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GPIO usage HifiBerrry Amp+

Benjamin LECOQ

March 12, 2015 10:01

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Hi,

i've just bought an HifiBerry Amp+ and running it on Raspberry Pi 2.
I will need to connect the Amp+ via a breadboard for a project because I will need to plug several device on the GPIO port.
I want to connect HifiBerry Amp+ and Pimoroni Dot3k LCD screen.

I'm wondering what his mean exactly:
"GPIO2-3 are used by our products for configuration."

Does it mean that once you've installed/configured Amp+ on your raspberry you don't need to connect these GPIO anymore between Amp+ and Raspberry?

In other words: Which GPIO pins do i need to connect between AMP+ and RPI via my Breadboard in order to make it work?
GPIO 2, 3, 18, 21 or only GPIO 18 & 21 ?

Thanks

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8 comments

• 0
  
  HiFiBerry team March 12, 2015 13:17

  You need all, 2,3 and 18-21 (not 18 and 21). Note that long cables might introduce problems as the frequencies can be quite high.
  
  Best regards
  Daniel
• 0
  
  Benjamin LECOQ March 12, 2015 14:54

  What do you mean by 18 OR 21?
  You can choose which one to use? If so how can I achieve this ?
  I'm asking you because the other device i want to use need GPIO 18.
  Thanks
• 0
  
  HiFiBerry team March 12, 2015 17:07

  No, 18,19,20 and 21 are reserved for the sound interface. You can't use them for anything else.
  
  Best regards
  Daniel
• 0
  
  armyofmike March 19, 2015 16:11

  Greetings,
  
  I recently purchased the Amp+ and wish to set up the following:
  
  - Volumio running on Pi 2
  - Amp+
  - With 16x2 LCD (adafruit)
  
  Benjamin seems to have at least a basic idea of how to go about this, but I'm a complete noob when it comes to the GPIO pins, breakout boards, etc. Are there any resources available that spell out the best way to approach this sort of setup?
  
  Thanks,
  Mike
• 0
  
  inonoob March 19, 2015 17:04

  Hey
  
  I think the best solution for LCDs is using I2C connection. I made it work with the Hifi-digi but it think it will work with Hifi-amp and Hifi-dac.
  
  Take a look at this thread:
  
  https://www.hifiberry.com/forums/topic/rpi2-digi-lcd-hd44780/
  
  Greeting from China
  
  Ino
• 0
  
  armyofmike March 19, 2015 17:40

  Thanks, inonoob.
  
  Looking at the page you referenced, your handle doesn't lend enough credit to your experience level!
  
  When you talk about using the I2C connection, are you doing all of this on a breadboard? I'm having trouble visualizing how I would wire this up without one.
• 0
  
  inonoob March 20, 2015 01:11

  Hey
  
  you can use this board:
  
  http://www.aliexpress.com/store/product/Original-Raspberry-Pi-B-GPIO-Multiplexing-Expansion-Board-Multiplex-Extend-Module-IO-Multiplex-Plate-Free-Shipping/1534002_32240229454.html
  
  On my Raspberry pi B, I used this board to have the Digi and my LCD working with the GPIO settings without a breadboard:
  
  http://www.modmypi.com/raspberry-pi/breakout-boards/piborg/piborg-triborg-gpio-triple-header-stacker
  
  So I never had problems with GPIO breakouts. I only use breadboard for debugging.
  
  I would defently go for I2C for LCD on Raspberry pi:
  
  
  
  as you can see only 4 wire are needed to wire the LCD's to the Pi.
  
  
  Ino
• 0
  
  armyofmike March 20, 2015 15:09

  This is outstanding, thank you so much for the info. Makes much more sense now.