TOUCH TO ROLL: A Decoder-Based Dice

Electronic dice, or e-dice, are widely used today, but creating a design replicating the anticipation and randomness of a physical dice roll comes with its challenges.

- DR GEETALI SAHA AND PRIYANSHU PATEL

This device achieves that effect by generating a rolling motion that lasts approximately four seconds, though the duration can be adjusted by modifying the rolling steps.

A 3-to-8 decoder (IC 74LS138) displays a valid dice face, with combinational AOI logic (AND, OR, and INVERT gates) ensuring only valid outputs. Seven individual LEDs, arranged to represent numbers 1 through 6, replicate the appearance of a traditional dice. The ESP32 microcontroller brings the design to life, handling random number selection and creating a realistic rolling effect, making this an excellent case study in digital circuit design.

Fig. 1 shows the prototype with the rolling clock, while Fig. 2 presents a block diagram of the system. Table 1 lists the components required to build this device.

The main components of this device are the ESP32 board and the ICs 74LS138, 74LS260, 74LS04, and CD4075. The truth table for the decoder IC 74LS138 is provided in Table 2.

The ESP32 board is the core of the device. It is used for the following tasks:

Detecting the closure of the path that activates the dice roll.

Introducing a rolling step of a few seconds (four seconds in this case).

Generating a 3-bit random number.