I've completed the PCB layout for a MAX7456 video overlay shield board. I thought I would post the initial layout and see what everyone thinks. I'm happy to hear all comments positive or negative. I've not decided what my long term plan for this board is going to be just yet. I'll probably build a handful to see if it works and if there is enough interest I'll produce some boards to sell. I've not got quotes for having the boards built yet, so I'm not sure what the pricing will be.
Short description:
MAX7456 video overlay board in the shield board size to be used with Arduino compatible processor boards.
Two of these boards can be used on one Arduino. (not sure how useful this would be?)
Two layer board
Test points for software/hardware debug
Other features that could be added:
Breakout digital I/O on connector J1. Currently nothing is connected here and there is a little space in the upper right corner of the PCB.
It would be a tight fit, but I thought about adding a video switch to before the MAX7456 and making this into a 4-input video switch with video overlay. The biggest problem is fitting on more video connectors.
More test points, this could be useful if the board was going to be used for a class or some other learning environment.
I'd be interested in buying a PCB if you decide to sell them. If you want to keep your PCB costs to the minimum try seeedstudio Propaganda service. Reading their website they'll share the cost of making the PCB. It'll cost you $30 for 5 boards and seeedstudio will sell the remaining boards from the batch for 7-9$ with minimal shipping cost. Sounds like a good deal
I made a few changes to original design I posted on this topic. I've now purchased a couple of prototype boards. You can see pictures on my flickr photostream here:
I'll be building up the two prototypes over the next week or so, I'm still waiting for a couple parts to come in.
Just curious though, any idea how many IO pins are going to be in use by the shield?
I think something like this, and a small TV, would be great for debugging.
Keep us updated, I want to see how it's going to look on a tv:D
Sample code and/or a library (after it's done of course) to see what interfacing would be like would be splendid! Ease of use would be a big selling point, for me anyways. Newbs looking to expand their hardware selection, but afraid to dive headfirst into pages and pages of code!
Looking great! Definitely going to have alot of interested people!
I never thought of using it as a debug console that's a great idea. I have an old 7" LCD DVD player that won't play DVDs any more but has a video input and will work great with this board.
I'll be sure to keep everyone updated with this thread. I'm also setting up a website, but it's not ready just yet.
Currently the shield uses the following pins:
+5V, GND, Reset*
5 digital I/Os on J3.
J1 and J2 have nothing connected to them.
There is a tiny amount of space available in the upper right corner of the board and I thought of breaking out the digital I/O to a few 0.1" pads. Any interest?
I've seen that some shield boards have stack through connectors, is this something that people want?
SparkFun have a great MAX7456 BoB - you might want to have a look at their setup.
I say its great based on formfactor and appearance... so far I've not actually gotten theirs to work properly (I'm sure it does, SFun are generally pretty good in that regard ).
I'm not real sure if it's even worth it, but the first thing that came to mind when you said that extra space.. for a video shield board, would be a built in IR Receiver.
But that would be easy to add yourself if it was even an interest.
Another thing, I didn't see a place for a reset button, that would be a great area.
One question I do have though, is what's the use for the video in? Does that just add a text-over the video?
Like, what would a connection look like to a TV? Would you need to have a video in(vcr or something) then the video-out to the TV, enabling the text-overs?
Also, if you have the reset button, and don't like the IR receiver idea, could always use RGB Led for a Status LED.
Adr1an: I've seen the SparkFun MAX7456 BoB and it looks nice, I hope you get it working OK, I'd be interested to know what you find.
CaptainObvious: A built in IR receiver might be a nice addition, I'll have to check and see what that would take.
The reset for this board is connected to the reset on the Arduino board, so users can use just one reset for the entire system.
This board does add text over video, but input video is not required for it to run. The MAX7456 IC can generate it's own video, NTSC or PAL. But you are still limited to the character set, plus some custom characters that you can create. Once I get the board up and running I'll post a demo video. The MAX7456 eval kit PDF shows a couple screen shots on page 3: http://datasheets.maxim-ic.com/en/ds/MAX7456EVKIT.pdf
As far as a TV connection, the board outputs NTSC or PAL composite video. Your TV needs to support a composite input, or if the TV only has an antenna/cable input than you can use an RF modulator to converter composite video to channel 3/4.
Something like this: http://www.smarthome.com/7764T/Terk-Mini-RF-Modulator/p.aspx
Or if you have a VCR with a composite video input you can use that.
I got the rest of my parts in today and I've built up the first board. I installed the RCA connectors for the first board. Here is a photo:
I built it up by hand so don't zoom in too close.
I dunno, I still think you may need a reset button. Once I put a shield on my Arduino (Duemilanove) I can't reach the reset button unless I use my pinky, at like a 45 degree angle, lol
But a reset button could be easily added by the user if indeed, it was useful!
But as far as the IR Receiver goes, that's all you would need! It would add a couple dollars onto each board (think they're $3 at Radioshack, of course Ebay is the way to go) I've had quite a few circuits with just connecting the power, ground, and the Output pin directly to my board. (pin 2 or 3 would probably be best choice, for use of the Interrupts available via Software)
It's looking good! The soldering looks pretty good, I haven't had a chance to try any SMD parts (it's mostly fear! and no real use for em yet) but I'm jealous!
CaptainObvious: Good point about the reset button being under the shield, maybe I'll put some SMT pads down for reset button. Then I (or a user) could install a reset button.
The board powered up and the basic functions seem to be working. I have a bunch of testing I'm going to work on next.
Here is today's photo update:
one easy solution is to find out if there is no tracks right on the top of the original reset button... and drill a hole on the shield... so you can reach the reset button with a toothpick...
Project status as of 9/23/2009:
The prototype is working well, I've finished most of the testing. I'm making a couple minor changes to the board to make it easier to manufacture. Next I need to find a contract manufacture to build up a batch of boards.
I may sell a few board directly but long term I'd like to find companies to distribute the board. Does anyone have experience with selling boards through Maker Shed? http://www.makershed.com/
I presume you are looking for a company to put all of the components on the board then, not just make the board.
Seeedstudio do a service of that nature, so do ourpcb. I have not had assembling done at either but the board quality from both is great. You will have to contact them for a quote.
Project status 02/18/10:
Well I'm sorry to say that this project got put on the back burner and was not worked on for a while. But now it's back and moving forward!
I've updated the PCB with some small changes that were suggested by people here on the forum and others that emailed me. Thanks for your suggestions.
Changes to v.10.02:
Added reset push button S1
Added power LED D1
Added digital I/O breakout at J7 and 5V/GND at J8
Switched to dated based revision, now v.10.02
Switched standoffs to pass-through connectors
I'll be building up a couple of the boards this week to see how things are working.
Here is the PCB layout and a couple photos of the board that I just got back:
).
