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Powering hifiberry amp+, PI2 and official 7" DSI display

Martin Schneider

December 03, 2015 21:37

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I would like to power my pi 2, my official raspberry dsi display and my hifiberry amp with only one single power supply. At the moment I have the DSI display connected to the GPIO Pins of the PI (5V & GND). I actually mean the GPIO pins of the hifiberry amp which extend the GPIO pins of the Pi in some kind of way.  

At the beginning everything seemed to work fine. The display was detected and the amp+ was also doing a great job. Some problems came up when I wanted to switch on/off the backlight of the display. Then the PI was crashing and rebooting sometimes when I tried to turn off the backlight. I realized that it is a power issue.

When switching on/off the display it comes to a loss of voltage or whatever. It seems that the display or the amp+ are not sufficiently powered although I have a 12V power supply with 6A. I tried different sorts of power supplies but it didn´t help. The amp seems to cut off the supply and seems to limit it to a certain level.

I don´t have any problems when I connect a second power supply to the micro usb input of the display. Switching on/off the display is working fine then.

Now I am wondering if there is any chance to power all my devices with on power supply.

Does anybody know how I could draw so much power (5V) from the hifiberry amp that the display is going to run stable?

 

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11 comments

• 0
  
  hifi December 04, 2015 00:00

  How do you switch backlight on/off? Some LCDs use GPIO pin #18 for that purpose. The same pin is used by HiFiBerry products. That's why there is conflict.

  Edited by hifi December 04, 2015 00:00
• 0
  
  HiFiBerry team December 04, 2015 05:51

  Hi Martin,

  as the Pi display is using quite a lot of power, this won't work stable. The Amp+ was not designed with a big additional power in mind. Increasing the power of your external power supply won't help as it is the voltage regulator on the Amp+ that limits the current. Therefore you will need a separate power supply for the display.

  Best regards
  Daniel

• 0
  
  Martin Schneider December 04, 2015 18:20

  Hi all,

  many thanks for the quick replies.  

  @hifi: I am not using GPIO #18. The display is connected to the DSI port of the pi and only powered by the 5V GPIO pin of the pi2.

  @Daniel: I was afraid to hear that. Is it possible to configure the voltage regulator on the amp by software? I do not care about loosing warranty :-)... I probably need only a tiny bit more of current, but I definitely do not want to damage the amp or pi with too much current.

  If it does not work, I will have to find another solution. Then I might buy a DC-DC converter which could draw power from the 12V power supply and convert the voltage from 12V into  5V. The 5V output of the converter could be connected to the 5V input pins of the display.

  At the same time I could connect the power supply directly to the power input (12V-18V) of the amp+ and  provide the amp with 12V. The converter and the amp+ would be connected in series then. What do you think about the idea? Any recommendations for a converter?

  Best, Martin

   

• 0
  
  HiFiBerry team December 04, 2015 18:26

  Unfortunately it is not possible to configure the regulator by software. You could just use a something like the LM7805 with a big heatsink to create an additional 5V power supply for the display.

  Best regards
  Daniel

• 0
  
  Martin Schneider December 04, 2015 20:54

  The LM7805 does not seem to be very energy-efficient. I think I am going to buy the TSR1-2450. It does not require a heatsink or any additional cooling. The TSR1-2450 is a little bit more expensive but it consumes less energy. What do you think? Can I use the TSR1-2450 to power the DSI display?

• 0
  
  HiFiBerry team December 08, 2015 09:54

  Yes, the LM7805 is not efficient. I just recommended it because it is cheap and you will get in in every electronics shop. The TSR1-2450 looks like it should work with the display. However, as I don't have tested this, I can't guarantee that it will work. However I see no reason why it shouldn't.

  Best regards
  Daniel

• 1
  
  Martin Schneider December 19, 2015 20:26

  I have just tested the TSR1-2450. It works fine for me. I can power the 7" DSI Display, the amp+ and PI with only a single 12V power supply. :-)

  Thanks for helping me... :-)

• 0
  
  Toby Wahn July 27, 2016 19:59

  Hi Martin, i have the same equip and the same problem. May you send me some pics how do you install the whole equip (especially the pins and the TSR1-2450)? Thank you (tobywahn85@web.de)

• 0
  
  Peter Eberle March 01, 2017 09:52

  Hi Toby, did you solve the problem? Would it be possible to get pictures or a simple plan how you power up the 3 boards and the display using the TSR1-2450 or LM7805? Thank you in advance. peli@aon.at

• 0
  
  Toby Wahn March 01, 2017 10:07

  Hi, yes i solved the problem. I have some pics/ details of the solution with my printed case on https://www.facebook.com/Ideas4Print/. More Informations (wiring sketch....)pls via facebook.
  kind regards

• 0
  
  Martin Schneider March 01, 2017 14:09

  Hi Peter & Toby,  you will find a simple plan on page 3 of the datasheet:

  http://www.tracopower.com/products/tsr1.pdf