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Everything posted by enl

  1. GIven your goal of 5 years a set of AA, wake up a few times a second, and +-30 min per year (1 part in 20000, or 57ppm) I would do the following: Use 32Khz crystal Depending on how much and what needs to be done 10 times per sec, use the 32Khz as system clock. For roughly ten rounds of work per second, this gives you 3277 clock cycles to work with each timeslot and very low power. If the work is less than that, you go to sleep and let the timer interrupt wake up. If you are going to cut it close (3000 cycles or more), it is a toss up whether it is worth the sleep. If you need to do
  2. Both @igor and @abecedarian give good advice. If the counter is not declared as volatile, the loop will be optimized away, as the compiler can tell that nothing is done in it. (the following is oversimplified, but good enough first approximation) If nothing is done in the loop that has a permanent effect relevant to the loop (like modifying a variable that is used outside the loop), touches a volatile item, or calls a function that the compiler can't determine has no effect, then the compiler will optimize the loop away. You need to do something that the compiler doesn't know is useless. T
  3. enl

    Starting Off

    Background on how these boards are setup, and why: At the physical level, there is an IC, packaged in a plastic block to protect it, with pins coming out. Most processors have more than one configuration for how thephysical pins are connected to the logical construct we talk to with software. Some devices, like the arduino, tend to group the pins on the board by functional capability, even when the underlying IC does not... the designer routes the wires to make locical sense for the user. The programming platform may support the labeling, or may not. Often, there is a choice, though it
  4. good to hear. Debounce can seem like magic. Quad encoder with decent switches gives redundancy (via 4 states) that helps a lot. Old school with sliders, like the early microsoft mice with brass contacts sliding on a pattern on a PC board, were horrid to decode, as it was ALL bounce. I hated those mice, and I hated when I was working on things that used the guts of one for an input device.
  5. Never underestimate the ability of humans to play the fool to a foolproof plan
  6. I would guess at bounce issue as well. Simplest solution is an RC filter. Several ways to do it, but I tend to avoid the simplest, which is putting a cap directly across the contacts, unless I know that it is a very limited use device, as this method tends to destroy the contacts quickly. A three resistor solution is better, and properly tuned generally satisfactory. (see attached MSpaint sketch) Adjust the cap as needed. The Tc as shown is about 1ms, which is my usual starting point. This is not the best way to go for production devices, but is quick and simple for a one off, and a good c
  7. Not a bad presentation. Seen a lot drier in a webinar (like the dozen or so compliance ones I have to view at work every year), and seen better. A bit of fresh info, but not a lot for someone who follows the related TI tech updates, a none of the devices/technologies discussed are new release. Nice to be able to submit questions, tho
  8. enl

    halloween 2014

    About 2.5 months to go, and I am ruminating on what to do this year. Last year was last minute for me, and I want to do a bit more prep this time. My goal is still subtle. Yes, Iwant to actually creep out and scare people. I want to hear comments about not coming to my house again. Most of my neighborhood is very campy, so I aim to be the house described as "there's one on every block". Funny thing is that the little kids get a kick out of it. The teenagers andsome parents are the ones that freak. Last year it was the creepy eyes. Trying to figure out what to add this year. Anyone else
  9. with launchpad and g series, I would use 2553 and serial for display, as there is a hardware serial peripheral on g2553, and the 32khz crystal for timebase. Use a HW counter to interrupt after 32768 ticks for counting seconds. Buttons would be interrupt driven. Note that debounce can be hard. Ethernet: lots of options, and I can't give advice. Not limited to ethernet? might go serial? Easy, and faster than human trigger to stopwatch. Multiple serial is fairly easy: one HW, one SW using a timer..
  10. Only one I have is doing something right now (display is on temp/humidity monitor... cat is on lightning bug) or I would offer. Unfortunately, gravity happens.
  11. Finally got done with job in a power plant (replacing piping manifold to turbo on 3000HP 8cyl diesel) so now, trying to debug a Monroe LA5-200 calculator. Don't have a ton of hope. It was sold as 'working', but smoke came out the moment it was plugged in. Got 75% off due to smoke, so not a big money buy. May need to rewind motor. Eventual goal is to us it as an ALU for something. Mechanize button presses and some means to read the display, counter, and, maybe, internal register. Thinking mag sensor to count teeth as they go by or maybe measure distance as the drums shift sideways.
  12. s@simpleavr: Actually, with a little code, you do have a scope, or an application suited substitute. The setup you have, with debugging interface, can be used to probe the behavoiur of the front end. (Now, back to putting the new floor in my office. Only about 100sqft left on the finish floor. Oh, my aching back.)
  13. @simpleavr: This is actually a hard problem. I played with it years ago for a directional phase-array microphone, which is actually easier... direction is determined by calibrated delay in each channel. Your mics look to have a separation of about 100mm. This is the wavelength corresponding to, roughly, 4Khz from the side aliasing to straight ahead, or about 40Khz from 6 degrees off center line. (I was going to go into a long explanation/analysis, but I will keep it short: My current project calls and it will take a while to formulate a clear explanation) Short form: you need the
  14. Unless the rules have changed recently, ANY electronic product is going to need to go through compliance, wireless or not, to insure that it meets stated interference spec, etc. Battery operated MAY not need to go through UL, etc. Best bet is talk to a compliance pro. Been a few years since I followed the details, but one of the best resources was _Conformity_ magazine (I think it changed hands and name a few years ago.... _In_Compliance_ now maybe?)
  15. non-spikey: plastidip. I used to use the brush on, but a few years ago found that there is no a rattle can version.
  16. Internal oscillator is RC, not crystal. It is spec'd at about 3%. It may more stable than that at const temp and voltage, but isnt a gaurentee. External 32KHz xtal is recommended for betterthan this
  17. Make temperature a volitile. It may be getting optimized out as it is never used
  18. enl

    LCD backlight off

    What model s the LCD? Many have software control for the backlight. If not SW control, then transistor switch is appropriate. Traditional is an NPN transistor to ground... the anode of the LED is connected to power, resistor cathode to transistor collector, emitter to ground. Current to base turns on. Use a limit resistor to control base c urrent.
  19. Is it possible to selective power down the other devices rather than the entire board so the processor can LPM?
  20. I went through this a few months ago. I can tell you what I bought, and why, but can't really make a recommendation without knowing more about what you will use it for. Background: I replaced a 50yr old vacuum tube HP scope, 500Khz bandwidth analog scope. It was usable, with a little care, to about 10MHz, but required gain compensation and had significant distortion for non-sine wave forms. I looked at used and new, including Rigol, Siglent, Agilent, Tektronix, GWInstek (GW-122 portable), and a bunch of others, including ultracompact types like the Nano, even some single channel. *
  21. The beauty of functionality
  22. Measuring temp (duh!) in equipment enclosures Temp monitor for the regulator/charge controller on one of my bikes LImited temp range tempco cancellation for fixed resistors (there are better ways for wide temp range, but none are cheaper) Feedback device for a heated box (constant temp environment for a thermocouple cold junction and amp) The possibilitiies are endless..... When I am worried about accuracy, I do prefer, at slighty higher price, the integrated temp to current devices or direct digital output devices (like DS18B20), as they tend to be more stable and have tig
  23. Without having investigated the details for the board myself, I can make a few suggestions: Check the temp range for each critical IC on the corresponding data sheet. Don't worry about those that are not active in service. Look at the LP spec for the board and identify the relevant components and check their temp ranges. For the EXP430G2, there is pretty much nothing that can't be isolated during run. THis means only the MSP430 and the substrate matter, which should be fine to 85degC operating. Others may vary. Most substrates and components are ok to at least 125, often 150, deg C
  24. In the last few weeks, the option of the QMath lib from TI has become available for the G-series and other low end MSP430. Disclaimer: I have not used it, but the docs and benchmark numbers look good The function that covers your application is _QNatan2 (or IQnatan2) for angle output, or _QNatan2PU (or IQNatan2) for cycles per unit output. The benchmark numbers look good, but are not int he ballpark of table lookup. If the amplitudes are not fixed, then this is likely your best option. Code size up a bit, but not as much as with floating point, and no table needed. See: http://
  25. What drivers are you trying to install? For CCS? Just COM driver? other? My first suggestion is try other COM ports. I have no problem on either my 32bit (netbook with starter) or my 64bit (win7 pro laptop) win7 machines. If no joy on any USB port, I don't know what to suggest without more info. Reason for suggestion: I am having a similar problem with a win8 machine (says not found on com port). If I plug in to the USB hub or the port on the from of the machine, problem. Plug into port on back (usb3.0... separate USB controller), it is ok.
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