36 am

I have two trinkets purchased about a month apart and one runs my circuit python test code fine spinning the on board dot weather plugged into my pc or a usb power bank. The newer one will run the code fine when plugged into the pc but when plugged into a usb power bank it just lights red and blue solid on the dot.
Same code and same power bank and pc being used for both. So, I am wondering if this is an indication of a problem with the new board or just maybe a circuit python boot loader version difference between them (im new to the trinket and have not figured out how to check what version is on each yet).
Has anyone else seen this behavior?
Thanks.

gowenrw
 
Posts: 3
Joined: Wed Mar 20, 2019 12:25 am

Re: Weird trinket m0 issue

by adafruit_support_mike on Wed Mar 20, 2019 2:11 am

Check the amount of current each board uses when connected to a 5V power supply or a LiPo.

Some USB power bricks shut down if the load doesn't draw enough current. It's an efficiency measure, to make the internal battery last longer. One Trinket M0 might use a little more current than the other, and the difference happens to be enough to make the USB power brick shut off.

adafruit_support_mike
 
Posts: 58878
Joined: Thu Feb 11, 2010 2:51 pm

Re: Weird trinket m0 issue

by gowenrw on Wed Mar 20, 2019 8:04 am

The USB power brick is not powering off since it does continue to power the trinket and light red and blue on the dot. That particular trinket just isn't cycling through the dot colors when on the brick but does when on pc power. Its like the main loop is stuck. The dot color cycle code is from the preloaded example main.py. And this works fine on another trinket on the power brick and works fine on this trinket when using pc power.
Here is another test I did that could maybe help diagnose. The USB power brick I was using in my previous tests has a max amp output of 1A. When I try this board using a bigger brick with 2A output this trinket works. Should a trinket with nothing external hooked up to it be drawing more than 1 amp of power?

gowenrw
 
Posts: 3
Joined: Wed Mar 20, 2019 12:25 am

Re: Weird trinket m0 issue

by gowenrw on Wed Mar 20, 2019 10:19 pm

I finally solved this. It turns out that the newer trinket that I was having issue with came loaded with CircuitPython 3.1 where the older one had 2.1. (Took me a bit to figure that out since I am new to the trinket and circuitpython) Maybe something is more power efficient in the 3.1 code that caused it to not fully activate the usb power brick. But back revving to 2.1 fixed the issue for now. I'll test again at 3.1 once I build a circuit for it that is drawing more power. Thanks for the help.

gowenrw
 
Posts: 3
Joined: Wed Mar 20, 2019 12:25 am

Re: Weird trinket m0 issue

by adafruit_support_mike on Thu Mar 21, 2019 3:50 am

Glad to hear you found the issue.

One easy way to increase the current load on the USB brick is to put a resistor between the 5V and GND pins. A 1k resistor will add 5mA of load, which might be enough to meep things running.

adafruit_support_mike
 
Posts: 58878
Joined: Thu Feb 11, 2010 2:51 pm

Please be positive and constructive with your questions and comments.