Serial To Jaguar PCB

linuxboy · April 7, 2012, 11:37pm

Hi All,
Attached is a screenshot of a project I’m working on in Altium (by the way, does anyone else use that, particularly because of the FRC license?).

This PCB is meant to convert the DB9 plug on the cRIO to a 6P6C RJ11/12 port, with termination across so that the CAN bus works.

I personally do not enjoy making those plastic converters, and would rather a PCB, I have an old revision made in EAGLE on the robot (and it worked), and I can post a picture of that later.

Let me know what you think,
Oliver

RyanN · April 8, 2012, 7:41pm

Good idea, but not a good design in my opinion.

You would have a heck of a time getting the screw that holds the serial port to the cRIO screwed in.

Rotate the RJ-12 port to be in straight in line with the RS-232 port.

My $0.02.

Alan_Anderson · April 9, 2012, 1:13am

I’m confused. What need is this supposed to fill? If it’s just something to plug into the cRIO’s serial port and provide a way to connect a Jaguar, a perfectly useful connector was included in the Kit of Parts.

EricVanWyk · April 9, 2012, 1:30am

This looks like a great introduction to PCB design!

I agree with Ryan, re-arranging the connectors might make life easier. You should be able to export the 3D model of the circuit board to something Solidworks or Inventor understands - try modeling the screws and the tool paths in one of those and re-work the design from a ergonomics/usability angle.

linuxboy · April 9, 2012, 7:22pm

Hi,
Sorry for the long response time.

Eric & Ryan, I will rearrange that! the reason I minimized it was for price. The one we used on the robot this year did have room for screws, I just didn’t have any screws and it worked fine, didn’t pop out at any point, although, when designing a product I would want it to work with screws.

Alan:
I have had issues with those plastic things (although that may have just been due to the supplier), either way, I trust using a PCB a bit more than wires, while, when made correctly, I think the plastic connectors work fine, soldering a resistor to wires inside a plastic case, just seems like bad practice to me, and I think this may be more reliable.

linuxboy · April 10, 2012, 4:14pm

Attached is a modified board, same footprint, what do you guys think?

duane · April 11, 2012, 1:07am

I’ll order a half dozen.

linuxboy · April 11, 2012, 2:19am

Awesome :).

If anyone is interested in a prototype, PM me so we can discuss details, since I haven’t settled on a final design, and I’ll want to talk to each person getting a prototype. I will (hopefully) have a couple boards of some revision with me at champs.

Oliver

dyanoshak · April 11, 2012, 2:10pm

This looks really great!

You’ll be in full production by the end of the week right?

EricVanWyk · April 11, 2012, 2:47pm

I’d be interested in one. You might also want to talk to our Altium sponsors, give them the warm fuzzy feeling of knowing their donation was helpful.

For whatever reason, DB connectors are always a purchasing nightmare, especially with high pincounts (25,37). For something that purports to be a standard, there sure are a lot of variations. If you intend to support this design long term, assume that the specific part number you order today won’t be available tomorrow. With that in mind, leave a little extra room to fit the replacement part. It looks like your design has plenty, but keep it in mind if you make a housing.

linuxboy · April 11, 2012, 4:38pm

Wellll, the Altium license is non-commercial so I don’t know if I can produce and sell the devices, does anyone know?

Eric, will you be at champs? If not, I can probably mail you one, or I can just send you the gerbers or the altium project if that is easier for you. I do intend to eventually have this be something many teams can use year to year, once I figure out licensing and a supplier. (Anybody interested?) In terms of letting Altium know I’m making use of the donation, would I do that at champs, or should I email someone?

Oliver

techhelpbb · April 11, 2012, 8:42pm

How many, how fast, how much cost to make, how many to stock (who’s paying for that), what’s your profit, and how is it being sold? Anything fancy I can’t see from the images provided (crazy silk screens, glass epoxy boards things like that)?

I can answer some of all of those questions if you can’t. If you’re worried about the licensing I can help you with that as well.

If you prefer you can also try this:
http://batchpcb.com/index.php/Products
http://www.sparkfun.com/tutorials/315

linuxboy · April 12, 2012, 12:25am

Well, I’m not really looking to make much off this, but if I make anything off it that would go to my team. At a QTY of 500 I think they are $4.12 a piece, components and board (from the place I got a quote). The silk screen is pretty basic, I’m going to be re-adding the FIRST logo to the more recent one (just have to re-size it). I don’t know what a glass epoxy board is haha. I’m hoping to talk to some people at champs and see if they are interested in backing it (with their logo added to the silk of course).
In terms of licensing all I know is it says non-commercial.
I order PCBs from http://dorkbotpdx.org/wiki/pcb_order when I’m prototyping.

Oliver

Tristan_Lall · April 12, 2012, 12:47am

I wouldn’t bother with the FIRST logo. FIRST is picky about how their (trademarked) brand is represented, so you shouldn’t imply endorsement.

Incidentally, remember to check clearance versus both versions of the cRIO (cRIO-FRC and cRIO-FRCII). The RS-232 port positions are different.

Also, you might consider an RJ12 jack like the one on the Jaguar, where the connector is inserted perpendicularly to the PCB, if you want to avoid the cable pointing straight up (relative to the cRIO).

And definitely indicate the resistance of the terminator, either in the silkscreen or the copper.

DonRotolo · April 16, 2012, 8:14pm

Some design tricks to reduce costs:

Use a solder cup DE9 and a 2-sided board. Put “board edge” pads there, 4 on one side and 5 on the other. The 1/16" PC Board material will fit between the two rows of solder cups, and you solder straight to them. These DE9 connectors are dirt cheap, much less than the right angle solder pin style.
Similarly, use this connector, again edge mounted to a 2 sided board.
Make the boards yourself. You don’t need plated-through holes. PM me if you need to learn how to fabricate several hundred of these cheaply.

For those thinking of stress on the connectors, particularly the RJ-45, use a potting compound to reinforce the connectors.

For 100 boards:
DE-9F: 0.60 ea
RJ-45: 0.589 ea
PCB material: 1" x 1.5", 24 per 6x6 board, 0.5525/ea
Resistor: call it 0.10
Misc: 0.50 (etchant, developer, solder, potting compound, etc.)
Total: $1.80 each for 100

And you can probably cut that a little more by careful selection of suppliers.

EDIT: If that’s not an RJ-45, similar ones in RJ-12 or RJ-14 (whatever it takes) can be had for a little less.

linuxboy · April 16, 2012, 8:30pm

Awesome tips Don!! I’ll work on a variation like that, I imagine it will reduce the board size as well (which in turn reduces cost). Ooh boy, I think this means designing my own foot print, that should be… educational :D.

Thanks again,
Oliver

EricVanWyk · April 17, 2012, 12:30am

Tip: Its really easy to go back and forth between excel and Altium. This is really helpful when making weird footprints. Otherwise, just set your snap grid to whatever weird value you need for the moment.

techhelpbb · April 17, 2012, 5:23am

I have 2 LPKF ProtoMat 92S:
http://www.surpluseq.com/lpkf-protomat-92s-pcb-circuit-board-plotter/

(Don’t be fooled by the price at the link the software for the machine is proprietary and a few thousand dollars…these were usually $11,000-$12,000 new…without the accessories I have)

My units are complete with the solder paste deposition units.

I’ve been working with LinuxBoy in private to fund his effort. I thought that we wanted to do this by sending it out, but if we want to get handy with this:

I can directly import his Gerbers into the software and palletize them. Then isolate traces into the copper with the mill.

If he sticks to double sided and no through hole plating this way no chemicals are required. I can run both machines at the same time. The work decks are 15" x 22" with a 22" long section dead center that I have to have unpopulated 1/2" wide down the length of the machine (PCB hold down).

The traces would be isolated in plane of copper which could double as a ground plane.

I can handle traces down to 1 mil (0.001") according to machine specifications but i can get closer if I mess around. So we can effectively engrave text into the PCBs. I’ve even done whole images.

I can tin plate the boards with LiquidTin and I have access to green coat (or whatever color you like).
http://www.mgchemicals.com/products/421.html

I just don’t silk screen here.

This being said, I encourage everyone to tinker with the chemical/photochemical production of PCBs but I’ve got the yellow hand prints from ferric chloride on my shop walls to prove that it’s not the thing to do when you’re tired. I’ve actually built a fume hood, photographic exposure unit and ammonium persulfate etching bath but it’s not something you want to mess with if you don’t want to give up a corner of a room.

I can plate through holes but I dislike doing it because of the sulfiric acid involved. Usually if I really need that I can either use the solder paste deposition unit to put paste in the PCB holes after drilling or I have a copper grommet kit.

I have a modified toaster oven I use as an SMT oven (better thermostatic controls and timer). I have a large ultrasonic cleaner and if not that dishwashers work great!

In relation to not just this but for anyone else interested in using these let me know (I own them personally and I have all the tooling on hand). I also have my own pick/place hardware but the only problem I have right now is it’s occupied with other work.

system · January 5, 2020, 5:58am