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3.3 Sensor Board with Hole

This module detects a users finger position on the surface by sensing a capacitance change (like SmartSkin [9]). A finger touch changes the capacitance of the metal pads, which are set on the surface of the top board. This module enables users to input by finger touching and tracing the surface. Four pads seen around the hole are connected horizontally and vertically, enabling the system to detect a coordinate position of the finger, as shown by the arrows in Fig. 3. This module looks for a capacitance change by cross-sensing: vertical and horizontal position sensing. Each hole on this board is connected to both the solid state relay and voltage sensing module.

3.4 Solid State Relay Board

The Solid State Relay Board is placed in the bottom physical layer of the Visible Breadboard Device (Fig. 2). This module (Fig. 4) has 60 solid state relays placed between the 36 holes connected to the Sensor Board. By switching these solid state relays ON / OFF, the connection status of the holes is changed dynamically. Active solid state relays form the wiring between the holes and complete a circuit with the electronic materials inserted into the Sensor Board.

Fig. 3. Top view of Visible Breadboard device

Fig. 4. SSR board on bottom layer of Visible Breadboard device

These solid state relays are controlled by eight shift registers. The shift registers are controlled by a micro controller with serial connections.

3.5 Drive Sensing Voltage of Each Hole

This module (Fig. 5) measures the voltage value of the 36 points. The drive control of the solid state relays enables switching the connection of the micro-controller AD converter

Fig. 5. Drive sensing module by SSR in bottom layer. ( close-up )

Fig. 6. LED displaying modules ( with opening top board)

and the holes of the Sensor Board into which the users inserts the electronic materials. Though this module can measure only six points at once, we think that it is sufficient for this device because the full-color LED system (showing the voltage in color) in this device is lighted by the drive control system (six LEDs at once).

3.6 Displaying The Voltage

User can choose the start voltage color and the end voltage color in the configuration mode. This module (Fig. 6) changes its LED color by gradation corresponding to the voltage value (Fig. 7). The color is determined by Equation (1).

3.7 Hardware Specification of the Visible Breadboard Device

The hardware specification of the Visible Breadboard Device is shown in Table 2. We developed four Visible Breadboard Devices. They can be connected to each other to make 144 holes available. There is a resistance value between the holes because this device uses Solid State Relays for the wiring. However, this is an allowable margin error for the circuits that can be built on this hardware. The distance between two holes is approximately 12 times larger than found on an ordinary solderless breadboard. This is large, but allows users to use extensions (Fig.7) for small electronic materials or IC chips.

Table 2. Hardware Specification

weight

1200g

size

24.2cm (W) 24.2cm (L) 6cm (H)

number of holes

36holes

distance between 2holes

3.2cm

voltage sampling frequency

30Hz

AD Converter

1024 steps (05V)

LED Color steps

RGB Color 8096 steps

Micro-controler

Atmega1028 (ArduinoMEGA)

Clock

16MHz

Input Voltage

0-5V

with Optional OPAMP max voltage 48V

Resistance value between holes

2Ω

Fig. 7. Parts extension for Visible Breadboard device ( wire with socket )

 
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