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EngIP

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  1. Thanks for the replies guys. I've used a cheapo PID controller I had lying about, which is giving me +/- 0.5 degree C error, which is more than sufficient. Implementing the control on a 430 would have meant doing all of the ancilliary work, such as power supplies to the chip (240V AC down to 4V DC), interfacing GPIO to real world devices (alarm relays, contactors and the SSR), and building a HMI into the system - interesting from a personal point of view, but time consuming from the commercial viewpoint. My oven hasn't got any desireable features yet (timer, power consumption monitor, pre-sets etc.) so there'll definately be a 430 going in there sooner or later, just need to find the time first!
  2. EngIP

    Looking for FPGA suggestions

    I've used Altera chips at Uni, but I think (as @@jpnorair said), the decision is more VHDL/Verilog than which chip/board. The QuartusII software is quite nice, and Altera provide online training information which is very useful (Altera University I think they call it). I just started getting into it as time was running out, but it's so mindblowing when you start to grasp the capabilities of the chips - Writing a VGA driver that uses less than one percent of a chips resources was staggering to me (then again, I'm impressed by the "browning" button on the toaster so don't let my enthusiasm hold any sway). Anyway, Altera, QuartusII, free online training = easy FPGA's
  3. @@yyrkoon - To my untrained mind, heating is heating, be it a pizza oven or a furnace (well, maybe not a furnace). Like you said, only the profile changes really. In the powder coating case, the profile is as simple as "get to setpoint, stay at setpoint for 15 - 25 mins". The items being heated might weigh 100kg/200lbs, and the oven is 6ft x 6ft x 8ft, so this isn't a fast responding process. The only things to really worry about are overshoot and excessive oscillation around the setpoint, but deviation of 5 degrees is acceptable. 200 is the max temp required, and I know my current set up can achieve that. PWM switching would be in the order of seconds rather than anything sub 1Hz. But these are all issues catered for by PID controllers, designed for the job and used over the world - I'd feel like I was building my own just for the sake of it. On the other hand, using a homegrown PID gives a lot of advantages for reasons I've mentioned. My main concerns are with driving the elements. Is Passing 36A at 240V through a 40A rated SSR better than passing 3x12A through cheapo 25A SSR's? Less SSR's means less parts to fail, but at the expense of higher cost parts, and increased disruption in the event of failure. I guess my problem is too many decisions, not enough knowledge! Thanks for your input
  4. @@yyrkoon - This isn't a reflow oven, it's a curing oven for powder paint (powder coating) - I've dry run it up to 200 centigrade, the elements perform fine (though I'm going to add another 9kW to ensure continuous operation, giving me a blistering 27kW of heating elements). IR is no good for my application, though it is used in powder coating. @@spirilis - This is the thing - I'm sure I could get a working PID control loop (or PI) with the 430, but I'm not convinced it's the best route forward when I can steal my Eurotherm 2408 from the existing oven. The price of the thing suggests it's going to do a better job than I can, and it has self teaching setup. However, using an MSP430 will give me full control over other factors (such as timing, measuring uptime/power monitoring, preset curing profiles etc). Sorry for my vague question (as always) - I tend to ask first and think later! Now I think about it, my question is more general electronics than 430 related anyway. I'll go with the dedicated PID, and integrate a 430 based supervisory system after - this should give me the quickest time to deployment whilst maintaining an option of flexibility with the system control (as opposed to temperature control). Now to decide how many SSR's and how cheap dare I go? Crydom or eBay? 1 per phase, 1 per element, individual element control or group? Maybe even use a contactor! As before, feel free to chime in with your experiences or advice
  5. I'm currently in the middle of an oven project (those with good memories will know I started something similar about 3 years ago!). It's using electric heating elements and thermocouples for the temp. sensing. I'm liking the thought of a complete MSP430 controlled system, giving me masses of flexibility with control options. On the other hand, a bespoke PID controller will have significantly better control algorithms, and probably better temperature control. Then there's a third option - use a PID controller to control the heating elements, but use a supervisory 430 to handle displays, timers, data acquisition etc. I'm fairly certain I'll use SSR's for the elements, probably one SSR per phase (3 phase), or maybe one SSR per element (6 elements but capacity available for an extra 3 elements (@ 3kW each)). I'd appreciate general thoughts on this project, if anyone has a simpler/cheaper/safer/better solution I'd love to hear it. Also, what's the best way of driving the SSRs from the 430? I was thinking MSP>transistor>SSR, but again, suggestions are welcomed. Any combination of PID/430 can be used (e.g. PID output fed through MSP430, or PID output fed through 430 controlled relay). So...comments and criticisms please
  6. Time based is what I'm going for, all I want to do is see how well it can perform. As a minimum spec, I'd say <3m accuracy in open field conditions would suffice. I did originally intend to integrate various other factors in, such as predictive algorithms, signal strength etc. - but it would have forced my hand with the project, whereas I want to keep it as open as possible (then suggest an application once I've determined the capabilities). I hear what you're saying with frequencies, I'm hoping I can get a proof of concept with my 869MHz system, then suggest lower frequency/higher power to improve performance. Getting permission to operate at anything other than 869/433 would have proved too troublesome I'm afraid. I can't remember why I didn't go for 433MHz though - maybe I wanted to get some use out of my Chronos' . I've done a bit of testing with the Anaren booster pack (869 MHz), and I'm getting a usable amount of range out of it - though it's far from perfect it'll hopefully suffice for proof of concept. The 169MHz band would probably have been a better alternative, though I might have struggled to get cheap plentiful parts (as opposed to the 869MHz). Thanks for the advice, it's certainly an interesting area of electronics.
  7. Good stuff, thank you! I'm happy to ignore the algorithmic side of things, there's people who can do a far better job of that than me. My interest lies in the distance measuring - TOA, TDOA etc. I guess there's a limit to the cell sizes, but 1/50 @ 20m cells is very impressive! My application is distance measurement in high multipath environments, restricted to the narrow bandwidth and power available in the license exempt spectrum (ISM 869MHz). That said, I can transmit at 500mW in the 869.4-869.65 band. which should be enough for my purposes. I'm avoiding "special hardware" (corrolators, phase detectors, antennae arrays etc.), and just going for a simple approach, using two-way ranging. Any thoughts or suggestions you have for this application will be appreciated.
  8. Just to ask this again, in case you missed it - I'd love to know how you went about it and how well it performed. Of course this is an open question - anyone with ideas or experience please chip in. Sorry for the thread-jack OP, but I think it's in the same area as what you were asking, but if you'd rather I can start a seperate thread.
  9. To what resolution/accuracy, and for what environment? I'd be very interested in anything you can share.
  10. I'm attempting something similar, but using RF only. As has been suggested above, the trilateration aspect might be best implemented on a more suitable device than the MSP430 (though I'm sure it's not impossible).
  11. EngIP

    Basic timer usage

    Thank you! I did think it strange, but the code example I was using just used the '=' operator, so I blindly followed. Again, thanks, all is working as expected now
  12. EngIP

    Basic timer usage

    I want to "clock" how many cycles it takes for my code to get from line x to line y. Could someone please advise me on how to set this up. I've tried TACTL = TASSEL_2 + ID_0 + MC_0; // Set up source (SMCLK), divider (1), timer halted TACTL = MC_2; // Start timer in continuous mode __delay_cycles(2345); // Do stuff x=TAR; // Copy timer register into x TACTL = MC_0; // Stop timer As it stands, x always has a value of 0. Obviously I'm missing important code, but I don't know what. Code examples I've seen use external signals, but I want this to measure from internal states. Any help? I can't really use an IDE function to do this, as I'm wanting to measure the clock cycles between sending a message over RF, then receiving an acknowledge. What I want to do in pseudo code. 1. Start timer 2. Tx over RF 3. Rx Acknowledge 4. Stop timer 5. Read timer. Thanks in advance
  13. You need the contrast pot. If you haven't got the contrast set, you'll either see all black squares or all clear. If you don't have a pot handy, you could use 2 equal resistors, lead 1 of resistor A to Vcc, lead 1 of resistor B to Gnd, and the other leads of the resistors connected together at the contrast input. You might get lucky
  14. Also, if it's just the one or two you're after, TI will supply you with a free sample - find the product page and request a sample from there. As advised above, go for the MSP430G2553 - it's the daddy of the valueline chips. Personally I'd get a new 1.5 Launchpad - it comes with a G2553 and one other decent spec valueline chip, and you get the redesigned layout which allows for the jumpers to be rotated for hardware or software uart.
  15. EngIP

    Anaren TI CC110L RF AIR Booster Pack

    Plenty for me to chew on there - thank you
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