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Here are some instructions to use the Pirate Audio Headphone Amp (https://shop.pimoroni.com/products/pirate-audio-headphone-amp, PIM482) without any other software.

Sound

/boot/config.txt

Edit /boot/config.txt

sudo nano /boot/config.txt

Set up audio

Add this to the end of of the file:

# Pirate Audio
dtoverlay=hifiberry-dac
gpio=25=op,dh
dtparam=audio=off

(Note: The Pirate Audio Headphone Amp is not made by hifiberry, but the overlay works.)

If you are on Raspberry Pi Zero, depending on how you use the display, you may want to disable the Raspberry Pi Zero led:

# disable led
dtparam=act_led_trigger=none
dtparam=act_led_activelow=on

For other Raspberry Pi, please see: https://mlagerberg.gitbooks.io/raspberry-pi/content/5.2-leds.html.

Enable i2c and spi

You need to enable i2c and spi. You can do this via config.txt or using raspi-config. If you want to set this up while you're editing config.txt, look for the lines below and remove the # from i2c and spi:

# Uncomment some or all of these to enable the optional hardware interfaces
dtparam=i2c_arm=on
#dtparam=i2s=on
dtparam=spi=on

If you prefer to use raspi-config, boot your Raspberry Pi and type

sudo raspi-config

Edit asound.conf

Add this to asound.conf

pcm.!default  {
 type hw card 0
}
ctl.!default {
 type hw card 0
}
pcm.!default {
        type plug
        slave.pcm “softvol”
}
pcm.softvol {
        type softvol
        slave {
                pcm “dmix”
        }
        control {
                name “Amp”
                card 0
        }
        min_dB -5.0
        max_dB 20.0
        resolution 6
}

(Source: https://forums.pimoroni.com/t/volume-for-pirate-audio-headphone-amp-for-raspberry-pi/22058)

Screen and GPIO

Install required packages

As per usual, make sure you have the latest Raspian:

sudo apt update
sudo apt upgrade

Then:

sudo apt install python3-rpi.gpio python3-spidev python3-pip python3-pil python3-numpy
sudo pip3 install st7789

Using the GPIO

If you've not used the GPIO much, this script may be helpful:

Using the square display (240x240):

The get started with the square display, see st7789 Python library examples, such as:

Things to note

Turning the backlight off while the Pi is running

It's possible to turn the backlight of the display on/off. For example, with the above code, and disp initialised accordingly (disp = ST7789.ST7789(...)), the following command will turn off the backlight:

disp.set_backlight(0)

With the above libraries, it is not possible to dim the backlight. Hwoever, there are notes here on how this may be possible: pimoroni/st7789-python#8

Turning the backlight off when the Pi is powered down.

Note that when Pi is powered down, the backlight comes back on. The backlight is turned off by a low signal on the backlight pin. When the Pi shuts down that pin is likely going to a floating state (not a low), thus the backlight goes back on, see forum.

With the display configuration including BACKLIGHT=13, add the following text to /boot/config.txt:

dtoverlay=gpio-poweroff,gpiopin=13,active_low=1

This pulls the pin low for poweroff. It has the side effect that the Pi will no longer boot by pulling pins high. The documentation states that "Note that this will require the support of a custom dt-blob.bin to prevent a power-down during the boot process, and that a reboot will also cause the pin to go low." However, just making the above modification, the Pi does boot after power dis/re-connection.

(See overlays here.)