enl

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Everything posted by enl

  1. Am I reading correctly that this is with the LM35 not connected to the input pin? In other words, there is nothing connected to the input pin? If this is the case, then the potential on the pin will float, generally to about half of the power supply, give or take (depends on the device) and, being configured as an input, it will have very high impedance, so it will pick up noise. You would be measuring more the properties of the multimeter and its interaction with the floating input than a real potential.
  2. Most of his talk was not about C++, but about how to social engineer others into adopting in a non-supportive environment. It was a religious rather than technical exposition, as many Java talks, for example, also are. As to the data, I buy it. The technical points made are that strong typing reduces run time bugs is true, under the umbrella that only certain flavours of bug are caught, but these flavours lead indirectly to bugs of kinds not caught directly. Another advantage of strong typing is that, properly used, it can let the compiler do better optimization. His test case, a lightweight class, is probably where the advantages are greatest, but this is where, for many embedded applications, the other benefits to C++ are most available. I am not convinced that many of the 'more advanced' C++ tools and abstractions will give the same benefits, other than, with proper design, reduced debugging.With improper design (as one of the questioners put it, 'naive') there are likely to be losses. Some tools impose run time penalties that are unavoidable (often space rather than time) even with strong typing, but many of the standard tools (vector, for example) minimize this hit and save enough in other ways to be a net gain. Well designed standard tools pretty much always beat implementation specific, since they are designed (usually) by a specialist whose sole point is to get the best performance (by some metric) on the specific hardware. C++ provides a LOT of these tools. There are cases where a special purpose tool is better, but these are often brittle when changes are required, and the next revision has a net loss, either in performance (time or space) or in increased debugging. For reference, I tend to be a 'well written C is valid C++' kind of programmer, and use the C++ tools sparingly, especially in embedded work, and am NOT a C++ guru. I am, in fact, quite out of date with regards to the state of the C++ art. I still use the tools as they are appropriate, though. As for the social engineering aspects of the talk, nothing new. Read Dale Carnagie for the same. It is an effective model for understanding others and working with them. Nothing that hasn't been in writing for a good century, and known much longer, though in this case there is the extra fancy four quadrant graph of belief presentation.
  3. Ah. I went through the log and saw that I had added the site as an exception on one machine (one I generally use for such) in 2015. Tried accessing from the shop machine today. I am surprised I haven't noticed before, but, then again, the shop machine has all of three bookmarks in the browser, since it is generally used only for the shop gear.
  4. It appears that 43oh is rejecting https connections (browser: mozilla, system windoze8, urls tested: https://www.43oh.com/ https://forum.43oh.com/ )
  5. I presently both practice and teach, so, in reference only to the engineering side, which is maybe 30% of my professional life these days: How many engineering positions have you had? *4 or so in the last 30 years. Current engineering position has been about 10 years, and is a different field than my degree (mechanical eng/welding is the core scope, but my degree is semiconductor fab/computer eng. I cover a wider base than that, mostly by being liaison between the company and clients or inspectors) I haven't actually worked primarily in my nominal field since the late 1980's. Do you enjoy writing? *to a point What tasks do you do that involve writing in your job position? *Job bids/proposals; RFI/RFQ (request for info/request for quote); evaluations; training materials; compliance materials (safety program, statements of compliance, etc); professional opinion documents; requirements documents; interpretations (code and standards, regulations); documantation/logs for jobs; Do you use the writing formats/styles that you learned in school? *Sometimes. Much of what I do is specialized, though not as specialized as the 2-page-long paragraphs found in military specifications and RFQ's, and much is dealing with non-engineer-tpe, often non-native english speakers (spanish, norwegian, japanese, german, korean, etc), so the formal styles that were focused on when I was in school don't match well. THings have likely changed, though, so the current teaching practice ma be a better match. How often do you encounter a disorganized email and/or document? *Daily. Hourly. Does reading an un-formatted/disorganized document take time away from other job tasks? *Yes Have you ever had to second guess what a person meant when you read their writing? *yes. Daily. Hourly. Did you ever have to ask a person what they meant? *yes Do you proofread your writing? *Yes. I prefer someone else do so, as well. You need to be your own first critic in ANYTHING you do (writing, circuit design, welding, mechanical design, or anything else), but it is easy to be drawn in to what you think you have written. A fresh look helps, especially when it is someone who is not as familiar with the topic as you are. Have writing styles changed in the engineering field since you have started? *Yup. Computers have made a big difference, as has the default software (MSword). Hand written math and symbols died not long after I got out of school, expectation of good formatting of text came in at about the same time. For a time, math was either very well formatted (professional tools were used), or was crap (MSword/macwrite). Now, there is a general mediocrity, but most of the time, things can be interpreted. The indented paragraph has given way to the double line-break. The parenthesized clause has become acceptable (and I have accepted it). Spelling is much better with spell check, though odd errors are more common. In the last several years, I have been seeing more textspeak in non-casual documents (for example: "the site crew will return at a l8er date, no less than 30 days and no more than 45 days after work acceptance, to re-pressure test all welds and mechanical joints".) I have also seen a lot more of the use of verbal crutch sounds in written documents (an RFQ starting "So the scope of work shall be"... with no antecedent)
  6. I spent some time last year setting up an analog meter driver/thermometer for a client, and at the time, I went through my stock of junk^H^H^H^Hreclaimed parts and found a phase angle meter with degree graduations on it. I said to myself "since I alredy wrote the code and did the dev work on someone elses dime, I should throw one together for myself". A year and a half later, the holidays hit and I was looking for something to do instead of paperwork for work. So, I layed out a single sided board (the original was on a launchpad), cut it on the mill, and populated it. There was a couple days in the middle between cutting and populating (the holiday, you know), so I had a surprise. The astute amongst you might notice something missing on this layout, given that this is a low power project that will require stable voltage for the analog meter. Yup. No regulator pads.Finished soldering up the board and sitting there in the tray is the regulator. Whoops. I didn't feel like going whole hog (including changing a setup on the mill) for a board just to hold the regulator and a couple caps, so I pulled out a sharpie, a scribe, and an ancient bottle of ferric chloride. 20 minutes later, I had an etched board that would do the job. Ugly, but functional. The layout for the main board will be revised in case I reuse it. It doesn't look so bad populated. The wire is for USB power.
  7. The board sockets on to the power header The 5-pin with the cable going to the right is for a button and double pole, center off momentary switch for adjusting the scale in operation. The software does linear interpolation from 0 to 100 degrees F, and allows for key points every 10 degrees. The three yellow wires go to the remote sensor (DS18B20). The mounting is leftover oak from redoing a floor. Glued up, planed, bored for the meter and the electronics, and finished to hang on the wall. The circuit board is mounted by putting epoxy in the pocket and dropping it in. Power board on. The tie point for the power line isn't on yet. The face of the finished display: The finish is shellac. I slopped on a heavy coat, light sanded, and then wiped another couple on. Then paste wax. Not perfect, but I banged it out quickly. The meter: Operating. The temp in my shop has climbed to 66F with a lot of help from the electric radiator.
  8. Presuming you are talking about a processor with no support in hardware for division or multiplication: In the absence of hardware support, the fastest is bitwise calculation akin to long division. The cycle is basicly subtract then replace if less, followed by shifts. The structure is similar to long division, and is about the same number of cycles as a single division. This is one-cycle-per-bit in hardware, but a bit more work in software. Figure two shifts, a mask, and a subtraction, and either another mask or unsubracting, plus loop overhead. You may need a 32 (or 24) bit accumulator for the residuals to catch borrows from the LSb. The FASTEST CONVERGING practical method is the Babylonian (divide and average; Newton's method), but that requires division, so is likely to be slower in practice for a 16 bit int, even with hardware division (though it may be close) If exact value isn't needed, or the range is restricted, other methods can be faster, such as a lookup table, but for a 16bit value, the extra code and lookup table overhead are more likely to slow things down. A bit more detail (what processor, what language, how accurate, etc) can narrow it down. This is a case where the wikipedia page isn't bad: https://en.wikipedia.org/wiki/Methods_of_computing_square_roots
  9. Welcome to the preprocessor. I don't know of any more elegant solution as parameters are literal, though there may be one. The second level forces the parameter to be seen as a token itself and be substituted. The initial version did not let the token be seen on its own. I learned the power, and limitations, or macro expansion with asmh on MVS, writing a 12 liner to expand to the twelve days of xmas for a class. The C/C++ preprocessor is more capable, but is still not doing full featured regeps.
  10. I tend to use this style for many things, in particular single thread embedded applications like one tends to have on the smaller MSP430's, but it isn't always my preference. The code tends to be more readable if done reasonably well, with full optimization available since it is expanded by the preprocessor, but inline functions can be just as efficient and are often less likely to lead to debugging issues, making them generally preferable when available, but with the drawback that expansion is not mandatory, so timing is not guaranteed. If forced, you lose some space optimization features.
  11. @yyrkoon They are not cheap, but keep in mind that they developed the software, and, unlike some of the clones (by the magic of google) actually perform as advertised I may be biased, having spent several thousand dollars for significantly less performance during the present millennium for a dedicated device, but I see it as a real deal. With the USB units, buffering is a concern, but none of them (as far as I can tell) are over endowed with memory. They need a USB channel that can suck up data and a host that can do something with it. I have had no issues at 500MHz with a saleae pro on a netbook, but I am not streaming netflix when I am using it. You are looking at low speed UART work, and I would bet a ZX81, or bottom end saleae clone, would be capable of dealing with it. If you are in a time pinch, at those speeds, an MSP430G can split the bits and ram them up the USB line from a launchpad. A 13$ msp432 can do a lot better than that. Given what you are looking at, you are likely to need to write your own protocol analyzer, or see if one is available for a standard device. The Saleae has the advantage of a reasonable dev environment for rolling your own protocol analyzer. The only things showing up in a quick google search that do DALI are pretty far up in price and are locked up against building your own. If it were me, and a deadline was up, I'd call saleae and grab the logic-4 or logic-8 on fast shipping. If $100 is a killer, then you already blew too much time on the project.
  12. I have and use a Saleae logic-8, and have a logic-8pro at work. The lowest end is logic-4 at about $110. For what you are looking at (sub-100KHz) the logic-4 would do well as the sample rate is 12MHz. The logic-8 is 100MHz sample, which is reasonable to about 10MHz systems. There software has several protocol analyzers (I2C, SPI, RS232/standard serial, USB, and about 20 others) and I think it is possible to write your own. I have nothing but good things to say about the unit, and would only give the standard cautions that the units are most useful on a laptop running on battery power to avoid ground issues. A number of the far east import units are near clones, but I can not speak for the quality of them. (one I was looking at had a link to Saleae for the software. I thought that was a bit.... scummy) The reason I went for this is that the reviews were good, the sample rate was sufficient for most of what I need, low V to 5V logic compatible, protocol decoders for things I need are not extra cost, and the software is a good match for what I have used in standalone units for many common features. You can pull the software and play with it without the unit. If there is no unit on the computer, the software fakes it for you for demo. Learning curve is good enough that I have had students using it to debug I2C and SPI in less than 15 minutes. Not experienced students, but first time with anything more involved than blink an LED level students. Edit: watched the video you linked. Looks like a Saleae clone. I don't like the plastic case (shielding issues), but at sub-mhz it is likely not a problem. I haven't used the software he uses. I have a windows machine for such things (due to Autodesk, oscilloscope remote UI, and the microscope cameras), so it isn't a hassle.
  13. What orientation do you have for a project? The capabilities of the processors differ so much that it is difficult to answer your question without knowing where you are going. No sarcasm is intended in the following suggestions: Robotics? You can do multiaxis control in real time. Audio? You can do signal processing within the limits of the ADC resolution. Video? I would guess that you could produce VGA output to run 640X480 VGA at 8 color (one bit per color), or possibly better with some careful programming, and have no major issue producing a videogame. Certainly 320X240 should be straightforward. Using R-2R chains, you could easily produce interesting video output, though anything requiring a frame buffer would likely be out due to RAM limitations. It would probably not be too hard to produce NTSC in the same vein as an Apple II. The gains you get with the 432 include speed, memory, and processing per cycle. With a 430, serious audio isn't really practical. Real video is superstar territory. With the 432, both are straightforward, though not necessarily trivial. Specific ideas in audio: A guitar multi effect, maybe distortion, Wah (a pot on an ADC for bandsweep), flange, and reverb. All are moderately straightforward, but explore different algorithms. Video: One of the coolest thins I saw at a trade show in the late 70's was a video dazzler. Just cool patterns, but really, really cool. An audio input to control an arithmetically produced pattern as VGA output? Robotics: An 8 channel, I2C command servo controller? Do you ride? One of the things I did years ago with a PIC was an electronic ignition for a 1975 Honda CB400F (4 cylinder). Maxed out at about 12000RPM. The unit was tight to about 8000, but had a bit of jitter above that. Drove an output for the tach as well. The 432 can cover other things at the same time, and not lose it's place for the ignition timing. Got a cat? Using the ADC and DSP capability, an ultimate class cat toy? Detect appropriate stimulus (Meow, scratching, othe r) using a microphone, and do something interesting, like turn on a laser pointer mounted on servo's to entertain the cat, and when it gets to a certain point, release a treat? Ok... my mind runneth over. Several of these are things I don't have the time to do. There are many, many more. All of these take more than the 430 can reasonably do (except ignition timing), but none fully explore the capability of the 432.
  14. I suspected this as result of placing an order and getting free shipping. Nice to have it confirmed. The free license for full CCS with the launchpad is also still active, though the checkout added a number of other things for no reason (25 pack of launchpads, full CCS for full cost, and a couple other things), but they were deletable.
  15. Starting point is you have an off by one eror on the loop counter: the test should be "<5", not "<6" as you are trying to do it. But, I think the main issue is that A0, A1, etc are aliases for pin identities, not channel values. You might try: const int analogpins[]={A0, A1, A2, A3, A4}; . . . . for (int i=0; i<5; i++) { sensorValue=analogRead(analogpins[i]); . . .
  16. @@roadrunner84 The circuit can be used for on-off. When a signal is not present, the period is greater than a boundary value. When it is present, the period is less than the boundary value. The advantages to this type of circuit over many alternatives are simplicity and versatility. It can be used for FSK, OOK, and can be used for standard serial, FM and MFM self timed communication, among others. For FSK and OOK, a minimum number of cycles can be used per bit, often only one, if the channel otherwise doesn't affect phase with frequency or have significant filtering. The drawback is that, in applications where you NEED to use a carrier (such as On-Off or FSK) due to channel properties, the processor has to do timing at higher than bit rate frequency and can't treat the input using standard UART tools. The historical application that comes to mind (1977) for this is the TRS-80 cassette, where, rather than use the Kansas city standard, FM (and MFM) were used with a standard audio cassette recorder. Quite reliable and tolerant to timing variation at one transition per bit. Similar methods were used into the mid-1980's by several other manufacturers.
  17. That is what I was describing. The upper section is your minimum (FSKIN side). This is, again, presuming that the MSP430 will do timing of state changes to get frequency. This is presented essentially as an analog connection, but, with a Schmidt trigger input pin, you get zero crossing detection.
  18. Probably not, but the key thing are that a) the signal should center around Vcc/2 (1.5V in a 3V system), teh level should not go outside power supply bounds, and c) the swing should be more that 2/3 Vcc p-p. Additionally, fast transitions are nice, but may not be achievable with audio output device. Using a Schmidt trigger input (available for the timer inputs) makes this less critical. The need for an op-amp would be due to insufficient level from the audio output. A line level output will be about 2.2Vp-p into 50Kohm, but headphone outputs may or may not meet this, and a line level output may drive much higher voltage open circuit. My design would be 5K in series with a 100nF cap (or larger), feeding the center of a voltage divider made with a pair of 100K resistors for biasing. If the input is Schmidt trigger, no issues with biasing to mid range. (For an input htat is NOT Schmidt trigger, do not do this, as the input may enter a state that leads to internal high current and damage.) If the output level into 50K is much less than this (I would be surprised), then a gain stage (op-amp) would be needed. This is not the greatest scheme in the world, but is pretty much what the most reliable cassette tape storage schemes in the late 1970s used. Again, I would tend to stay away from the audio hardware, but if you gotta, you gotta.
  19. You haven't make clear what you mean by audio commands. Do you mean something like tones as used in touch tone telephones? Or are you just interested in getting useable information from the pi to the MSP430 via the audio output in any format at all? or are you just interested in getting data from one to the other and selected the audio output by default? If the first or second, single tone detection isn't that hard. I would use capacitive isolation and protection diodes to limit the signal. Bias with a voltage divider to the middle of the power supply range, and then, using a digital input and timer, time the period. Different frequencies to differentiate commands/states. If you aren't tied to the audio line, using straight digital lines would be preferable. You could use a standard serial, or use SPI, or I2C, or... Straight serial is likely easiest, as that is the least setup from the PI end, and easy to handle from the MSP430 end, since there are a minimum of protocol issues. As you move to an old laptop, it will almost certainly have a serial port available (though it will need level conversion for interface with the MSP430). Audio may be unreliable, especially on older hardware, due to timing issues, etc. Many older devices (post soundblaster) didn't have any audio hardware to speak of. All software driven, like the modems. This led to some, um, interesting, issues during sound production, including poor timing, unpredictable skips from the buffer, and dropped intervals. Serial was was hardware all the way, other than a few cases with 8-bit systems, since so little hardware is involved. By the mid-1980's (80286 era), it was generally included as an integrated part of the system chipset.
  20. pcb-gcode for use with Eagle would by my first suggestion.
  21. The guideline for picking a clock source and the required accuracy and stability is pretty straightforward, but in general, using the DCO is what you want. If you have the crystal in system, the DCO frequency can be compared to it and the bit rate divisor can be adjusted for best approximation. The error rate given describes the accumulated timing error, NOT the unreliability of the line, and can be used to determine whether there is likely to be data errors in transmition due to timing issues. To add a little background, the bits are sent and received in nominally identical time slices. The first edge of the start bit is used to synchronize the process, and, from then on, the receiver examines the line at the middle of each bits allotted time slice. For 8 bit data, with a start and a stop, the total time used is 9.5 bit times, and if the timing slips more than 0.5 bit times in that, then the receiver may lose synchronization on the later bits and the stop bit. This will trigger an error state if the receiver expects the bits faster than the sender provides them, and the bit the receiver sees as the stop isn't the appropriate stop state, and confusion will result from a number of possible ways for the synchronization to fail leading to bits being read as the wrong position in the data. THis 0.5/9.5 ratio means that the maximum difference in bit rate , for reliable operation, is 5.5%. THis isn't bad, but does require a decent clock at both ends. If both clocks are off by 3% in different directions, then there will probably be loss of synchronization. This is the total difference, and, if one clock is very close, the other tan take substantially all of the error (this is not an unusual case, but is not always the case) The clocks for the MSP430 that make sense here are, as you said, the DCO and a 32KHz crystal. The Crystal is accurate to about 0.01% worst case. The DCO is accurate to maybe 3% typical. On the other hand, as you noted, due to the need to produce the serial clock by dividing the control clock, at bit rates that are greater than about 5% of the clock rate, there will be bit rates that can not be generated to meet the requirement. For historical reasons, the standard bit rates don't play well with power-of-two frequencies like 32768Hz. The situation is improved (and this is where the more favourable looking that expected error bound for the crystal comes from) by dithering the clock when you can't get an exact match: The basic rate is higher than needed, and some bits are stretched by a clock to minimize the accumulated error. This works well, but, if done at both ends of the line, can fail when the bitrate is about 1/5 of the clock rate (6Kbs with the 32KHz crystal). This is a rough number, not exact, since it depends on the details of how the bit time adjustment is done. If one end is dead stable, and an extra stop bit is thrown in, it works quite well up to maybe 1/3 of the clock rate (9600bps with a 32KHz crystal). All of that said, I usually just use the factory calibrated DCO frequency and have no problem. I don't even bother with checking the exact frequency.
  22. I have been through a number of generations of in house prototype and hobby scale small volume, and if I can avoid it, I don't do it myself. That said, I don't make a lot of boards anymore, so there is a large grain of salt involved when I say that, with a little care, prototyping on a mill can be viable. It is what I do most of the time these days, as I have the equipment. It isn't as fast as photo, or even toner transfer. There is a mess involved unless dust collection is dead on-- handling the fibreglass dust is a different league than chips and dust from pretty much any other material. What follows is off the top of my head and based on my (probably somewhat outdated) experience. Positives include consistent trace width-- UV is also good, but requires good technique or results can get pretty bad--, no shorts or opens like plague toner transfer and sloppy UV, lower cost than UV if the equipment is already in house, the afore-mentioned alignment positives, no second setup for drilling, and no wet chem. Double sided isn't a big deal with proper use of alignment holes or fixtures, and other in house methods have similar issues. Negatives are dust control, through hole plating (which is the same for most other in house methods), board properties, workholding issues, and leveling. The key to good results is flat and level. A vacuum hold down on a flat bed it pretty much a dead requirement for good results, and accepting that the bed is going to need replacement periodically due to drill damage is a part of it.. If the bed is dead on, then the feature size can be quite good using a 90 degree point tool for the fine work-- depth controls width between close features. I run two tools for clearing: a 90 deg point for outlines and separation of close features (depth controls cut width), and a 0.75mm bullnose for larger area clearing and wide clearance, followed by a drill bit. If the board isn't held dead flat and level, the results will be bad, with nonuniform feature widths and variable substrate thickness between traces. I use a plugin for Eagle to generate the G-code. I would say that the biggest drawback to milling prototypes involving high frequency devices is the change in substrate properties due to the substrate removal, both due to dielectric loss and due to increased moisture pickup. I have never had a major issue, since I have never milled when I anticipated an issue, but I have seen the effects in a few cases and needed to adjust component values to compensate. The key thing is that the prototype board may have characteristics very different from the production board. That said, I don't recommend milling unless there is a compelling reason. For the few boards I do that way, it is ok, and 0.2mm traces on 0.5mm centers is very achievable. I prefer to use a service since I can usually wait. In a pinch, for something simple, I might even use a sharpie and etch, though that is last resort. I can do 0.5mm trace on 1.2 centerlines that way, which is fine for a lot of one-off, since I still use as much 0.1" (2.54mm) lead space devices as I can. I'm old and have poor eyesight. 10 sec with pliers and through hole devices are surface mount.
  23. It already is. They go hand in hand.
  24. The 4017 is a decade counter IC. This means that it has a clock input and ten (actually 11) ouputs. At any point in time, one output is active. Each clock causes which output is active to advance. There are a few other pins, like a carry output that is active when outputs 0-4 are, and a reset input. It has been around for give or take 45 years, and is still useful, for anything from an LED chaser, waveform synthesis, to LED multiplexing circuits. It would appear that the kit was not designed to push you in any single direction, so: I might consider making a puzzle. You have several input devices available (photoresistor, push button, potentiometer, thermistor) and a number of output devices, and could likely come up with something interesting. Other things, more straightforward,, might be a thermometer with 7seg display, A thermostat that is only active when it is dark (or light) , a Halloween prop, a signal control for a model railroad, ......... The hard part is when there are too many options (See _Zen_and_the_Art_of_Motorcycle_Maintenance_ by Pirsig for some interesting input on this).
  25. Has anyone used the Novoton voice modules ("Chipcorder" ISD2360 for example) or similar devices? I am looking for suggestions for an upcoming project, and the price/performance of these looks reasonable, but I have no idea what other options are out there. General outline: the relevant part of the the system will detect roughly a dozen events and play a short audio response to each, playing general background otherwise. Think of something like varied breathing sounds all of the time, with other sounds overlayed or replacing in response to inputs. Total audio is, give or take, 30 seconds, with about a dozen individual responses besides the background. The background sounds will be expanded to fill available device space if more is available, but 30 seconds is the minimum. I am also looking at a WTV020SD type device, but, again, have not used one, and am not sure I am thrilled about the SD card in this system, and don't see that it has any way to layer multiple audio clips. Input? Ideas?