Product Design Specification
Digital Level PDS (Google Doc)
Miguel Garcia, Sabin Maharjan, Christina Nelson, Calhoun Zabel
Version 2.0
October 26, 2015
1. Introduction
This project is to design a Digital Level in order to measure and indicate a level surface. Analog level indicators use a liquid bubble to indicate the inclination of the surface, while this digital level uses 17 LEDs arranged on two axes. These LEDs are controlled by a microcontroller using input from a 3 axis accelerometer. Depending on the inclination of the surface, different LEDs will be illuminated.
2. Constraints
- Have one or more inputs or sensors
- Have one or more outputs or transducers
- Have a digital processor
- Use a two layer PCB that is between 9 and 900 cm^2, with no side of the board being less than 2 cm or more than 30 cm
- Use components that can be hand soldered in a crude reflow oven (no BGAs, uBGAs, LGAs, or components smaller than 0603 packages allowed)
- Include the "Must," "Should," and "May" specifications in the class handout
3. Function
The digital level will measure the inclination of a flat surface using a 3 axis accelerometer however, only the x and y axes will be used to detect the orientation. The accelerometer will measure a range from 0 - 90˚ inclination where 0˚ is the green LED, 10 - 20˚ is the yellow LED, 30˚ is the orange LED, and 40˚+ is the red LED as shown in the figure in the corner. The digital level will implement 17 LEDs in the shape of a cross. These are displayed on the top of the digital level. The user will place the digital level on a surface and based on the angle of inclination, the LEDs will display their respective color. If the surface is completely flat, the middle LED will light up green.
4. Components
The digital level will have 4 major components. The Xtrinsic FXLN8371Q 3-Axis Low-Power Analog-Output accelerometer, Atmel ATmega328P 8-bit microcontroller, two 8-channel demultiplexers, and LEDs.
5. Size
The digital level will be housed in a 3D printed design, no smaller than 4" x 4". The size and weight should be lightweight and shall allow portability, by a single user, when required to be moved.
6. Manufacturability
The digital level must be manufactured on a circuit board with area between 9 cm to 900 cm. The digital level will be manufactured by using two-layer printed circuit board technology and shall contain at least 25% surface mount components. The design will incorporate components that can be purchased through DigiKey.
7. Materials
The housing will be made of a material that can be produced using additive manufacturing technology. Any materials used in the housing design shall be non-toxic, water-resistant, shock-proof, and highly durable.
8. Aesthetics
The digital level will implement brilliant and colorful LEDs in four different colors: green, yellow, orange, and red. The housing of the digital level shall have the look and feel of a professional measurement device.
9. Ergonomics
The shape of the housing should be designed so that the user can hold it comfortably in his/her hands. The design must be void of any sharp, protruding corners and edges.
10. Cost
The target cost for the digital level is approximately 50 US dollars. This cost reflects the high quality materials in the design.
11. Safety
The digital level shall be powered by batteries, operate at safe voltage levels, and function silently. The housing should remain cool to the touch and shall include no small parts that could be choking hazards.