An Intermediate Dive

So, you’d like to learn more about the tech behind the OnePSG. Let’s consider each of the different aspects of the instrument.

Underside of a traditional pedal steel guitar’s body.

Body:

  • For the prototypes we basically copied the design of a traditional pedal steel guitar (TPSG) body, essentially an upside down U shape to house the parts and components that make it all work.

Mechanical:

  • A very few mechanical parts remain unchanged in the OnePSG design: neck, nut, tuners, pedals, knee levers.

  • The bridge of a TPSG is a complicated assembly of parts. The OnePSG has a simple bridge, like that of a standard guitar or lap steel guitar.

Control PCB in the Alpha Prototype

Electronic:

  • Control PCB: The Control (aka Main) PCB (printed circuit board) is the heart, or rather the brains, of the OnePSG. It takes inputs from the pickups, and pedal and lever sensors. It also houses a one main microcontroller (MCU) and several digital signal processing (DSP) MCUs.

  • Pickups: There are ten or twelve single string magnetic pickups. Like any magnetic pickup, each pickup (one per string) captures the string’s vibration.

  • Codecs: The pickups’ signals are converted by codecs into digital audio signals which are then pitch-shifted in real-time by the DSP MCUs. After processing, the digital signal for each string is converted by the codec back to an analog signal for final output to a guitar amp, for example.

  • Pedal/lever PCBs: There are ten small PCBs, one for each pedal and lever to capture the pedal or lever movement.

Software:

  • There are two main types of software running on the board. The DSP MCUs run signal processing code along with handling communication with the Control MCU.

  • The Control MCU’s code handles a number of different tasks:

    • Accept values from the pedal and lever sensors

    • Use those values to calculate how much each string’s pitch should change.

    • Communicate with the DSP MCUs: tell them what to do with the string signals and, in the case of tuning, receive the physical pitch of the string to display to the player (like any electronic tuner).

    • Handle stored data; e.g., saved copedents, saved tone profiles, etc.

    • User Interface (see below)

  • The DSP MCUs code takes the digitized audio signals from the codecs and pitch-shifts them based on the communication from the Main MCU.

User Interface:

  • A touchscreen is incorporated into the OnePSG. It is used by the pedal steel player to edit or create copedents, save and recall copedents, switch between copedents instantly, use the electronic tuner, change tone profiles, etc.