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geogecko

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Everything posted by geogecko

  1. Finally got some information back on the Motorola FS-Oncore from a distributor. Here is the e-mail. They also sent some design guides and information about antennas. Not a bad price for a small GPS. Ouch, that eval kit is expensive though... Hello Jason, Thank you for your interest in our products. I've attached our antenna price list. The following is the latest information for the FS Oncore: 1. We are currently taking orders for the FS Oncore module, based on the MG4100 GPS chip, eval kit. The lead time for the kit is stock to 8 weeks. 2. The part number is 10001700 a
  2. Thanks for that information. It appears that there was an earlier part, AT45D041A that was a 5V part, but it looks like it might be going obsolete. Actually, I just got done looking at the data sheet on the GPS, and it runs off of 3V as well, so that would be a good fit. The PIC can run off of that voltage as well, so I think that works. I only wish the 4MB part was available in DIP packages. I guess I could just get an SOIC-8 package, and solder little wire wrap wires onto each lead, and then solder it to a DIP-8 socket. That would probably work for development. So, now, I guess th
  3. Well, just when I thought I found the solution to the 200KB GPS operating system requirement (a serial EEPROM from Microchip), I am now back to square one. Microchip specifies their serial EEPROMs in k-bits, not k-bytes, as I assumed they were. So, I found a nice 512KB serial EEPROM that I thought would work, however, its really only 64KBytes. Does anyone know of any 256 or 512 KByte serial EEPROMS either on SPI or I^2C bus? I would prefer to have them in an 8 to 14 pin DIP (.300) package (for prototype purposes), as well as a smaller SMD package.
  4. Well, from the likes of this picture, the Garmin eTrex uses the exact same patch antenna in their GPS units. http://groups.msn.com/rccam/rccamprojectph...oto&PhotoID=126 It looks like their ground plane is no larger than about 35x35mm, so maybe I can get away with that. Regards. Jason.
  5. Thank you all for your replies. I will be able to provide possibly a 25x40mm ground plane, but that's probably it. That being said, how do you go about making the ground plane, and how do you apply the antenna. Is the antenna just stuck to the GP with the included double sided tape? Also, isn't the connector (or pin) coming out of the back side of the antenna (e.g., the side with the tape on it)? So your PCB would have a ground plane, with an isolated plated through hole where the pin would come through, and then that would be soldered on the opposite side of the PCB? I'm just trying
  6. I will check out gpsflight.com tomorrow. Thanks for all the useful information. Actually, I was looking for a passive antenna. The FS Oncore made by Motorola already has an LNA built into it, so you could use a passive antenna if needed. 25mm square, that's about 1 inch. That may be small enough, but the 18mm one sounds nicer, too bad it's non-stock. Anyone know the requirements of mounting an antenna like those? The data sheets talk about a rather large ground plane. I was thinking either same size as the antenna ground plane, or none at all. I think I'll take a look at gpscity
  7. I'm interested in using the FS Oncore GPS modlue from Motorola, and am needing a very small (preferably no bigger than 0.5"x1.0", smaller is better) GPS patch antenna. Does anyone know where to get one? Regards, Jason.
  8. Hmm...guess it requires you to have 200k bytes of ROM in order to store the GPS operating system. That stinks. So much for using just a PIC for an interface, now you need a rather large (256KB) EEPROM or something.
  9. I had a Motorola seminar at work recently, and they skimmed over a new product called the FS Oncore. It's a GPS receiver that measures only 12x16.6mm (i.e., smaller than a US dime). Here is a link: http://www.motorola.com/ies/GPS/ You may have to register to get to the link, as I think I did. Looks like something that might go into a cell phone. I'm considering another project, and have been looking at small receivers. This is the smallest one that I have found to date. I think they even sell patch antennas to go with them. Jason.
  10. Although I haven't been a part of this discussion, I've been following it for a little while now... I'd have to say go SMT. It makes for a much smaller board, and reduces component height. The only thing I might consider is to have a DIP-to-SMT socket for any microcontrollers that would be used, that way, people with "hobby" programmers aren't left to find a way to program the devices. This also lends the ability to develop firmware while using the actual board. Just my thoughts...
  11. Well, I had some time to work on the project some this weekend, and I finally got my camera back from the shop. Thank you for the tips in building it. Now if I can just finish the software part! Jason.
  12. I now have the EEPROM part of the program working properly. Thanks for the tips there. Now. Here is where I've run into an issue with how to do something. I currently have code now that checks for the trip point of the landing lights, a too short pulse, and a too long pulse. I need to add some points (a center stick check point, and full up stick check point, and a full down check point) for the setup routine, however, I am unsure how to go about this. If you look at the code, once it finds a match, I exit out of the checking part of the routine, and do whatever needs to be done. I gu
  13. Thank you for your replies. I cut out my perf board outline last night, now I just need to epoxy some of the components to the board, and solder it all up. I bought some of that 30 AWG wire you are talking about, so that should work well for building the circuit and for the LED wires.
  14. So then do you make a power and ground bus by using a wire or something, or just point to point your power and ground? Also, have you found a good way to attach LEDs to foam models? Pictures would also be nice. Thank you, Jason.
  15. Next issue: I'm working on the EEPROM code that will allow a similar type setup used in the Landtastic project. Question is, I have a value, the rate at which the strobe flashes (or cycle time, rather), which is currently set as a constant in my code, then stored in a RAM variable when needed. I want to change this to pull the value out of EEPROM memory, but had a few questions on doing so. 1. Should I just read the value in EEPROM memory once when the PIC initializes, and store that value in RAM, or 2. Should I not even use a RAM variable, and always read the value from EEPROM wh
  16. Kilrah. Hey, thanks for the information about the 16F676. I didn't know it existed until now. As far as the debounce thing goes, I too used to use a delay loop, however, a good debounce is about 3ms long or so, if I remember correctly, and I'm not sure I want to wait that long in a delay routine. Actually, I guess it wouldn't be that bad, I'm not timing anything that is real critical right now (besides what is taken care of with an interrupt). I'll start with that, since it's the easiest thing to do, and if that doesn't work out for me, I'll go another route. I've just spent the la
  17. Thanks for the information. I would buy the plated through hole prototype boards to use, but they are considerably more expensive. I think I picked up a 12x4 inch perf board for $10. I'll take your advice on the adhesive for each component, as I'm making one for a friend, and he will use his in a glow plane. I like those FETs you are using now, the 2N7000's, have you found any that you like to use that have a rating of 500mA? I think I found some called BS170's, but I think they are being phased out. I just ordered the ones you are using in the landing gear project because it saves y
  18. I'm making a similar project to yours (Nav-Lights) and wondered how you attach some of the components, like the FETs or transistors. Do you glue them to the perf board first, or just put them through the holes and solder your wires up to them. I know this is a trivial question, but I'm getting ready to make the board, and wondered the best way you found to do that. Also, how about your right angle header pins? Thank you. Jason.
  19. Another option is to use a step-up DC-DC controller. I think one from Maxim is also available, maybe the MAX773 would be a good fit. Provides up to 1A of current, and can provide 5, 12 or 15V output. It requires an external N-channel MOSFET to provide the current. I haven't ever used them before, so I'm not sure of the characteristics. Do they require more current than would normally be required to generate a voltage that is higher than the input? I don't know, but I assume so. So, I guess it really depends on how long of a flight time you want to get out of your packs. If you need e
  20. Kilrah. I see about why you include it in the code now. I'm going to leave mine in for the time being, just need to remember to change it. Jason. Okay, so, what is a good number of pulses to average when checking pulses? I would prefer to use a 2^N number of pulses to average (as it makes the dividing easier), i.e., 2, 4, 8, 16, etc. I was thinking 4 would be good enough. This project is coming along pretty well. I got the magnetic buzzer in the mail a few days ago, and it seems like it will be loud enough. I also have my EEPROM write/read routines written, now I just need to
  21. I am using a PICSTART Plus programmer to program the chip directly. So every time I do an "Erase Device" I'm losing the OSCCAL value? It sounds like I should leave it in for now. Hmm... You would think that Microchip would have write protected it. We shouldn't be changing it from the factory setting in the first place. Do some people change the value on purpose? It is new for me, because on the 16C73A, there was no such thing, when I was in school. Of course, neither was there FLASH devices. Thanks for all your explainations. Hopefully someday, I can call myself a professional PI
  22. I've seen a lot of people out there with this retlw in their code, which is why I added it to mine. From what I can gather from the data sheet, (and what you have said) the instruction/value already exists in memory when you get it from the factory. The only reason I can think of is to why people are including this instruction in their code (as I have) is "just in case" their program filled up the entire amount of memory in the PIC, including 0x3FF. If you had this instruction at the end of your code, even if you had an instruction in your program that went into 0x3FF, the org 0x3FF and
  23. I now see. So, would a "Stage Hand" also be considered a Grip? That's cool. I should have put 2 and 2 together (maybe for me, I should have put 1 and 1 together). I was a little worried about moving the code to the main routine, but knew it had to be done, since it wasn't really part of the interrupt servicing. I'm glad it worked out so nicely. Just a couple more added instructions checking flags, and that was all that was needed. So, basically, if I leave the code in that programs the OSCCAL value, then I will always get that message? I have noticed that on accident I programmed t
  24. Okay, I was starting to think that it was 5V. I wonder why they spec servos with 6V (I guess if you have a glow plane, and use a 5 cell pack?). Interesting. I went to see The Passion of the Christ last night with my wife, and as I was watching the trivia questions before the movie, there it was. What is a Gaffer? "It said a person in charge of the lighting for a scene." Guess it depends on where you are coming from. What that has to do with R/C, I do not know, but okay. Have you noticed how many posts this thread has gotten? Interesting, huh? I finally removed all the pulse che
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