ECE597 Fall2014 Ringing Servos
Embedded Linux Class by Mark A. Yoder
Team members: Mark Morrison, Peter Olejnik, Randy Turner
Contents
Grading Template
I'm using the following template to grade. Each slot is 10 points. 0 = Missing, 5=OK, 10=Wow!
00 Executive Summary 00 Installation Instructions 00 User Instructions 00 Highlights 00 Theory of Operation 00 Work Breakdown 00 Future Work 00 Conclusions 00 Demo 00 Late Comments: I'm looking forward to seeing this. Score: 10/100
(Inline Comment)
Executive Summary
The goal of the project at this moment is to use a cape that gives the BeagleBone usage of 32 PWM ports and to attach servo motors to it. The servo motors will then drive a mechanism that will ring bells of sorts. We have successfully used the PWM cape to drive a servo to a specified position using a shell script. This was more difficult than it was originally thought, because the cape uses I2C1 on the board, which is I2C2 in software, and because there were multiple other configurations we needed to change to set up the cape. We use a JavaScript program to output I2C messages to the cape to control the servos. The servos are connected to a mechanism with two bells, and when the servo rotates the bells ring. The bells do not require a great amount of movement to ring, but need to be oriented correctly to get the best sound, so the program only moves the servo about 15 degrees away from the center in either direction. From this, we have learned that JavaScript was a poor choice for a project as time-sensitive as this. The asynchronous nature of the language has made it all-but impossible to control timing when using multiple threads. For this reason, we have begun the process of porting our software to C.
Give two sentence intro to the project.
Give two sentences telling what works.
Give two sentences telling what isn't working.
End with a two sentence conclusion.
The sentence count is approximate and only to give an idea of the expected length.
Hardware
Mechanical Hardware
Two diffrent types of servos were used. These were used with simmilar results.
The following quantaties of fasterners were used as well. All were obtained from McMaster-Carr
- X2 per Servo Mount 10-24 X 3/4" Nylon Shoulder Screw
- X2 per Servo Mount 4-40 X 3/16" Screw
- X5 per Servo Mount, X16 per Rack 2-56 X 1/2" Screw
- X2 per Servo Mount 2-56 Nyloc Nut
The bells used are bells provided to us by Dr. Yoder, orriginating from Hobby Lobby.
To build the Servo Mount, pieces were cut out from acrylic sheets. The links lead to DXF files. To download, rightclick and click save link as.
- X2 @ 0.125 Bell_Twist.DXF
- X1 @ 0.125 Servo_Connection.DXF
- X1 @ 0.25 Base.DXF
- X4 @ 0.25 and X2 @ 0.125 Spacer.DXF
To build the Mounting Racks, pieces were cut out from acrylic sheets. The links lead to DXF files. To download, rightclick and click save link as.
- X1 @ 0.125 LowerRack.DXF
- X1 @ 0.25 TopRack.DXF
- X16 @ 0.125 Latch.DXF
Electrical Hardware
To drive all these the following cape was used:
The electrical circitry for the detector was made a few components. Additional components may be needed if you don't want to make perminant additions to the cape.
Each detector comprises of:
Mechanical Assembly
Servo Mount Assembly
Rack Holder Assembly
Electrical Assembly
Other Stuff....cause work in progress
- Project materials are at https://github.com/randman2011/ECE597-RingingBells. Clone the repository to find a read-me and code to get started.
- Use a PWM Cape to expand the PWM functionality of the Beaglebone.
- Attach bells to the servos so they will ring with minimal servo movement.
- Run the "RingerScript.js" program.
Give step by step instructions on how to install your project.
- The GitHub repository containing all of our software can be located here: https://github.com/randman2011/ECE597-RingingBells.
- Be sure your README.md is includes an up-to-date and clear description of your project so that someone who comes across you git repository can quickly learn what you did and how they can reproduce it.
- Include a Makefile for you code.
- Include any additional packages installed via opkg.
- If there is extra hardware needed, include links to where it can be obtained.
User Instructions
Once everything is installed, how do you use the program? Give details here, so if you have a long user manual, link to it here.
Highlights
Here is where you brag about what your project can do.
Include a YouTube demo.
Theory of Operation
Give a high level overview of the structure of your software. Are you using GStreamer? Show a diagram of the pipeline. Are you running multiple tasks? Show what they do and how they interact.
Work Breakdown
While we all took part in all the components, each one of us took lead in a particular field:
- Mark took lead in desinging the electrical hardware.
- Peter was the brainchild behind the physical mounts and the mechanical design.
- Randy was the architect of the software that drove the bells and servos.
Future Work
- The current I/O being used is using an IR detector and IR LED. The detection range of our set up is not that long. It would be intresting to see an improvement on this scheme.
- Other hardware inputs could also be looked at, from as simple as push buttons to a Rube Goldberg like contraption.
- In addition to hardware inputs, software inputs of various type could be looked at. These wern't looked at as deeply as we would have liked to, due to the limitation of time. A great suggestion would be to use Crontab.
Conclusions
Give some concluding thoughts about the project. Suggest some future additions that could make it even more interesting.
Stuff we found (Cause stuff is dumbz)
- i2c1=i2c2
- i2c2=i2c1
- i2c0=???
- i2cdetect -y -r 2 finds address 0x40 and 0x41
- need to set mode register (register 0x00) to not sleep mode to use the internal oscillator
Embedded Linux Class by Mark A. Yoder