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Forum Index : Microcontroller and PC projects : WebMite in Silicon Chip Magazine
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
It's a really nice project, Geoff, and a great demo of how to integrate wi-fi control. Unfortunately it would be difficult to justify for my back yard and tiny front garden here in (often) soggy Lancs. UK. :) However, as a general purpose multi-channel mains controller it could very easily be converted to other uses (fish tank timed lighting, CO2 & pump control anyone?) with only software changes. Edited 2023-09-02 18:19 by Mixtel90 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: 847 |
Hi Geoff, Thank you - that's better . . . ! If you are open to suggestions the config menu offers to 'Save Changes' when you haven't yet changed anything? One strange thing was that when I first ran the new setup without the 24V, and just the Pico, it found NTP but then spat out a continuous series of numbers (see below). It appeared to be OK via WWW. When I connected 24V and restarted it it behaved 'normally' and now does so with or without the 24V. Cheers, Andrew A sample of the first pass output: |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
I will have a look at the "Save Changes" question but I don't think that it will be possible to make it work as you suggested. This is because changes to the page (like ticking a box or entering text) are made by the browser and the browser only sends these details to the WebMite when you click on SAVE CHANGES - so the WebMite does not have the opportunity to show/hide the button. This is one of the consequences of having a web interface compared to an LCD touchscreen interface. It looks like I left some debug code in the program and that is giving you all the scrolling numbers. Sorry about that - it is a symptom of rushing too much. I will check it when I get back to the code and fix it in the final release. Geoff Geoff Graham - http://geoffg.net |
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| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 847 |
Hi Geoff, Happy Fathers' Day! Enjoy it! Not a big deal about the 'save changes' or debug code - it is working well. A suggestion if there is ever a Mk2 PCB or to anyone making up the current version: Do what you can to break out pins for 3V3, Gnd, GP16 and GP17. I've just managed to cobble them up to connect an HC-12 (via serial). I've got it working with test sentences. Now all I have to do is attack your code and send messages to the HC-12 as well as the console. This means I can use the WWW to control the watering system from anywhere and add its messages to my HC-12 network for local monitoring (at least a dozen units around the house). (Edit: One of the messages will be using the NTP time to update all units at the same time) Cheers, Andrew Edited 2023-09-03 15:13 by Andrew_G |
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| pd-- Senior Member  Joined: 11/12/2020 Location: AustraliaPosts: 122 |
I have no AC power at the vegi garden and its not practical to try and run mains there. But i do have solar panels etc and a heap of 24v AC solenoid valves scrounged from someware. The solenoids will energize from 24vdc and hold in with 5vdc. Im thinking of using a gate drive ic , 555 timer and two fets to give me my 24v dc 0.5 sec pull in pulse and my 5v hold current I know i could do a 24vdc to 24vac inverter and turn on the inverter with the pump/master ssr " substitute the CPC1965 with a AQZ102 " but i think that would end up being more complex/expensive compared to changing the reticulation controller Any thoughts |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9307 |
Yes, pretty much the same for ANY web-interface thing. Look at routers or OMV(Open Media Vault). You can make all sorts of changes in the web interface, but unless you click on SAVE CHANGES, nothing is applied. Pretty standard for this kind of interface. Smoke makes things work. When the smoke gets out, it stops! |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
@pd-- You could have fun with this... :) For each solenoid, two NPN transistors with base resistors. One pulls in the solenoid directly, the other has a current limiting resistor. Control by switching both on then drop out the direct one after the closing pulse. Now, the control side. For 8 solenoids you need 16 outputs and 8 inputs. This could be a second PicoMite. :) Turn CPU speed down to reduce current consumption - it doesn't need to be fast for this application. You could, of course, use mosfets as they might be better for this application but transistors are cheap. You could also use darlington driver packages and get rid of the base resistors. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
What is the surge current to activate these 24vac solenoids off a DC supply, maybe rather high... Cannot recommend anything without that info. We have gone away from using the 24vac versions, and have moved everything to latching pulse types running off 12V dc. Cheers Mike |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
Is it wise to use latching pulse types for a sprinkler, where a power failure could leave them on? Especially if the individual flow through each valve isn't being monitored in some way. Personally I'm not too happy with using AC solenoids on DC, but if it's what ya got... It's easy enough to add a current limiting resistor. Alternatively a capacitor discharge to provide the closing current. Another problem with AC solenoids on DC is that they have a shading ring or slug.This slows down the release time on DC. It may not be a problem, but it's something to be aware of. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| pd-- Senior Member Joined: 11/12/2020 Location: AustraliaPosts: 122 |
Coil resistance is 53ohms so 0.45A for 24vdc Latching ones would be good but i would need to bye them. The 24v supply is a couple of 12v agm batteries ex mobile base station. charged from a old 250w panel. |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
With NE555s you can make simple switch mode drivers for the solenoids, more efficient than a series resistor. The control signal to the 555 has an additional RC circuit to make the first pulse long enough to pull the solenoid in. 100mS is usually enough. Used this long ago, will hunt for the circuit. |
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Chopperp Guru Joined: 03/01/2018 Location: AustraliaPosts: 1057 |
I've always been under the impression that AC was used to help reduce Galvanic corrosion and/or electrolytic corrosion because of the presence of moisture & current etc so I had a bit of a search to make sure. I couldn't find anything on that. Apparently, 24VAC was chosen mainly because it was easily obtained from the mains. While doing a bit of research, I found among other things this here Brian ChopperP |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
24VAC used to be a very common voltage for control panels and inspection lights. For exactly that reason. :) Also very useful with a dual primary 24V transformer as the control gear can be all the same components in different countries. Not quite as much use in these days of wide voltage input SMPS supplies. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3150 |
Here in Nova Scotia, the thermostats on my 3 boiler zones switch 24VAC to power zone valves. That's a very common voltage for heating and air conditioning system controls in North America. ~ Edited 2023-09-04 01:14 by lizby PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
Most of the combi boilers in the UK use 24VAC internally, even if their external intelligent controls might be at 5V. ========= An idea: 24VDC ----------------------| | 200R | |----------- 1K |, |+ | |/ 330uF |----------| PNP | |/ |\ | input --1K---| NPN | | |\, SOL | | |----------- GND GND When input is low cap charges via 200R. When input goes high cap discharges via sol to energise it. While input remains high 200R limits current to the sol. Select 200R to limit current to the point where the sol remains in. Select 330uF to give a big enough pulse to operate the sol. Edited 2023-09-04 01:43 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
With solenoid coils you have to be aware of the inductive kick back which can be huge. The Watering Controller uses solid state relays that switch on/off on the zero crossing of the AC waveform to avoid this. Geoff Geoff Graham - http://geoffg.net |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
Yep, and if getting the 5V rail from the 24V rail, use a regulator with a 32V or so VDR from it's input to GND as protection. The above circuit should, of course, have a diode across the solenoid to protect the transistor. :) It's only a "back of a fag packet" concept. You can get DC SSRs that would drop straight in (electrically speaking) if you wanted to use conventional 24VDC solenoid valves. Not for using a AC sol on DC though. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| pd-- Senior Member Joined: 11/12/2020 Location: AustraliaPosts: 122 |
Thanks for the ideas all If i can find a DC SSR at a reasonable price i could use a polyswitch with a parallel hold in resister and flywheel diode. |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 6798 |
I hadn't even considered that option. Nice idea! It might need careful tuning of the shunt resistor to ensure that the polyswitch stays just within it's tripped area. The Crydom CN024D05 is 24VDC out, 3.5A, 3-12VDC input would be perfect. However, if GND is common (likely if you are getting the 5VDC from it) then all you need is a logic-level mosfet - you don't need opto-isolation as the gate is driven high or low by the PicoMite output, it can't float once the pin is initialised as DOUT. 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: 847 |
Hello Geoff, I'm sorry to have not replied sooner but I'm only able to get to MM stuff intermittently (I'm sure you understand). I believe I have found the stray debug code: If i > Epoch(Now) + 2 And i < NextUpdateIdx Then NextUpdateIdx = i : print i - Epoch(Now); I've commented out the PRINT statement on the end. I'm now sending status messages to my HC12 network - all good. Thanks! One query if I may? You have the lines: NbrValves = 8 . . Dim Integer Valve(NbrValves) = (10, 9, 7, 6, 5, 4, 2, 1, 1) With the default BASE of 0, I see the need for 9 values but do you intend to have no "8" and two "1"s or are you using that for the master valve? Edit: I'll partially answer my own question. The values of Valve(n) are the pin numbers, pins 8 and 3 are GND hence are skipped - I'm still not sure about the two "1"s, unless that is a dummy? Pin 11 is the Master) Thanks again, Andrew Edited 2023-09-06 08:03 by Andrew_G |
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