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Forum Index : Microcontroller and PC projects : Advice needed for building temperature control system
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| lizby Guru  Joined: 17/05/2016 Location: United StatesPosts: 3478 |
See "Advanced Graphics Programming Techniques" in the MM+ manual or in the F4 manual. Edited 2021-05-28 01:39 by lizby PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
For bluetooth; HC-05 or HC-06. Simply present as a serial port to the Micromite, some basic config (name, pin etc) and then pair it with your android/tab/iPhone. Easy Android programming MIT App Inventor. Online, needs a Google ID to log in. Compiles to an Android *.APK installation binary. Simple interface can build really nice Android apps for simpler tasks like GUIs and logic for your Bluetooth enable project. did my garage controller with these two in a day from scratch. Bit rusty now coz it all just worked first time so I haven't had cause to revisit much. My 2p Edited 2021-05-28 06:01 by CaptainBoing |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 873 |
Hi Roger, As lizby says its all in the manual. Here is the F4 one (see page 73). Each of the switches/spin wheels etc illustrated above take only ONE line of code to establish. MMBasic looks after the rest behind the scenes. (If I can use it anyone can!) Cheers, Andrew Edited 2021-05-28 08:37 by Andrew_G |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 940 |
Thanks for the links again guys. It's been like trying to drink from a fire hydrant  ... though I've had a good read now and am slowly getting the picture. Pretty powerful devices.Now I need to buy one or two and have a bit of a play. I'm sure there will be lots more questions to come. Thank you. Cheers, Roger |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
might seem like a lot to take in, but there are loads of people here who can provide help and worked examples, just sing out and don't be dissuaded it'll be great |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 940 |
Thank you, I can see you guys know your stuff. Where are the best places to buy these things, are there Aust suppliers or do I need to wait to get from China? Thanks. Cheers, Roger |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2831 |
Here is where I got mine. They also have the 320x240 display that plugs straight in. https://www.aliexpress.com/item/33013274704.html?spm=a2g0o.productlist.0.0.4e0f2303RFzZpy&algo_pvid=73a9395f-ec2b-49fb-99df-1543deb0646d&algo_expid=73a9395f-ec2b-49fb-99df-1543deb0646d-0&btsid=2100bddd16128968983765283e1744&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ |
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| horus Newbie  Joined: 25/04/2021 Location: United StatesPosts: 12 |
I haven't seen any mention in the thread so far of what type of sensors you will be using. Two of the most common types for process control are Resistance Temperature Detectors (RTDs) and thermocouples. Without getting too technical about it, RTDs vary in resistance as the temperatures they are sensing vary. One of the most common types of RTD for HVAC applications is the Ni1000 (Nickel 1000 ohm) two-wire type, which can measure over a range from -50 to 250 deg. F (-45 to 121 deg C). They are generally accurate within +/- 1 deg.F or less once calibrated against a prime standard, and are relatively inexpensive. Thermocouples operate by actually generating a voltage in response to changing temperatures. The Type T thermocouple (Copper/Constantan) is useful at subzero temperatures if that is a consideration, but any thermocouple you select is likely to be more expensive than a comparable 2-wire RTD. You can, however, make your own thermocouples from compatible thermocouple extension wire. Since the Maximite family hardware can sense voltages in the millivolt range, it might be interesting to see what interfacing a thermocouple to one would do. Generally, the lower the mass of a sensor, the quicker it will react to changes in temperature. Sensors of higher mass/greater lengths can be useful for slower reaction times or temperature/surface area averaging (such as a supply air or return air temperature inside ductwork). There are stand-alone panel-mounted controllers in 1/4 DIN, 1/8 DIN, and even 1/16 DIN formats that can provide simple on/off control (via a relay output) for cheap per point, and have their own display panels. For units with analog and relay outputs that can support alarming and other functions the price goes up a bit. These units are industrial process control grade. As an example of what's out there, you might check at automationdirect.com and look for their Solo Basic line of single-loop temperature controllers. Specs and drawings are freely downloadable for the units sold there. These use standard AC "house current" (the units tolerate from 100 to 240 VAC, either 50 Hz or 60 Hz), so no external DC power supply is required. 1/16 DIN is about 48 mm X 48 mm, and these are about 60 mm deep. I don't see where these Solo controllers use Ni1000, but they do provide a wide range of other sensor options, one of which will almost certainly meet your needs (probably the Cu50 RTD or Type T Thermocouple). There are other manufacturers of similar units - this is just an example with which I'm familiar from my work. (Many years spent as an Instrument Technician and PLC programmer...) I wish you all the best in developing and implementing your project. |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 873 |
Rogerdw, Phil99 and horus, BigMik is about to release something that is relevant to the F4 and common sensors. Don't necessarily delay getting your F4(s) but in a few hours you will have more food for thought about sensors. Cheers, Andrew Edited 2021-05-29 17:34 by Andrew_G |
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| horus Newbie Joined: 25/04/2021 Location: United StatesPosts: 12 |
Thanks. I'm not at all familiar with the F4. Looking back, the system under discussion here is a solar heating system, so might benefit from DC powered controls vs. AC? |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8297 |
The ArmMite F4 is similar to the Micromite+ in many ways. It supports both SPI and parallel displays and has the same extended graphics as the MM+. There are plenty of IO pins and a RTC (with battery) on-board. There are 13 pins that can be used for analogue input (would be useful with something like the MCP9700 active thermistor which is remarkably cheap). The DS18B20+ 1-wire digital thermometer can also be used on the normal digital IO pins if you need more accuracy and don't mind paying more. There are two DAC outputs that can give 0-3.3v outputs. An op-amp and a couple of resistors is all it needs to convert these to 0-10v, which is a standard control range for many motor controllers. Add a transistor and resistor to that and you get 0-20mA which is another standard. It's actually a STM32F4VE board. The chip is STM32F407VET6 and you might find the board under that number. (I paid 12.60UKP from ebay with free delivery for mine - in the UK, of course). I couldn't find the specific LCD display in the UK, but I wanted a bigger one anyway. Communication with the PC for programming is via USB serial. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 873 |
G'day all, From sunny but, locked-down Melbourne. This is the release by BigMik I was referring to above. It enables most of the modules we could think of to be connected to an F4, and displayed on the Eastrising LCD (5, 7 and 9") at 800x480 resolution. The screen I posted on the first page of this thread is taken from the test program I wrote to help test Mick's board. His "release" has links to my code (free), and his PCB. I'll post updates to it as people pick up 'enhancement opportunities'. Cheers, Andrew |
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| rogerdw Guru Joined: 22/10/2019 Location: AustraliaPosts: 940 |
Thanks Phil, that helps. Thanks very much Horus, that was a very helpful summary. I had come to the conclusion that I'd need to build a controller and use software to read the temperatures and make the control decisions ... though I could possibly get by with a dedicated module if I wanted to keep it as simple as possible. I really only want the additional sensors to gain more of an understanding of how the whole unit works together ... and then want to be able to access that info easily so I can hopefully finetune it some more. Because this is a one off device built for home use, it doesn't have to be all that accurate ... though to have consistant readings would be helpful. I'd have to have a bit more of a think about the reaction time for some of them as at present some of them are a bit slow acting ... so could do with a better idea just how slow they are ... and whether speeding them up is necessary, or just makes the whole thing too sensitive and bounce around everywhere. And thank you for your best wishes. I may have to yell out and ask more questions later. Thank you for that suggestion and all the details. A bit more reading coming up, though I do now recognise some of the numbers you quoted. Thanks again. Thank you Andrew, I have been hanging out to see what you were referring to. Looks very interesting. I certainly appreciate all the suggestions and help everyone ... very encouraging, thank you all. Cheers, Roger |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8297 |
On most temperature control systems don't be afraid of the sensors being too slow. Usually even the slowest sensor will be very fast relative to the thermal inertia. You'll have plenty of time to take at least a dozen readings and average them. Think how long it takes to get water from 20C to 100C when you boil a kettle - and that's a low thermal inertia system. :) Room temperatures rarely vary much over 5mins. Aiming for fast response times will usually result in some sort of oscillation unless you are a whizz with PID loops, so keep it slow and simple if you possibly can. I'd recommend avoiding thermocouple, ordinary thermistor or PT100 RTD sensors. They are all excellent in their own way but are non-linear so you have an extra job/cost there. The devices I mentioned don't have that problem. (Phew... I thought I'd left all that rubbish behind when I retired. lol) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| flasherror Senior Member  Joined: 07/01/2019 Location: United StatesPosts: 159 |
Anyone else aware of Basic for Android (B4A)? https://www.b4x.com/b4a.html Program android devices in BASIC, gets cross-compiled to underlying Java bytecode so runs on phones/tablets. IDE similar to Visual Basic .NET Many available libraries to add camera barcode decoding, SQLite database, etc Best part is that is is now free, used to be a commercial product. Also other interesting software such as Basic for Arduino (B4R) - create Arduino/ESP8266/32 software using BASIC instead of C. |
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| flasherror Senior Member Joined: 07/01/2019 Location: United StatesPosts: 159 |
Never heard of bypic, but it seems like development stopped in 2018? The firmware was supposedly released but the link doesn't work for me. http://www.bypic.co.uk/index.php/ByPic_Firmware Are firmware/docs for bypic available somewhere online? Edited 2021-05-31 05:09 by flasherror |
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