Giant Guitar Tuner

Software components to support the operation of a giant guitar tuner display. See src/main.c for a fuller description of the software architecture.

Setup and Installation

• Using Raspberry Pi Imager, choose the Raspberry Pi OS Lite image and select the SD card, click Write.
• Mount the boot drive and make the following changes to config.txt:
  • Comment out dtparam=audio=on
  • Add

  disable_splash=1
  dtoverlay=disable-bt
  dtoverlay=sd_overclock=100
  boot_delay=0
  dtoverlay=gpio-shutdown
  

• Unmount and remove the SD card.
• Boot the raspi (press enter if it seems to hang at "Update UTMP about System Runlevel Changes.")
• Default username/password: pi/raspberry

Configure the Pi.

sudo raspi-config

• Localization, WLAN Country - US
• Localization, Timezone - US, Eastern
• Locatization, Keyboard - English (US), Other.
• System, Wireless LAN (configure to allow installing packages and transferring application code).
• System, Network at Boot (disable to speed bootup).
• Interface, SSH (enables SFTP and SSH console).
• Interface, Serial Port (enable to allow console access over pins 6 GND, 8 TX, 10 RX).
• Finish

Ensure apt-get has the latest versions and install them.

sudo apt-get update
sudo apt-get upgrade -y

Install Git, cmake, pigpio.

sudo apt-get install git cmake pigpio -y

Install Application

git clone https://github.com/czema/guitar-tuner
cd guitar-tuner
sudo ./configure.sh
sudo ./compile.sh
cd bin
./guitar-tuner

It should say something like "SPI: FT4222 SPI Slave OK, Running."

Press Ctrl+C to close the program.

To start the application as a service, run sudo ./install.sh

Hardware Notes

https://pinout.xyz/

Pin #02 - 5V
Pin #05 - GPIO3 (active low, power on/off)
Pin #06 - GND (power on/off)
Pin #08 - TX (serial console)
Pin #09 - GND (serial console)
Pin #10 - RX (serial console)
Pin #12 - GPIO18 (PWM LED data)
Pin #14 - GND (LED)
Pin #16 - GPIO23 (Input, Motion Sensor)
Pin #18 - GPIO24 (Output, Relay - power supply)

Generic Raspberry Pi Notes

• To resize the serial console terminal, nano .profile and add:

  if [[ "$(tty)" != "/dev/tty1" ]] ; then
        stty rows 60 cols 160
  fi

• The gpio-shutdown dtoverlay (in config.txt) allows connecting GPIO 3 to GND to safely shut down the computer. The rpi comes pre-configured to allow GPIO 3 to GND to power up the computer.