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powering the amp+, the pi, and the pi's official touch screen display?

David Michel

December 02, 2015 20:47

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Hi,

I'm having issues trying to power the Amp+, the Pi and its display from the same power supply...

The power supply is 12V 3A and the Pi starts up but the display doesn't turn on. The display is powered via the Pi's USB port and that works well when I power the Pi separately via its microUSB port as well...

But...

1) the documentation here says "It is not allowed to connect 5V to the Micro-USB port of the Raspberry Pi"

2) Even if it's not harmful, having to use 2 power supply is a rather awkward.

3) I have to power the Pi first and then power the amp+. The other round doesn't work.

Has anyone seen this? Any idea what to do to fix this?

 

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13 comments

• 0
  
  HiFiBerry team December 02, 2015 20:53

  Hi David, 

  the Amp is not designed to provide enough current for the Raspberry Pi and the display. You should NOT connect an external power supply to the Raspberry Pi while the Amp is connected to it. This might damage the board.

  You might need an additional 5V power supply, but this should only power the display, not the Raspberry Pi.

   

  Best regards
  Daniel

• 0
  
  hifi December 03, 2015 06:52

  Daniel, do you mean I cannot use GPIO power pins (+5V, GND) on AMP to power up LCD? Let's say I connect 12V 5A power supply to AMP and my LCD consumes 100mA maximum. Why should I use additional +5V power supply in this case?

  Thanks!

• 0
  
  HiFiBerry team December 03, 2015 13:14

  The 5V are provided by an internal voltage regulator on the Amp. This is not designed to handle a lot of additional load. This has nothing to do with the external power supply you use. While it might be able to power the display, we can't guarantee this. In general there is a better chance that it will work with an external 12V power supply than with an 18V power supply - as the 12V power supply will generate less heat on the regulator.

  Best regards
  Daniel

• 0
  
  hifi December 03, 2015 15:51

  OK, do you have the numbers? What's the maximum current which AMP on-board 12->5V converter can produce?

  Thanks!

• 0
  
  HiFiBerry team December 04, 2015 05:54

  It's not so easy. That you can put a single number onto this. In general it should be able to provide 700-800mA, but it also depends on environment temperature and air flow. It can provide even more. However, the power supply will become more unstable. 

  Best regards
  Daniel Matuschek

• 0
  
  Loïc Pontani September 11, 2016 09:26

  Hi,

  So, if I well understand, if I want to use both HIFIBERRY AMP+ and the official Pi touchscreen, I will have to cut either the powering of PI from the AMP or the powering of PI from the display.

  Sound that the easier way is to cut the powering pin on the GPIO between PI and AMP+ (and, if I don't want to loose any warranty, have to use a custom cable to link them instead of cutting pin)

  Right ?

  Thanks

• 0
  
  HiFiBerry team September 11, 2016 14:13

  Don't cut any pins. Just use a normal 5V USB power supply for the display. The Amp+ and RPI will be powered by the Amp+ powers supply.

  Best regards,
  Daniel

• 0
  
  Loïc Pontani September 11, 2016 18:32

  Yeah !!

  So stupid !
  Been a long time since I mount the touchscreen so I didn't remember how it is powered.
  Thought it was powered through ribbon cable...
  But you are right, it is simply powered through GPIO so just had to power it through AMP+ instead.

  Thanks for your answer.

• 0
  
  Jack Glasson December 17, 2016 10:58

  If it was easier to cut a GPIO pin which one does the amp use to supply power to the pi?

• 0
  
  HiFiBerry team December 18, 2016 07:54

  All 5V pins supply the power for the Raspberry Pi.

  Best regards,
  Daniel

• 0
  
  Rvhu99999 January 22, 2019 18:41

  If I want to power the raspberry via external power. so I can also use the USB from the raspberry. Is it enough only to cut the 5v pin from amp?

  other question if I replace the amp+ with the amp2 can I then use the usb ports, external GPIO connections, LCD etc.  (using the 2A 5v  connected to the PI is working fine)

  But I don't want to trough out 55 euro of the AMP+ so if cutting the 5V pin will work i will try that first. (or to more pin need to be cut?)

• 0
  
  HiFiBerry team January 23, 2019 06:09

  Cutting all 5V pins on the Amp+ should work. However, you might dame the board with this as these pins aren't easily accessible.

  The Amp2 provides enough power for the Raspberry Pi 3B+ and the official display. If you have additional power-hungry USB devices, we can't guarantee it will work.

  Best regards,
  Daniel

• 0
  
  Rvhu99999 January 23, 2019 19:03

  Many thanks for your quick respond. Just to be sure, cutting pin 2 and 4 to raspberry pi will do. then connect the 5v to raspberry pi with separate power supply can be done. all other GPIO pins are supplied via the raspberry pi?