[psas-avionics] min trace width
Hi all, I'm working on the the APS board and I was just wondering what the min. trace width should be. One of the ICs I'm using is a 3mm x 3mm MSOP-10 (TPS2490 hotswap controller) and the lands are narrow and close together meaning if I use the default 0.016'' trace width, I get a keepout error. Are 0.01'' traces wide enough? Thanks! Scott ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
[psas-avionics] git
Hi again all, It seems to be becoming more and more apparent that I know nothing about this git (and linux in general) thing... I seem to have lost the ability to use the psas eagle library and don't really know how to get it back. I know at the last capstone meeting I was having some problems getting connected properly (again, not all that sure why) but I seem to be connected now. How do I actually access the library in eagle? Thanks for any help! On that note when it comes to the diff thing, I'm sure I'll have tons more dumb questions, so please bear with me! =) Scott ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
[psas-avionics] more EAGLE questions
hi again all, does anyone happen to know if a polygon can be somehow converted to smd, or vice versa? The reason I ask is because one of the parts I'm creating has a ground pad which has a circular notch in one of the corners to indicate pin one. If there is not a way to represent this, can I just use the usual rectangular smd shape, and use some other means to mark pin one? In other words, is it that important to represent the notch, or can I just leave it out? Thanks! Scott ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
[psas-avionics] eagle parts
Hi all, This may be a goofy question, but I'm unclear on the matter so I'll ask it anyway... I've noticed that many of the existing parts in the psas EAGLE library have pins represented in both the top layer and tplace layer. I'm guessing that the tplace layer pin represents the physical pin and the top layer representation is the footprint. Is this correct, and should we be doing this as we create new ICs in EAGLE? thus far I've only used the smd function for pins, but it wouldn't be too hard to add rectangles using the tplace layer. On the same note, I also notice that the dimensions of the pins in the top layer seem different than those drawn with the tPlace layer. Is this difference in dimension represented somehow in the datasheet? Thanks for the help! Scott ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
[psas-avionics] meeting
Hi all, This message is for the capstone group. I am working on a final project that's due today and so I don't think I'll be able to make today's meeting. I thought I'd be finished by now, but it's turning out to be a bit more involved than I expected. Sorry guys. I'll be checking blogs to find our what went on in the meeting, and I will try to get what I have for schematics up on the wiki ASAP. Talk to you all soon! Scott ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
[psas-avionics] power switch controllers
Hi all, I'm researching candidates to replace the current power switch controllers on the APS and I've got a couple questions. First: Is there such a thing as too small? I'm looking at a 3mm x 3mm 10-pin SOIC package. I think the current chip is like a 6mm x 10mm 8 pin package. Does a smaller chip with more pins just complicate things? Second: I'm currently basing my search on the ability of the IC to meet the given specs (i.e. adjustable current trip/trip delay, latch-off , soft-on/soft-off, etc.) and am using the specs of the old chip as sort of a guide for all other specs. My understanding is that a wide range for Vsupply is also a must (9-20V is what I've been told). Are there any other features/specifications which need immediate consideration such as overvoltage/undervoltage lockout, quiescent current, etc? Basically, there are a lot of these chips out there, and the datasheets for these chips provide so much data, so I'm just wondering if there are a few benchmark specs that would tell me whether the part even deserves consideration. Thanks!! Scott ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
Re: [psas-avionics] charger
Hey guys, It's a nice coincidence that you're talking about the umbilical, because I have been trying to start some research on this topic. After reading your discussion below, I think I'm a little unsure as to what I'm doing with this part of the design. Per the discussion below, the connector is already chosen, so is integrating that connector into the APS what I should be focusing on? Also, is there documentation on the wiki about the umbilical? I feel like I've poured over the APS design documentation, but can't really find too much about this. Any help/suggestions would be greatly appreciated! Thanks! Scott On Mon, Feb 2, 2009 at 10:53 PM, Andrew Greenberg and...@psas.pdx.eduwrote: Hi David, The shore power connector on the rocket connects has three purposes: 1. It conveys power (shore power) to the rocket to charge the batteries and run the avionics system during testing or before launch. Shore power either comes from a power brick plugged into the wall, or it comes from a 12V to 20V DC-DC converter that runs off of the launch tower computer's solar-recharged lead-acid battery pack. You can see the solar panel, batteries, and launch tower computer here: http://psas.pdx.edu/Lv2LaunchTowerElectronics/ag_lt_ltc.jpg 2. It allows us to talk directly to the APS microcontroller using a three wire UART (TX, RX, GND). 3. It acts as one of many launch detect sensors: when we're armed for flight, and the launch tower computer fires the igniter, then the shore power connector being yanked out pretty much means you've launched. Of course it's never that simple, because the cord could fall off by accident, or the connector could get jammed, etc. We have a fancy lever mechanism for pulling the plug out of the socket on launch; when we break out the launch tower computer this spring for testing, we'll show that off. The connector we're thinking about using is a high reliability medical connector that has just the right properties: it's keyed, it slides out easily, it doesn't jam, and it has high current capabilities. I don't have the part number right now, but eventually we'll post it to the web. Right now we're thinking of a seven pin connector: 2x V+ 2x GND 1x TX 1x RX 1x Launch detect (shorted to ground) We'll have a short on the bench cable for testing, and we'll have a very long (~ 20 ft) cable that goes from the LTC to the rocket for the actual launch. Andrew da...@cecs.pdx.edu wrote: hey, doing some research on the charger, and am curious as to what type of external connection we will have, are we simply plugging into an outlet, or are we dealing with a cable of some sort? David -- --- Andrew Greenberg Portland State Aerospace Society (http://psas.pdx.edu/) and...@psas.pdx.edu P: 503.788.1343 C: 503.708.7711 --- ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics ___ psas-avionics mailing list psas-avionics@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-avionics
