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by Rasathus
Thu Dec 13, 2012 2:26 pm
Forum: Automation, sensing and robotics
Topic: Which webcam works best with debian?
Replies: 11
Views: 15259

Re: Which webcam works best with debian?

Ive been using a Microsoft Lifecam Cinema on my Monstrosity Rover , and haven't had too many troubles with compatibility. On connection, you'll notice a number of devices added, noted in the dmesg log. You should find you get a dev device for the camera itself, as well as the onboard microphones. So...
by Rasathus
Thu Dec 13, 2012 2:07 pm
Forum: Other projects
Topic: Text Star Serial LCD Display
Replies: 3
Views: 2015

Re: Text Star Serial LCD Display

The Textstar display is really nice, as you can just send it data as you would any other serial connection. So you can connect up your pos and neg to the 3.3v pin, and ground on the GPIO panel, and then connect you're tx/rx pins at 14 and 15, and you're done. I would suggest referring to the diagram...
by Rasathus
Fri Oct 12, 2012 12:38 pm
Forum: HATs and other add-ons
Topic: Current regulation circuit for Raspberry Pi Laptop
Replies: 0
Views: 895

Current regulation circuit for Raspberry Pi Laptop

Ive recently been building a Raspbery Pi Laptop, using a revision 2 Raspberry Pi, and have managed to get it all up and running ... http://rasathus.blogspot.com/2012/10/a-raspberry-pi-laptop-easy-way.html I notice in the documents about the revised board that there was a stipulation about ... 'but i...
by Rasathus
Fri Oct 12, 2012 11:10 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: 74HC595 Shift Register IC Vcc
Replies: 16
Views: 12621

Re: 74HC595 Shift Register IC Vcc

Ill get a proper list and diagram this evening, but for now the shopping list is something like this... 1x LD1117V33 3.3v Voltage Regulator To-220 package. 1x 1N4001 Diode 1x 10 µf Electrolytic Capacitor 1x 100 µf Electrolytic Capacitor and if you want a little power light, a 330ohm resistor and an ...
by Rasathus
Fri Oct 12, 2012 10:54 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Python components library, your thoughts ?
Replies: 0
Views: 510

Python components library, your thoughts ?

I've been working on writing a few IC and sensor implementations recently, and found that the community seemed quite well served with things like wiring pi and Raspi.GPIO, for dealing with low level pin and bus interaction. What I did notice however that there doesn't seem to be much in the way of c...
by Rasathus
Fri Oct 12, 2012 10:44 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: 74HC595 Shift Register IC Vcc
Replies: 16
Views: 12621

Re: 74HC595 Shift Register IC Vcc

I've been playing about with the 74HC595s recently, and resorted to building a little 3.3v supply from a voltage regulator and a 9v battery, and powering the ICs over that. http://4.bp.blogspot.com/-QHPSK_pWWEc/UGt2HeXpspI/AAAAAAAAALc/tag7i4bOQQs/s640/74HC595-usage.png I've been using the hardware S...
by Rasathus
Mon Oct 01, 2012 7:20 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

What sort of GPIO expander were you looking at ? I've been playing around with some 74HC595's, which i quite like as you can chain them all together, but im still ironing some bugs out of my implementation. I've also got some MCP23009's about, which i've been meaning to play with, they should be alo...
by Rasathus
Sun Sep 30, 2012 7:25 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

Joan, are you using a bench power supply ? Your readings look very steady compared to mine. Ive got a resistor divider setup like this ... +5V Sig --> 220 Ohm resister --> +3v Sig To Pi --> 330 Ohm -- > 0V But my readings dont look as stable as yours. Are those plots individual readings, or averaged...
by Rasathus
Thu Sep 27, 2012 11:45 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Do I need current limiting resistors for ICs ?
Replies: 6
Views: 2398

Re: Do I need current limiting resistors for ICs ?

Thankyou for the very comprehensive response.
by Rasathus
Thu Sep 27, 2012 4:29 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

So the real moral is "RTFM" :-) Ill rig it up on a 5v supply with some resistors, and see if i can come up with a reading to distance mapping curve for it.
by Rasathus
Thu Sep 27, 2012 11:22 am
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

For anyone interested in the results with the C implementation, I managed to get it all written up last night, with the post available here ...

http://rasathus.blogspot.co.uk/2012/09/ ... 05_27.html
by Rasathus
Thu Sep 27, 2012 11:21 am
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

If you we're to use an arduino clone, wouldn't you be better off interfacing with the sensor directly, and then relaying the results to the Pi, without the need to extend the pulses ? Once you had the accurate reading taken on the arduino, you could then send the data back over a serial or i2c conne...
by Rasathus
Thu Sep 27, 2012 12:07 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Do I need current limiting resistors for ICs ?
Replies: 6
Views: 2398

Re: Do I need current limiting resistors for ICs ?

Ok. Thanks for the clarification.
by Rasathus
Wed Sep 26, 2012 9:54 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Do I need current limiting resistors for ICs ?
Replies: 6
Views: 2398

Re: Do I need current limiting resistors for ICs ?

I was thinking more towards best practices. I've been running mcp3008's and 74HC595's without a problem, but I thought I should probably check if its something I should be doing.
by Rasathus
Wed Sep 26, 2012 9:41 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Do I need current limiting resistors for ICs ?
Replies: 6
Views: 2398

Do I need current limiting resistors for ICs ?

Im still rather new to the hardware side, and was wondering whether I need a current limiting resistor for ICs and other components, or whether this is limited to things like LEDs ?

Thanks
by Rasathus
Tue Sep 25, 2012 11:42 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

Hmm, looking at the pdf on the micropik site, its operation looks identical. Have you got a logic level convertor about ? It might be worth trying it at 5v, and see if you have any luck.
by Rasathus
Tue Sep 25, 2012 11:02 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

I've been hugely cavalier / fool hardy and connecte my vcc directly to the 3.3v breakout pin, and the same with each of the gpios. I haven't had a chance to try mine on 5v yet, but I'll try and make time to. I think there are a number of manufacturers carrying a sensor they refer to as an hy-srf05, ...
by Rasathus
Tue Sep 25, 2012 5:15 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

The code works wonderfully, I gathered some data for comparison last night, but haven't quite managed to finish the write up yet. I should get some time to do the comparisons tonight, and get an update posted.
by Rasathus
Mon Sep 24, 2012 10:04 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

Im currently working through modularising some of the snippets Jeremy and I have written, and package them up into a kind of component library. Kind of the next higher level than wiring pi, rather than worry about pins, you interact with components. Yeah, you may have a point. It may be educational,...
by Rasathus
Mon Sep 24, 2012 8:11 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

Sorry, that wasn't very clear. I meant you can't run a number like with i2c. You could only use two devices on the spi bus as you need a chip select, and the Raspberry Pi only has two chip selects. I think the Raspberry Pi only supports the Master/Slave based SPI, although I believe there are altern...
by Rasathus
Mon Sep 24, 2012 7:35 pm
Forum: Python
Topic: Smallest delay in Python????
Replies: 9
Views: 3567

Re: Smallest delay in Python????

Hi Matt134, did you make any progress with this ? I've been playing with an HY-SRF05 myself, and have a bit of a discussion going over on the Auotmation and sensing forum. http://www.raspberrypi.org/phpBB3/viewtopic.php?f=37&t=18291 I've got a basic implementation of it working in python. I've just ...
by Rasathus
Mon Sep 24, 2012 7:24 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

I've been using an mcp3008 over the spi bus for analogue input. Although you can only run one on the spi bus. it does give you 8 analogue inputs to play with, so its plenty for most projects. My concern about using the capacitors is mainly due to how long it may take to make a reading. At the moment...
by Rasathus
Mon Sep 24, 2012 4:42 pm
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Re: Ultra cheap ultrasonics, and a bit of a challenge

To cover the voltage question, I've actually been cheating and running this at 3.3v, and it has worked quite well. I have got some logic level convertors about, so it would probably make sense to set it up with 5v triggers etc. and compare the results. @raspberrypiguy1 , they appear to be part of a ...
by Rasathus
Mon Sep 24, 2012 9:59 am
Forum: Automation, sensing and robotics
Topic: Ultra cheap ultrasonics, and a bit of a challenge
Replies: 73
Views: 32516

Ultra cheap ultrasonics, and a bit of a challenge

I've recently been evaluating a number of different range finding sensors, for use in my monstrosity rover project. http://rasathus.blogspot.co.uk/2012/09/ultra-cheap-ultrasonics-with-hy-srf05.html Whilst researching I came across the incredibly cheap HY-SRF05 sensors, frequently used within arduino...
by Rasathus
Sat Sep 15, 2012 10:14 am
Forum: Automation, sensing and robotics
Topic: Robots with frick'in WiFi
Replies: 17
Views: 4771

Re: Robots with frick'in WiFi

Thanks for the suggestions. I'm currently rewritting monstrosity around a distance & degree based concept, which should be much less prone to latency issues. My main concern with alternative radio solutions is that I wouldn't be able to serve web pages directly from the rover, as I envisage having t...

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