Summary of DeCart
DeCart is a shopping-cart attachment that uses social pressure via lights, display, and sound to encourage productive, connected shopping behavior. The project combines an LCD, LEDs, speaker and amplifier, Bluetooth, sensors, and an Arduino, housed in a custom box, with careful wiring and testing of each component.
Parts used in the DeCart Project:
- Sparkfun Basic 16x2 Character LCD - White on Black 5V
- 11 x LED lights (1 red for selfishness, 10 yellow for progress bar)
- Speaker breakout board (Sparkfun breakout)
- Amplifier (Sparkfun amplifier)
- 8-ohm speaker
- BlueSMIRF Bluetooth modem (Sparkfun)
- Materials for enclosure (wood in this build)
- Arduino Mega 2560
- 1 x Piezo drum sensor
- 200 ohm resistors for LEDs
- Protoboard or makeshift Arduino shield for soldering circuitry and wiring
Description
DeCart is an attachment to a shopping cart that uses social pressure to make the shopping a more productive, connected experience for society as a whole.
List of Materials
Although the entire premise of the project is simple, the implementation, however, is not and requires a lot of patience and system building.
- LCD Display. For us, we used Sparkfun’s Basic 16×2 Character LCD – White on Black 5V. See https://www.sparkfun.com/products/709.
- 11 x LED lights. One to indicate selfishness (we used red), the other ten to indicate progress bar (we used yellow; colors are up to your discretion).
- Speaker circuitry and any 8-ohm speaker. Specifically, this breakout board https://www.sparkfun.com/products/11125 and amplifierhttps://www.sparkfun.com/products/11125.
- Bluetooth Modem – BlueSMIRF module from Sparkfun – https://www.sparkfun.com/products/12582.
- Materials needed to construct the box. In our case, we used simple wood.
- Arduino Mega 2560.
- 1x Piezo drum sensor.
Step by Step of our Build Process (Hardware)
Step 1: Familiarize yourself with the Circuitry!
Test each individual circuit and get a handle of the connections. For example, try turning on the LCD display, controlling the progress bar, flashing the selfish light, etc.
Step 2: Construct the Design!
See the roughDesign.DXF file. For us, we made our product by laser cutting wood.
Step 3: The Interface Components
Hot glue all the components that have slits for them! Example: the LCD display, speaker, and the LED lights. Make sure that they fit snugly in and they don’t protrude outwards.
Step 4: Wire them!
Each LED light needs to be connected in series to a 200 ohm resistor and not to mention that all their grounds need to be shared. For the LCD display and speaker, I would recommend using a protoboard. For me, I created a makeshift shield for the Arduino Mega, soldered on the speaker circuitry, and had all wires eventually lead into this board.
Read More: DeCart
- What is DeCart?
DeCart is an attachment for a shopping cart that uses social pressure via lights, display, and sound to influence shopping behavior. - What LCD was used in the project?
The project used Sparkfun's Basic 16x2 Character LCD - White on Black 5V. - How many LEDs are used and what are they for?
Eleven LEDs are used: one red to indicate selfishness and ten yellow to display a progress bar. - What audio components are required?
A speaker breakout board, an amplifier, and an 8-ohm speaker are used for audio output. - Which Bluetooth module does DeCart use?
DeCart uses the BlueSMIRF Bluetooth modem from Sparkfun. - Which microcontroller is used in the build?
The build uses an Arduino Mega 2560. - How should the LEDs be wired?
Each LED should be connected in series with a 200 ohm resistor and all LED grounds should be shared. - What is recommended for mounting interface components?
Hot glue components that fit into slits, such as the LCD, speaker, and LEDs, ensuring a snug fit without protrusion. - What is the suggested approach before full assembly?
Test each individual circuit (LCD, progress bar, selfish light, etc.) to understand connections before full integration. - How was the enclosure constructed in this project?
The team used laser-cut wood following a rough Design.DXF file to build the enclosure.
