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Posts posted by NJC

  1. Hi everyone. I was looking through the Energia library (cores/msp430/twi.c) today trying to debug an issue I have been seeing, and noticed the following code:

    /* Work around for:
     * If the master does a read and then a write the START interrupt occurs
     * but the RX interrupt never fires. Clearing bit 4 and 5 of UCBxCTLW0 solves this.
     * bit 4 and 5 are however marked as reserved in the datasheet.
    UCBxCTLW0 &= ~0x18;

    Does anyone happen to know why this is? I have searched high and low for a reference on TI's forums and in their documentation to no avail.


    Thanks for the help!



  2. @@bluehash Thanks! I wish I had more time to be active in the community. I am still using the MSP430 for almost all of my projects, especially the FRAM series. I've been a bit too busy with school to write about what I've been working on.


    Thanks for editing the post! Good call.

  3. Hi Everyone!


    Recently, I released a Bluetooth Low Energy BoosterPack based on the BLE112 module from Bluegiga. The full-featured BoosterPack is a bit expensive, but there are a few different options that can make the BoosterPack very reasonable. I wanted to create this post so that you guys can ask me any questions you may have about it.



    Blank PCB: $10 - The BLE BoosterPack was designed with 0805 components and other easy to solder parts making it easy to hand assemble. For $10, you get a blank BoosterPack that can you assemble yourself. The layout and bill of materials (BOM) is available on GitHub. If you need help with finding a component on Mouser or Digikey, let me know.


    BLE Only: $40 - This options contains all you need to use the BLE112 module with a LaunchPad. Additionally, the USB connector is included, allowing stand-alone use with your PC and USB firmware updates. This means that you don't need the CC Debugger to update the BLE112 firmware.


    Complete with Linear Regulator: $50 - Rather than using a switching regular, this option uses a linear regulator to reduce cost. Other than using a different regulator, this is the full-featured BoosterPack.


    Complete with Switching Regulator: $65 - If you care about maximizing your battery life, this is the board for you. Using the TI recommended switching regulator, this board can has unbeatable power consumption.


    Check out the demo video for a bit more info.



    While the full-featured board is a bit pricey, it does include all you need to make your project completely wireless: A BLE module, a lithium battery charging circuit, and low-power voltage regulator.


    If you have any questions, please don't hesitate to comment here.


    Thanks guys!


  4. Too many times have I wished that there was a UART based bootloader for the MSP430. Sure there are USB bootloaders for the larger chips and wireless bootloaders for the CC430 chips, but what about the Value Line series?


    I was wondering if anyone has researched this or attempted writing the code, regardless of whether or not it worked. If not, I'm going to start doing some research and try to pull together a blog post on what it would take to create a bootloader, and then build one (hopefully with help from anyone who's interested).


    EDIT: Apparently most TI chips have a BSL (bootstrap loader). I should have probably known that. O well. Thanks oPossum.

  5. One great application which an MSP430 would benefit from an RTOS is in a wireless mesh network. Many tasks will need to be done on a single chip randomly, sometimes causing conflicts. If I understand it correctly, an RTOS is really just a way to manage tasks in real time.


    Hope that helps put some perspective on it!

  6. For a bit more expensive option, I just recently purchased one of these on a whim.


    http://cgi.ebay.com/2in1-SMD-Hot-Air-Re ... 3848wt_968


    I'm not sure I really got the best bang for my buck, but I needed it quickly and decided to impulse buy it. Turns out,it works really well and I am very impressed with it. I can't speak to the durability and longevity of it since I have had it for only 2 months now. But I really love the extra tips and nozzles and love only having one solder tool on my work bench.

  7. OCY,


    The IPTR package should fit just fine. Currently the second wave of prototypes are being manufactured, so I should get the boards and be able to test them in 2 or 3 weeks. There should be a few extra unpopulated boards left over from this upcoming batch. If you would like I could email you when the boards come in?



  8. The RST and TEST are the two signals you need to do programming or debugging. And you always need Vcc and Vss no matter what you do.


    You actually don't need Vcc if the chips is powered externally. More accurately, you do not want to use the Vcc of the LaunchPad if you are powering the chip externally. Two power supplies fighting ends terribly. You need the ground though in order to provide a reference for the 2 programming signals.


    Example: For an MSP430 hooked up on a breadboard with RST tied to VCC via a resistor (47k), and powered by 2xAA batteries, you only need to connect the GND, the RST, and TEST pins in order to program the chip.

  9. Doc,


    Take this with a grain of salt, since I never have used one of the pocket scopes. Personally I wouldn't buy one. $200 is a lot of money for something like that. You can definitely find a used scope on eBay for that much or even less, and the old analog scope will be much more useful. Theres nothing like having a real scope in front of you to use. I mentioned that you should check out the Rigol scope in your other post doc (on the workstation thread), you can also get it for $350 if you want to haggle some sellers on eBay. For a bit more cost, you get a scope you will use the rest of your life (unless you have enough money to upgrade to a few thousand dollar scope). Apparently the Rigol scope has a software hack too, that allows you to increase the bandwidth (haven't tried though).


    I would recommend a USB/pocket logic analyzer, but not a scope. BUT, that being said, if you can't spend the extra money, and like the little scope, a pocket scope is better than no scope at all. :-)

  10. Doc,


    I bought an oscilloscope about 2 months ago and its been the best money I've ever spent. It's SO useful its amazing. I'm sure lots of people have heard about the one I got, but I thought I'd mention it again. The Rigol DS1052E - $400. I haven't tested the spectrogram feature yet (who knows how well that works), but everything I've done on the scope worked perfect. The front panel is responsive and overall, I am very impressed. I like it much more than the stupid low end Tektronix scopes in the labs at school. I was gonna do a review on my blog of the scope, but figured thats not the best content for my blog. It's a great scope though.


    http://www.amazon.com/gp/product/B003MY ... B003MYND5A


    Edit: I also forgot to mention that I got a cheap old analog HP signal generator on eBay. Is useful, but wasn't worth the $40 I spent on it. I have a bunch of problems with it. Digital signal generators are the way to go.

  11. Hey Everyone,


    Just thought I'd put my 2 cents in. I love the 55xx series, and have used 2 of them so far (the 5528, 5524, and soon to be 5510). The on board USB is a pain to get working to say the least, and I have only managed to get about 450 kbps for speed, which is a bit frustrating. I have been using the UART with an FTDI chip since I can easily exceed 1M baud with it.


    As far as doing other things with the chips (non-usb) its just as straight forward as the other MSP430 chips. There are code examples on TI's website which show how to use the peripherals (my favorite is the hardware multiplier). For a basic circuit check out the target boards TI has for sale, they have the schematics posted online.


    Also, for a development board for the 55xx devices, TI does sell a board with a nice socket for the 55xx boards (they sell a bunch for different package sizes too). They are a bit expensive though. I am currently working on making a small development board for the 5510 which I would sell. The board is basically ready but I cannot find someone who has the right package in stock (since I cannot sell boards with samples on them). The boards came out real nice though! Lots of cool features. Lol.


    One last thing, you can definitely program the 55xx chips with the LaunchPad, I had been doing it for months and it works great.

  12. mitsu-lover, welcome to the world of embedded systems. there isnt much you CANT do with a microcomputer if you have enough time to build and design it.


    I have a blog which might be able to help you get started with the MSP430 if you have a LaunchPad, and can definitely still help you get started with any MSP430 development board. If you don't have any hardware yet, I would recommend buying a LaunchPad (but find a place that has it in stock first).


    http://www.msp430launchpad.com/2010/07/ ... arted.html - I would recommend starting here since its the first post I have where you actually start playing with the LaunchPad. I think the best way to learn is to just get your hands dirty and play around.


    http://www.msp430launchpad.com/2010/07/ ... ation.html - this is another possible place to start, it discusses the circuitry in the LaunchPad a bit too.


    There are a few other good resources available for the MSP430 and LaunchPad. This forum is also one of the best places to start. I would just start playing around before you try to understand what the code is actually doing line by line. It will be much easier to learn what C is, after seeing it magically work.


    Most importantly, have fun!

  13. My bad Doc. I saw "Nokia data cable" and instantly brain-auto-piloted to Nokia LCDs. I need to find some of my own Nokia chargers, the LaunchPad cables drive me nuts.

  14. Well here are a few pointers. Its much easier to use an opto-isolator with a digital signal than an analog one, the only thing to look out for with using a digital stream over an opto-isolator is how fast the isolator can switch at. I use 2 AAA batteries and use the built in isolation from the MSP430F5528 chip for USB (no idea if this is really safe enough for me to let anyone else use it though). An easy way around that is to also just use 2 MSP430s connected via IR, the one thats hooked up to the analog stuff is battery powered. A good rule of thumb, have no possible connection between yourself and ground.


    PLEASE NOTE: This is just the ramblings of a crazy engineering student. Only put electrodes on your body at your own risk. Do NOT to hook ANY electronics up to your body or anyone else's. So please, do not take my crazy assumptions and thoughts as facts, no matter how factual they may sound. (Be careful please, :-P).


    Books I have and like for Biomedical related electronics stuff. The books are expensive new, but I found great prices of them used ($30 each).


    Design and Development of Medical Electronic Instrumentation



    Medical Instrumentation Application and Design


  15. I'm studying bioengineering and i really like those projects that involve biomedical data acquisition and processing. I want be able to implement it but it would be intersting to see how it is done.


    I'm REAL glad you mentioned this! Here's why: I just did a search to see if I could find a link for you to the IEEE document that explains the algorithm I am using for beat detection. I have an IEEE subscription so I can get the article, but I'm not allowed to just share it with everyone sadly. Anyway, my search led me to the actual document I use on a random universities website (not sure how they get away with posting it though, I won't ask, lol). Though heres the interesting part, the university provides an errata sheet at the end of the article which corrects a few errors which I did not know about!


    Enough of my rambling, here is the link to the site: http://www.engr.wisc.edu/bme/faculty/tompkins_willis/Pan.pdf


    If you also have questions about the analog side of Biomedical Instrumentation let me know, I could also recommend a few textbooks which are great resources. Though the circuit for an EKG is VERY simple.

  16. Hey everyone....



    bluehash: Yes, that is how this works. When the LaunchPad is streaming data you can stop the stream by clicking the stop button on the GUI, then you can send any command. Your question made me realize that I should have greyed out the other buttons in the GUI while the device is streaming. Oh well, maybe in another release.


    heres the answer to your question from my blog comments. I hope I answered your question, if not, let me know. About your first comment, Berstein's library is amazing for sure! I can't believe it took me so long to find it, very easy to use and customize.



    DC means no change in voltage (0Hz), you can have AC with a voltage offset. So it is possible to measure an AC signal if you are careful to make sure the voltage ranges stay within the 0V to 3V (or VCC) range. I actually use this for reading something similar to an EKG; the analog input comes from an op-amp amplification and filtering stage. The trick is to make a reference voltage (or a "virtual ground" as I like to call it) at about VCC/2. For example, running on 3V with the MSP430, provide your analog circuitry with 1.5V as a "virtual ground", so to your analog device 3V seems like +1.5V, and GND seems like -1.5V. I know it sounds complicated, if I'm not making sense I can draw something up quick for you. It's a nice trick which has helped me immensely.


    @doc and rob

    hmmm, logic analyzer, I can put some thought into it. the problem is that the msp430 code would be super simple and that would turn into more of a software (computer appplication) project. i'll think about it though, i might be able to do something tricky with it. plus i could then explain how to make and use buffers in the chip... hmmm....


    and doc, keep us posted with the nokia LCD! very interesting, I would love to see how that comes out. I've been thinking of getting an LCD to play with myself, but I think I want a bluetooth device first.

  17. If theres interest, I might be able to post some code with a circuit to do this. I'm currently working on a small side project where I do some DSP to recognize the heart beat in an EKG (called QRS detection for those who are curious).


    It's a cool idea for sure! Maybe it would even be possible to make the necklace smaller and more like a piece of jewelry. Could use a small battery on the back of the neck, and use the metal chain to conduct electricity to a pearly light type thing... too bad I didn't see this earlier, would have made a nice silly Christmas present.

  18. I finally got around to posting my final post in the scope series. I just wanted to thank Doc for his help a while ago with testing the code. If anyone finds any errors, or typos, or anything else please let me know; its hard to make sure everything is perfect.


    http://www.msp430launchpad.com/2010/12/ ... scope.html


    Any ideas on the next post? I'm open to suggestions. For now I'm thinking I2C communication between multiple chips, but I would not mind a distraction from my all my plans.

  19. Very interesting project. I have skimmed through the posts relating to this project, taken a look at the code and have one question. Do the MSP430s communicate with each other? I might have missed one of the posts which discussed this, so I apologize if this has been explained once already. If so, do you use I2C? or some other method?

  20. You should have no trouble adapting the code, NJC's really good at commenting.


    Thanks Doc! I still have trouble getting the motivation to comment things. But it is amazing how important comments can be.


    sloso, a big difference between a software UART and hardware UART, it is important to keep this in mind. Also, I have a few articles which are on UART, one day I might make an index sort of thing, for now you can just search my site for UART and find any related posts. The links above that NatureTM and Doc mentioned should be a great place to start.

  21. Yeah, the setup is definitely the hardest part. I'm excited to see how well GRACE works, I only found out about it from here yesterday.


    Also, I forgot to mention one thing. Another HUGE difference between the two ADCs is that the SD16s reference voltage is a true reference voltage which allows for differential inputs. That is a huge benefit if you have a sensor which provides a differential output. What this means is that if your sensor outputs a negative voltage, the SD16 would make your life easier.

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