April 8, 2011

CPE 322 Camera Level Indicator – HW7

Thomas Dabay, Kris Engel, David Quirk

4/8/2011

I pledge my honor that I have abided by the Stevens Honor System

The Group

The group will consist of three members. David Quirk will be the group leader and is currently a 4 out of 5 CPE major. For this particular report, David’s responsibilities will be to provide a software block diagram.

Kris Engel is a 4 out of 5 CPE major and will focus on the microcontroller programming portion of the project.For this particular report, Kris will provide a description of the hardware block diagram and put together this report.

Thomas Dabay is a 4 out of 5 EE major and will focus on any electrical aspects of the project including the wiring of fiber optics and any circuitry associated with the microcontroller. For this particular report, Thomas provided the hardware block diagram summary.

Preface

The group has provided two flowcharts, one software and one hardware specific. The hardware flowchart is color coded; providing insights into which specific hardware piece performs which functions and the way that they interact. The software chart is updated slightly and a more step-by-step description is provided.

Hardware Block Diagram

The hardware components remain at rest until the hot shoe port is activated. The hot shoe port is triggered by pressing the shutter button on the camera either half way or fully. Once the hot shoe is active, a signal is sent into the microprocessor’s input. This will trigger a function within the coding to activate the gyroscope. The gyroscope will begin to take readings. The product will detect the camera’s orientation along the Y axis on an XYZ plane. The gyroscope will then actively send a reading to the microprocessor. The gyroscope will continue to take readings, but the microprocessor ignores these until the current results are processed. The software will compare these readings to a hard coded “level” value. That is, several values are already programmed in which will make the microprocessor think the camera is level. By comparing the readings to these values, the microprocessor will determine in which way the camera is tilted or if it is level. The microprocessor will then send out a signal to three LEDs located within the viewfinder as shown below.

P1 will indicate the camera is tilted left, P2 indicates the camera is level and P3 indicates the camera is tilted right. The microprocessor will then see if the hot shoe is still giving a signal. If not, the picture has most likely been taken. If so, that means the user is still positioning the camera. If it is inactive, the microprocessor will tell the gyroscope to cease taking readings and will then go into sleep mode. If it is active, the microprocessor will take the latest readings from the gyroscope and repeat this entire process.

Software Block Diagram

Most of the description here is provided in the hardware portion. Most of the coding is based on loops and comparing real time values with pre-coded values and deciding which port to output a signal to.

Hardware

The following schematic is provided by sparkfun.com and shows the processor which has been chosen to be used for the project (a larger image will be attached to the homework for better viewing).

The Arduino Mini runs at 8MHz with an external resonator. It is a low voltage board that is perfect for powering devices such as a gyroscope. It has a USB connection to program the board and has a 150mA output. It’s most important feature is its size, at .7x1.3” it is among the smallest boards available, which is one of the group’s biggest constraints in choosing hardware. It also weighs less than 2g, which won’t add much to the weight of the camera.

The Arduino platform itself is very popular amongst the tech community and is used in many DIY projects and products. These products vary widely and the Arduino is considered to be a revolution in open sourced hardware. Its platform for coding and interface is very easy to use and robust.

SWOT

Strengths – The product is needed in the market, no other products provide the convenience of the group’s proposed product. The product is cost effective and would be cheap enough on a production scale to sell at a reasonable price for both serious and above average camera users. The group has decided to do the initial calibration at the factory, eliminating potential user error in calibrating the device. The flowcharts are cohesive and provide an accurate insight as to how the product works.

Weaknesses – For the particular camera the group is aiming to fit this device, there could be a problem trying to fit the device on top of the camera. The camera has a pop-up flash which only allows about three quarters of an inch of space to situate a microcontroller on top of. The product will need an external source of power.

Opportunities – The hot shoe can provide a signal that activates the product, which will cut down on power consumption.

Threat –If the hot shoe pass through cannot be executed, other accessories cannot be used. This may also cause deteriorated flash output.

Bibliography

1 / Camera Level Indicator – Hardware Description| Thomas Dabay, Kris Engel, David Quirk