help on DC-AC inverter for Public art Project. Thks

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Viking
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Post by Viking » Wed Aug 27, 2008 4:27 am

Hello Federico,

Just a thought about Goal 2 – shadow tracking. If each panel had a handful of photo sensors fitted evenly across its surface, so that the display as a whole would have about 100 sensors evenly distributed. The display would thus become a simple compound eye. The control PC could scan the sensor array at intervals and would thus be able to ‘see’ the shadows cast on it. Even more interestingly, it would be able to ‘see’ the ink drop and react to it. Thus a simple feedback loop would be set up.

Goal 3 – There should be enough pixel resolution to turn the display into a clock display with animated hands, etc.

Regards
Rob
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dyarker
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Post by dyarker » Wed Aug 27, 2008 6:46 am

(all following is my opinion, I don’t like typing “I thinkâ€
Dale Y

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Post by federico muelas » Wed Aug 27, 2008 9:26 am

Hi guys,
Thanks!

Rob,

I was considering installing light sensors on the panels too, but I think there are several factors that make the camera solution more suitable.

Firstly, the wiring; even if it were possible to use the same PICs we are using to control the pixels we would have to make the RS485 line bidirectional, right? If we use different PICs to read the sensors then we would have to put another line.

Secondly; on the renders only the shadow of the building itself is being shown but other elements such as trees, clouds or streetlights could also cast a shadow. In order to get this more complex shadows we need the definition that a camera can provide.

Thirdly; since we would have to extract the shadow of the building from the busy video image as much visual information would be need it, so color may be also a value to consider

fourthly; if possible, the image of the video camera pointing at the screen could be use as another system to remotely monitor the piece (and may be show it on the web page for the people to see).

The video feeding where we are getting the shadow of the building from will have three components overlapped that need to be filtered. One, the shadow of the building itself (that we need to extract). Two, the projected image of the ink expanding, and three the rendered image of the ink created by the screen. With the light sensor method we would get rid of this last one.

Most of the time the piece will be on the Art mode (ink on water), but since this is the School of Architecture the students will be able to show once in a while their low-resolution creations. It’ll be interesting to see what they do.

Dyaker,

You’re right, 3,740 no 3,700, I have to stop rounding off numbers at this point or I’ll order the wrong quantity of components.
I’m trying to get the School of Engineering, CS department at New Mexico University (http://www.cs.unm.edu/) involved in the project to do some work. Let’s see what they have to say and what parts they could help with and I let you guys know.

The most important thing is that pretty soon we will have a fully functional prototype that we will be able to show and base the future work on.

Whatever help you think we can get from the CS department at UNM please let me know. The University is really enthusiastic about the project and willing to help in whatever we need.

Good idea about the RS-232 card. The Ink Projector will incorporate its own independent system. The PIC will control all the necessary parts (water valves, pumps, lights) and monitor its functioning feeding some info to the computer for remote controlling and monitoring. This part will be pretty straightforward I think, I have done some of this for previous pieces (“Dripping Soundsâ€

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Viking
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Post by Viking » Wed Aug 27, 2008 11:32 am

Hello Federico,

Yes, you are probably right that the camera is the best option. It gives you the opportunity of having a ‘Blue Flower’ webcam sight. And it allows you to check it for maintenance. If you can control it remotely, you can log in, run a test pattern and observe the results live.
If we went for the photo-sensor approach, it would probably be a separate system with its own cable and PCB’s. Incidentally, RS485 is a bi-directional interface, but it would be easier to have a separate circuit.

I have just been speaking to my brother (unfortunately he had to rush out again, so I need to see him again tomorrow). So hopefully he will start/complete the detailed PIC programming in the next few weeks.
I will be travelling in the Philippians and Singapore from next Monday and will arrive back on the 14th. I will still have internet access but responses may be a little slower and more erratic during this time.

Regarding help from the university, there is a colossal amount of work in this project, just in it’s construction. There are about 135 circuit boards to construct, and fit into the panels. Then the panels themselves have to be fabricated and assembled. So there is plenty of work here.

I still want to construct a ‘data’ simulator test box, which should be useful for in-the-field-testing. It would allow you to test panels and/or whole displays, without the need of a PC. I will probably have to make a test circuit of the PIC part of this to facilitate software debugging the PIC code. So I need a way of generating the complete data string at will, and thus the need to construct this.

Regards
Rob
LIFE….the crappy bit between birth and death

federico muelas
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Post by federico muelas » Wed Aug 27, 2008 12:29 pm

Hi Rob,
I didn’t think of the running the test remotely but it’s a great idea.
Thanks a lot to your brother too!!
Philippians and Singapore whoa, I hope is a holiday and not a business trip. When you come back hopefully I’ll have the prototype up and ready, I’ll keep you posted. Actually I’ll make two units of the circuit you made of the module with the pic and send you one so you can test it too.

I think they decided to make Ranger2 totally free quite recently, still on the installation documentations it says that you have to register the copy, but in the actual software you don’t.
I hope the NM university will help with the assemblage of the panels, for the boards I’ll try to get few of my students as interns, let’s see.
The simulator test box would be a terrific idea! So we can test the panels as they are being built and then installed on the wall (something as simple as a disconnected cable can be a nightmare once the panels are up). Let me know what parts you need and I get them for you or reimburse the expenses. Let me know if you want to use the CNC for this too and I’ll send you the board.
Thanks thanks thanks!!
Fede

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Viking
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Post by Viking » Wed Aug 27, 2008 9:52 pm

Hello Federico,
No I'm afraid it is business. So I will be wandering around a TI wafer fab facility in a bunny suit for the next week, not much of a holiday I'm afraid.
I could use your CNC PCB making facility for the one-off test unit. I will see if it is quicker to hand build it or to spend the extra time laying out a PCB layout for it.

Regards
Rob
LIFE….the crappy bit between birth and death

federico muelas
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Post by federico muelas » Thu Aug 28, 2008 6:34 am

It sounds pretty interesting though. Just let me know if you want me to make any circuit on the CNC and you'll have it there when you're back.
Thanks a lot and have a productive trip
Fede

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Viking
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Post by Viking » Thu Aug 28, 2008 12:39 pm

Hello Federico,

It can be interesting. Some of the wafer fab plants are massive, production halls so large you need binoculars to see someone on the other side of the room.
I will concentrate on getting the PIC working and building the tester and other support circuitry needed to the PIC. This will be my goal for September

Regards
Rob
LIFE….the crappy bit between birth and death

federico muelas
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Post by federico muelas » Thu Aug 28, 2008 2:54 pm

thank you so much!!!!
Fede

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Viking
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Post by Viking » Mon Sep 01, 2008 4:19 am

Hello Federico,

I'm just off now on my trip, waiting for the taxi to turn up.
I've produced the code for the EPROM that will run the signal simulator. I have a design for the simulator, which I will build on my return. Brother is looking at the coding for the PIC. I've almost completed the PCB layout for the extension boards (the ones that do not have PIC's) and have also reorganised the main board to make the layout more compact and the pixel outputs sequential. I think that's about it.

Have you had any luck with the CNC machine cutting the test layout I sent you?

Regards
Rob
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federico muelas
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Post by federico muelas » Mon Sep 01, 2008 6:00 am

Hi Rob,
Thank you thank you so so MUCH!! You're great!
Say thanks to your brother too!
We are setting up a new more precise CNC machine, the old one it may not have enough definition, so this Wednesday we will give it the first try. They work with Eagle Cad software directly connected to the machine so at the moment I'm putting the Gerber file into this program.

Once I have the PCB made do you recommend me to put the circuit together to try it or should i wait until you have the reorganized one?

Have a wonderful trip!,( I hope you don't get a Kid by your side on the plane, I have a three years old and I know how hard an over an 8 Hours trip can be with one of those around).
Fede

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Viking
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Post by Viking » Tue Sep 02, 2008 12:26 am

Hello Federico,

Just checked in to my hotel in Singapore.
If I send you the gerber files for the extender board (the one without the PIC), this will be the final design (hopefully) for that board, so you can build and test one. And you will be able to experiment with the CNC machine at the same time.
I will try and send by Wednesday.

Regards
Rob
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federico muelas
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Post by federico muelas » Tue Sep 02, 2008 4:34 am

thanks a lot!
I hope you have at least some tome to walk around the city. It has to be amazing!
Fede

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Post by federico muelas » Thu Sep 04, 2008 2:59 pm

Hi Rob,
I hope you're having a nice trip.
After trying on the cnc we don't think we are getting the precision we need on the boards. This Tormach is a new piece of equipment they got at the School of Visual Arts where I teach and they haven't figure out the "right" way to do it yet.
So I decide to use some PCB manufacturer to do at least the board for the prototype.
Do you have any company that you specially recommend?
thanks a lot Rob!
Fede

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Viking
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Post by Viking » Fri Sep 05, 2008 4:38 pm

Hello Federico,

Good morning from Clark, Philippines (ex Clark Airforce base)

If you are intending to use a PCB manufacturer, then they will be able to do double sided boards. All the designs I have sent you have assumed it would be single sided, so there are wire links on the component side. Obviously it would be cheaper to have the board single sided, so if you go with this option, then you can use the designs as-is. However if double sided, then it would be best to re-design for double sided.

I have never had to have boards made your side of the pond, so I could not recommend anyone. I sure however, that someone on this board will know the best ones.

(Added later) You will have two main costs if you go to a PCB house:-

A) the initial photography, which is a one-off cost, and the price of the boards themselves. For the photography, I guess you are figuring on about ~$300-500 (depending on the number of layers and if you go for silkscreen/solder mask etc) or so. One thing about this, if you change the design, this will have to be redone, so I want to be making as few changes as possible.

B) the number of boards ordered. Quantity is king here, typically it can cost as much to get one made as 5-10.

Remember that I sent you the layout extensively to check your CNC machine, not necessarily as a final layout. Until the PIC code has been written, I won’t know for certain if the circuit in this area is correct. So you may want to hold off going to a PCB straight away and hand build at least one prototype of each board. I will have to build most of the circuitry around the PIC in order to have something to test code in.

Regards
Rob
LIFE….the crappy bit between birth and death

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