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Hifiberry amp 2 with Geekworm ups hat

Michael Rockenbauer

December 17, 2018 20:07

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Hello,

I am currently working on building my own bluetooth car radio. I use the Pi 3B and the hifiberry amp2 and the official raspi display.

Display with amp2 works fine. Same with Display and ups hat.

The only thing that I currently can't really work out is if i can add a UPS hat to the system since i don't want the pi to be brutally shut down (corrupting the SD card is one of my concerns).

I do have the geekworm ups hat which works fine but what i want to know is if I can stack the ups onto the pi and the amp2 onto the UPS. And I'm kinda scared to just stack the hats onto each other since i'm worried about damaging components.

If stacking does not work would it be possible to modify this setup so that the amp2 supplies the UPS with power and the UPS supplies the pi?

 

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5 comments

• 1
  
  HiFiBerry team December 17, 2018 20:21

  Most likely this won't work at all. As the Amp2 uses more than the single voltage of the Raspberry Pi, it's not possible to just add a 5V UPS.
  
  

  Best regards,
  Daniel

• 1
  
  Michael Rockenbauer December 17, 2018 20:24

  Hello Daniel,

  and how about cutting all 5v and 3.3V pins from the ups hat and connecting the 5v from the amp2 to the ups, thats what im trying right now

• 1
  
  HiFiBerry team December 17, 2018 20:26

  This can damage the Amp if the power goes down as the "internal" voltage will be higher then the "external" voltage. If you want to use an UPS, you need to do it on the 12V side, not on the Raspberry Pi side.

  Best regards,
  Daniel

• 1
  
  Michael Rockenbauer December 17, 2018 21:38

  Hey Daniel,

  so ... I just did what i said and it works flawlessly, I just cut off the 5V and 3.3V pins from the UPS and connected the 5v from the amp2 to the UPS hat via a micro usb cable.

  Once i turn off the 12V (right side) the amp2 is being powered with 5V and it just kinda works either way, sound stops for a second and then returns. I guess the only difference is that there will be a significant output power decrease from the amp2.

  I can turn the turn the raspi off when it detects that the battery has lost capacity charge.

  Here's what it looks like:

  
   

  The only problem is that my UPS is kinda "dumb" since it is not capable of starting the Pi once the 12V returns. i manualy have to press a button to start everything again.

  Edited by Michael Rockenbauer December 17, 2018 21:40
• 0
  
  Michael Rockenbauer December 18, 2018 18:43

  Update

  Today i tried this setup actually inside of my car and it behaves the same way.

  If the 12V supply is cut off, there is a limited amplification for the output power - as expected.

  Once the 12V are reconnected everything works as intended.

  Next step is replacing the raspi ups with a smarter one, or to make sure i have a ups on the 12V side.