Feather RP2040 On/Off Switch

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AudioOddities
 
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Feather RP2040 On/Off Switch

Post by AudioOddities »

Hi there!

I'm trying to use the RP2040 Feather along with a Li-Po battery plugged into the onboard JST header, but I'd like to be able to switch the device on and off without having to disconnect the battery from the board. I looked in the guide under the power management section and it mentions that, "We bring out the BAT pin, which is tied to the LiPoly JST connector" but without a diagram I'm unsure if I could somehow use this to insert a switch into the circuit for power on/off. Any suggestions or guidance would be appreciated. Thank you so much in advance!

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dastels
 
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Re: Feather RP2040 On/Off Switch

Post by dastels »

Connecting the EN pin to ground disables the onboard 3.3v regulator, powering off the board. This does not interfere with the operation of the battery charger.

Dave

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AudioOddities
 
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Re: Feather RP2040 On/Off Switch

Post by AudioOddities »

dastels wrote: Sun Nov 20, 2022 5:53 pm Connecting the EN pin to ground disables the onboard 3.3v regulator, powering off the board. This does not interfere with the operation of the battery charger.

Dave
Hi Dave,

Thanks so much for the quick reply! I appreciate it. With a 150mAh Li-Poly battery powering the Feather RP2040 via the onboard JST header, pulling the EN pin to ground does seem to power off the board. It does not seem to do what I was hoping though, so perhaps a bit more context will help.

I've got the DotStar Featherwing plugged into the RP2040 Feather directly (backpack style). I wanted to make the whole package portable by using the battery attached to the onboard header, so ideally I could turn the whole thing on and off without unplugging the battery. Pulling EN to ground does turn the board off, and I can see this because the animation running on the DotStar Featherwing stops, but the wing itself is still receiving power as it just hangs on the last frame of the animation that was playing when EN gets pulled down. In my head what I am imagining would be akin to a SPST switch sitting between the JST power lead and the rest of the board circuit. I hope that makes sense (still learning a lot with this stuff). Is something like that possible? Thanks in advance!

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dastels
 
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Re: Feather RP2040 On/Off Switch

Post by dastels »

Odd. See https://learn.adafruit.com/adafruit-dot ... ns-2871465 which states that EN should power off the DotStar matrix as well.

Dave

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AudioOddities
 
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Re: Feather RP2040 On/Off Switch

Post by AudioOddities »

Yea, I saw that and also found it odd. I'm curious to know if the code loop completes when EN is pulled down or if it just suspends activity regardless of where it is in the loop, but even if that was the case it would suggest the wing is still receiving power. I'm gonna keep tinkering to see if I can figure this out, but I do appreciate your suggestion! I'll come back here with the solution if I figure out what's causing that behavior. Thanks again!

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dastels
 
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Re: Feather RP2040 On/Off Switch

Post by dastels »

EN turns off power to the board so everything just stops.. no clean shutdown.

Verify that EN on the wing does get grounded along with the Feather.

Dave

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dastels
 
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Re: Feather RP2040 On/Off Switch

Post by dastels »

OK, I just tested this out (dotstar wing & RP2040 Feather) grounding EN does, in fact, cut power to the DotStars.

Can you post a clear closeup of the soldering on/around the EN pin on each board?

Dave

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AudioOddities
 
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Re: Feather RP2040 On/Off Switch

Post by AudioOddities »

dastels wrote: Sun Nov 20, 2022 9:14 pm OK, I just tested this out (dotstar wing & RP2040 Feather) grounding EN does, in fact, cut power to the DotStars.

Can you post a clear closeup of the soldering on/around the EN pin on each board?

Dave
Sure thing! I did hit the EN post on the wing again just to reflow things to see if that was maybe the issue, but I'm still getting the same behavior. May have cooked it just a bit too long but not too bad I don't think (performs the same as before I hit it again). I've got a solder sucker and can just pull them all and do it over, but I'd prefer not to if you don't think that's the issue. (photos cropped and resized due to file size limitations)
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AudioOddities
 
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Re: Feather RP2040 On/Off Switch

Post by AudioOddities »

Here's one more to show you what I mean. You'll have to trust me that the pins I'm connecting on my breadboard are EN and ground, but that's it there. If I pull EN down at just the right moment when the animation frame refreshes I can get wing to be "off" but it's only cause I timed it just right. If I haphazardly pull EN down it will just stop wherever it is in the animation cycle and 'freeze' as shown in this photo.
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dastels
 
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Re: Feather RP2040 On/Off Switch

Post by dastels »

The soldering looks great.

What happens if you touch the grounded wire to the EN pin on the wing? Just to completely rule out the connection.

Dave

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dastels
 
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Re: Feather RP2040 On/Off Switch

Post by dastels »

Actually, a close up of the end of the wing that's above the USB connector. I'm curious how the FET power switches look.

Dave

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AudioOddities
 
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Re: Feather RP2040 On/Off Switch

Post by AudioOddities »

dastels wrote: Mon Nov 21, 2022 12:11 am Actually, a close up of the end of the wing that's above the USB connector. I'm curious how the FET power switches look.

Dave
I did try ground directly to the wing EN, but the result was the same. Here is a photo of the portion of the wing you're asking about. This was a tricky shot to get since the light does weird things in that spot, but I got it as best as I could. Hope this helps.
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dastels
 
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Re: Feather RP2040 On/Off Switch

Post by dastels »

Hmm... the soldering on those does look a bit "scruffy" compared to the board I have. Please email [email protected] with a link to this thread, your order number, and request the replacement of one DotStar Featherwing (6x12).

Dave

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AudioOddities
 
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Re: Feather RP2040 On/Off Switch

Post by AudioOddities »

dastels wrote: Mon Nov 21, 2022 10:51 am Hmm... the soldering on those does look a bit "scruffy" compared to the board I have. Please email [email protected] with a link to this thread, your order number, and request the replacement of one DotStar Featherwing (6x12).

Dave
Hey Dave,

Will do, and thank you for your assistance! I really appreciate it. Have a great day!

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AudioOddities
 
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Re: Feather RP2040 On/Off Switch

Post by AudioOddities »

Just wanted to follow up here for anyone else that happens onto this thread. My DotStar wing was most definitely malfunctioning and was the reason this didn't work at first. As soon as I popped out the old wing and installed the replacement everything worked exactly as expected. Thanks again Dave for the assist!

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