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Everything posted by enl

  1. @fmilburn: F117 is straightforward.. One of the better patterns is at http://users.ece.cmu.edu/~koopman/airplanes/f117/ There are others, including some very nice origami, but I fear trying to scale origami up to costume size might require 0.5mm aluminum aircraft aluminum skin rather than cardboard to be manageable yet stiff enough when done..
  2. @@Fmilburn - nothing yet. Took my first real time off in 30 years over the summer, and now back to work, so I haven't had time to think. I'm looking for ideas, but not too hard.
  3. Does anyone have interesting projects coming up for Halloween this year?
  4. @roadrunner: Single pnp directly driven by the output of the MSP430 might be ok, but, given the current requirement of the LEDs with all segments on, the base current would likely be enough to cause significant drop at the pin. In itself not a big issue,but the variation between, say, a 1 and an 8 would cause a visible difference in brightness, given the low drop across the current limit resistors. Remember, that transistor is driving all 7 anodes. Also, that would not allow for a higher anode supply than the 3.3V of the MSP430. Higher supply for the LEDs gives more stiffness in the cu
  5. As an additional note, if you are willing to let the brightness be moderately low, you could get by without the uln2803, as each output will only be driving a single led at a time, and use the npn transistor as an emitter follower. The display you selected is 20mA max continuous, 30mA peak. The outputs of the MSP430g2553 can sink 20mA with about 0.5V to 0.7 drop at 3.3V (SLAS735J fig7), and a total of 48mA sink or source (SLAS735J P24), and will have a drop of a bit less than 0.25V at 5mA sink. This suggests to me that if you limit the current of the LEDs to 5mA or so, you can pick them based
  6. Old thread, but I am curious about two things: What was the final purchase, if any? (I may have missed this in another thread, but a quick search didn't show me) and Does anyone have exposure to the Carbide3D Nomad yet? They have apparently been delivering since late '14, but I have found no reviews (in several hours of reading/searching) from an actual user. Lots from the time frame of the kickstarter and just after, but nothing in the form of "I have a production model and have used it". I would love an Othermill but have no interest or need for a Mac to drive it,and am uninteres
  7. @@JohnDough -- The MSP430G launchpad kit includes a 32.768KHz crystal. It is not installed and you will need to solder it on place. I would not call it a beginner soldering job, but it isn't bad as small components go. I would use the supplied crystal, as it will fit the pads on the board and is matched to the internal oscillator driver. You will need to check the specs before programming if you use a different one, as you may need to change the load capacitance from the sample code. ULN2803 is fine with the LED displays you selected, but see the following for why I don't think you wan
  8. http://forum.43oh.com/topic/2896-post-a-pic-of-your-home-work-bench-get-a/
  9. I have not tried Energia, but the test machine at work has had a number of issues with a variety of software. One of the students giuneapigged with Eclipse and had no end of trouble a few weeks ago, and ended up backing to win8. I don't know what the issue was, but I am not going to go to 10 for other reasons (license conditions among others)
  10. Needed a new board vise that would sit flat. The old linemaster is not quite the thing for some jobs, and is kinda a pain to crank, though it is real solid and heavy. This was out of the scrap bin in about an hour. 1/2" square tube, 1/4" rod, a spring from the junk pile, and a thumbscrew. Mots time consuming part was tapping the holes. No tools more advanced than a handheld drill and a hand tap and hand die (for the end of the rod). There is a nut inside the tube to jam with the nut on the rod end. I was trying to figure how to mill a tapered grip on a chunk of ABS from the scrap bucket, t
  11. DIY camera for the 'scope. The 'Scope itself is a Nikon stereo zoom I picked up for a gloatable low price, that has an oddball camera port. Two ports, one left and one right, but the optics for them are non-standard, so no way I can afford commercial cam optics. Best price I have found used is still over $1000, without a camera. This is trial run for a better quality and resolution setup.
  12. Did you enable interrupts? ( _BIS_SR (GIE); )
  13. Well, finally woke back up, got real work done (one of the ways I make a living), and for those that are interested, have pics of the $3ish junkpile microscope cam. I did finally get the focus in in sync with the eyepieces. Just a real tight focal plane. If anyone wants pics and complete description, let me know. Otherwise, attached is a pic of the final product. And, yes, that is a handlebar clamp. The second time I pulled the camera off and had to try to re-align and find the focal plane, that went on to make it easy to find location. I was going to make up a shim to go between the registrat
  14. Since this thread is back to life: Right now, I am going to bed. Spent the night making a microscope camera from an old webcam. Optics from the defunct NTSC cam that came with the 'scope. Needed to set p so the optics form an image and mount the sensor of the cam in the image plane, while making it adjustable enough to align. Junk box to the rescue. Worked overnight because a) I started late afternoon, 2) it is useful to be able to turn on the dark, and iii) a lot of fit and fiddle with the lathe and waiting for epoxy to set up. Cam has such a small sensor that full frame is about 4mm
  15. Since this thread is resurrected, might as well mention what I did on my summer vacation: 2452 was the processor of choice, as I had a few around. Someone with more money that reason was the client. A roughly 100 yr old power plant D'arsonval movement was the victim. A DS18B20 was the imperitus. Money in my pocket was the result. Eventually (when I finish the setup in my own house, since I got paid to do the work and marginal cost for me is scrap bin plus a little time) I will post. Not original concept, but ideal for the 2452.
  16. There really isn't much to it. In many contexts, it can get quite involved, but in a straightforward application on a small processor like the MSP430, you can keep it simple. Def (working): Semaphore: A signal made available by one function for to indicatte a status or condition to one or more other functions, outside the standard call-return or exception models. For your application, I would define an external (global; outside all functions) volatile (signal to the compiler that the variable can be changed from more than one place in an unsynchronized, unchecked, and independent m
  17. Looking at the standard on the NMRA site (S-9.1 - http://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-9.1_electrical_standards_2006.pdf), the timing isn't terribly tight. If I were going to implement this, I'd use a single timerA and deal with the outputs in an interrupt handler. Let the timer free run in continuous, and use CCR1 to set the interrupt time. Each entry to the interrupt, add the appropriate time to CCR1 and change the state of the output as appropriate. There are a number of ways to sequence the bits. I would probably not do it in the interrupt routine. I would u
  18. Never had a need to look at the one-bit level shifters before. handy little buggers, they appear to be. Ordered a couple different flavours to play with. In the mean time, what I have is not quite making sense, and I figure I am missing something in the documentation. What I am seeing is that, if I set REFOUT in the ADC10CTL register, while the appropriate ADC10AE bit is not set, the output hangs at a stiff 750mV rather than being pulled low as the P1OUT bit specifies. Doesn't even float. It is stiff against 500uA. My initial thought was modulate the ADC10AE bit to switch between the P1.4
  19. Ok. That woulld allow me to use hardware PWM. Any ideas on a level shifter that will go down to 1.5V? Not sure if I love needing another device, but would definitely simplify the software.
  20. Using a g2553: Any suggestions for doing PWM using the internal reference for the high so that Vcc doesn't need to be regulated? Battery powered application so not using a regulator is desirable. Only way I can come up with is use P1.4 as the PWM output, after setting up the reference, toggling ADC10AE.4 in software, otherwise configuring the pin for output and a value of 0. It works, but it is kinda ugly, so a more elegant solution would be nice. The application is driving an analog meter movement, so the current is in the ballpark of 200uA full scale.
  21. Code is attached to the post in the halloween contest thread. Take a look at that first (about halfway down.. the file is "main_revised.c") Note principally the setup at the start of main, and the timer interrupt service function. The interrupt function outputs new state, then counts clock ticks. At the end of PWM cycle, it resets the counters for a new cycle, loads PWM values for then new cycle, and raises a flag for the main to update the PWM values for the next cycle to follow. Note that the first thing done is update the outputs. This minimizes jitter. Not as good as hardware PWM, but clos
  22. You followed up while I was typing. Using the tip31c will require a different setup to drive it, as they are relatively low current gain. Darlington using a 2n3904 for the first stage will do fine. Also, you CAN do more than one PWM, even on the most basic MSP430g devices. The 'g2452 has two hardware driven outputs for the single timer_A (each of which can be one more than one pin), for example. Other higher level devices allow more hardware PWM. That said, using software, you can do as man as you want. Somewhere in the past ( http://forum.43oh.com/topic/4511-ended-oct-2013-43oh-ha
  23. Absolutely. The style of strip you are using is about the easiest to control. Without getting into details of what you did (since you didn't provide the code, say what processor you are using, etc), I'll go over a few things related. Assuming that you understand how PWM works, the key questions are polarity for the drive (is the LED on when the output is high? or when it is low? The adafruit sample should be on when high), what gate voltage is needed to enable the MOSFET (assuming you are using the same device as the tutorial), what pins can you use for PWM, and are the outputs properl
  24. I generally use a transistor array or LED constant current sink driver and run a matrix common cathode, using the microcontroller outputs for the anode drive. One of the go-to arrays I use is uln2804 (darlington array). Unfortunately, few microcontrollers have the ability to either source or sink enough current to drive an array at significant brightness without external drivers.
  25. I will freely admit that I am still a DIP guy. Several reasons: I'v been around a long time so familiarity is a piece; I can see a DIP without the microscope; Most of what I do anymore is personal or for teaching, and being able to pop a 2553 or 2452 or.. into breadboard with a small cap an a resistor and nothing else, rather than make up a PC board, is a big benefit.
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