Nuts and Volts - September/October 2018

navigated and edited. The approach taken here uses a Value Navigation Table.

Figure 17 shows part of the display. The characters on the display are either background or part of value blocks. The background characters are held in EEPROM and are used as the basis of the display. The value blocks contain overlaid values.

Values are held in a data structure as integers. The Value Navigation Table contains information about the location and size of each value block, and the navigation between blocks.

Much code is written to translate raw integer values into different displayed types (whole number,

percentage, time, note name, on/off blob, etc.).

Values are edited using increment and decrement buttons, with the step size depending on the duration of the button press.

Figure 18 shows song 1 with the verse selected. The position is 0 seconds, the duration is 29. 7 seconds, and track 2 is enabled for playback.

In Performance mode, the LCD digit size is made large by using custom characters and a ROM-based character map.

Seamless Transitions — The Smooth Operator

Foot-switch presses don’t change a song section immediately. Rather, they tell the Box that after the current section is finished playing, The sections are either looped or normal (not looped). When a looped section ends, it will either loop again, or if there is a pending section change, playback will hop to the new section. Normal sections will either stop when the end is reached or hop to a pending section change.

This makes operating the Box in Performance mode extremely simple. The only thing to worry about is telling the Box which section to go to next. You can tell it at any convenient point during the currently playing section.