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T962A Controller Drop-In (using *PIC32MZ*)

This is a drop-in replacement controller board for the T962A reflow oven, using the PIC32MZEFH as the CPU.

Similar projects worth following
PIC32MZEF CPU @200Mhz

8KB eeprom (256x32), from (256x8)

4 Max31855 on-board TC Sensors (K-type), upgradable to 8 with expansion board

on-board DS18B20 1-wire Digital Thermometer, for CPU fan control

PWM control of CPU fan (6Khz PWm)

120VAC Phase-cut control of COOLING FAN for true speed control
(via 8-bit DAC and FL5160 AC Phase controller)

PWM control of heater/SSR (10Hz PWM)

USB & RS232 on-board interfaces (RS232 3.3v/5v selectable)

5v & 3.3v switching power supplies

Unused PIC32 I/O pins brought out to header

Expansion Headers for future use

** board is fully grounded and can be screwed/grounded directly to oven case **

** AC is fused on board for short protection, etc **

** USB & RS232 Not yet coded up in software **

*** software port from Werner Johansson's exceptional work on the original T962A improvement software.  I cannot overstate how much credit goes to WJ for his oustanding work on making this software.  I would not have even attempted this project without his work, and all of the contributors, RE work, etc everyone has done in making this oven usable.

***

This port contains simplications of the Temperature sensor code, unused things have been removed, etc, etc, and also due to the more straightforward hardware of the PIC32, many of the hardware interface functions have been changed (ie SPI-2-I2C bridge code, etc all removed).

But overall, the functionality is the same, with all of oddities of the original chinese board removed, like the TC 'gain' and 'offset' params, which are no longer needed.  The MAX31855s contain their own internal Cold-Junction compensation, therefore, no CJ calculations need to be done to the TC readings from the 31855s.

There are spots for '4' MAX31855 sensors on the PCB, a minimum of 1 can actually be used, but the oven has 2 installed, so makes sense to at least install 2.   The other 2 on-board sensors are labelled as 'PCB#1' & 'PCB#2' sensors, works well to use these as 2 add-on K-type TC's for measuring temp real close or on the surface of the target PCB itself.

Also, the on-board DS18B20 sensor is now ONLY being used to drive if/when the small 'CPU FAN' comes on, and the speed (PWM), etc.

The COOLING FAN setup uses an 8-bit DAC feeding the FL5160 phase-cut controller, providing true AC voltage/speed control using mosfet switching.  This allows the speed of the AC fan to be controlled just like a real AC dimmer, controlling how much AC voltage is 'turned on' for each AC wave cycle.  The only issue with the AC fan in this setup is that they don't even spin when the AC voltage goes too low, so running the coolfan at speeds under around 40 or so on the speed setting will produce almost no fan rotation, or none.  

** This COOL FAN setup works very well for running the oven in a 'convection-like' setup, where you keep    the COOL FAN running continuously during baking
**

** NOTE:  The stock metal fan this oven comes with is quite heavy and slow to react, I replaced this clunky    fan with a very cheap 120VAC 80mm fan from amazon.com, which works so much better and runs better at       lower voltages.
**

The old setup using the TRIAC was using 'proportional AC voltage' control, which is very ineffective at controlling speed of an AC fan.

******** <><><><> RECOMMENDED OVEN CHANGES <><><><><> ******************

1) Fix the earth grounding issues with chassis paint covering where the earth ground is screwed to the    chassis.  

2) Replace the bulky/metal 80mm cooling fan with a lighter/plastic fan (that has better response over AC    voltage range)...

   example:  https://www.amazon.com/gp/product/B004YTSB7C/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

************************************************************************

***** FYI:  *****

You do NOT need to install the felt 'insulating washers' that the OEM board was using, this board was designed to be properly GROUNDED to the oven chassis.  

 It is also HIGHLY recommended to properly fix the grounding issues that others have shown in various cleanup/etc videos/online posts, where the GND wire on this oven is connected to a screw/washer that doesn't touch bare metal, but instead painted metal.

**************

T962A_Controller.production.hex

latest production build (flash right to board)

hex - 161.03 kB - 08/02/2019 at 19:07

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Portable Network Graphics (PNG) - 434.40 kB - 04/05/2018 at 20:21

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Portable Network Graphics (PNG) - 999.94 kB - 02/07/2018 at 23:37

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sheet - 111.66 kB - 02/07/2018 at 23:37

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  • 08/02/2019

    PhillyFlyers08/02/2019 at 19:09 0 comments

    Thanks to Keith's comment, never realized you were stuck only being able to edit 'custom profile #1' as there was only ONE custom profile on the original UE firmware update, since the stock board had limited eeprom space.


    Fixed the simple bug, now you can edit all 10 custom profiles, and they save, etc.

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KeithF-git wrote 08/08/2019 at 15:42 point

Well Mike, everything is dialled in and set up and working great. I really like the way the two PCB level thermo-couples sum up with two built in ones giving an absolute and accurate oven  temperature. Really clever stuff - Well done.

I settled for a min fan speed setting of 3 which seemed to quell the fan growl on low speed.    

once again Thank you and our Swedish friend for such a splendid upgrade, I'm delighted with the outcome. And here was me thinking the Swede's were only good for stinky tinned fish, ABBA and Volvo Cars ( joke ) - how wrong am I. 

  Are you sure? yes | no

KeithF-git wrote 08/04/2019 at 16:28 point

Just finished and tested your new OS - Works an absolute treat ... Don'know if I'll ever fill all 10 Custom Profiles, but I'll sure as Hell use 3 just for Pb Paste re-flows and possibly another 2 for non-Pb alloys/

Need to put it all back together again and have a fiddle about with this min fan level setting to see how low I can get the fan  to run without growling.

Thank you so much for your help and efforts, it really is appreciated. Just need to wait patiently for another firmware upgrade to activate the USB Port and allow me to log the time/temperature data on a chart. 

I purchased one of these EST upgrade kits a while back but i didn't like the idea of hacking the TRIAC board in half. Never liked the idea of having TRIAC's control a couple of heaters and a fan and a non graphic display. It does have a USB Output and a log file. though.

  Are you sure? yes | no

KeithF-git wrote 08/03/2019 at 21:15 point

Hello again Mike, to be honest I played around with the minimum fan speed setting in the beginning but couldn't draw anything conclusive besides at the time it kept munching its way through FETS for breakfast, lunch and Dinner. ( i had loosed off the Earth Bond to the upper case without realising what the consequences would be)  Now that I have a little more information on the fan speed I'll do a little more digging and see what effect there is.

I'm not too sure as to where you say, 'Run the Fan at 60, 70, or 80 I'm making an assumption that this is a decimal graduated value as I'm almost sure my Minimum Speed setting is graduated at 0 to 10, and in the beginning not being too sure of what was happening, I set it at 5 and haven't gone back to that as yet.

I'll have a poke around with it after I have ported your new code onto the micro and get back to you.

  Are you sure? yes | no

KeithF-git wrote 08/03/2019 at 08:16 point

You write: what's your min speed where it actually spins and doesn't grind?

 It is difficult to accurately say, I'll see if I can put the Tacho on it when the next Fan arrives from CN. This really is a cheap one (6 USD) so with a bit of luck it will be a lightweight plastic one which will run at low speeds. 

  Are you sure? yes | no

PhillyFlyers wrote 08/03/2019 at 13:48 point

Hi Keith,

You don't need to do anything that complicated, the 'min fan speed' in the settings is all you need to play with.... I think I set the default in the code to '80'.

So this code is setup to always run the fan in a 'convection' like setup, *IF* you set that 'min fan speed' to anything above '0'.

So when you are running a profile, the 'min fan speed' is always checked against the 'called for' fan speed, ie the fan speed that the software determined it needs to run.  If the 'min fan speed' is higher than the 'called for' fan speed, the fan is then set to min fan speed, ie 'convection'.  ie always keep the fan running at the 'min fan speed'.

And of course you can disable the 'convection' by just setting min fan speed to 0, then it only runs the fan when the PID (software feedback stuff) determines it needs to run.

So to test your fan 'grinding'/making noise but not moving, just set your min fan speed to start at like '80', and then just start to run a profile... during the initial ramp up phase when it just needs to heat, there is normally no fan, but with a min fan speed, the convection will be enabled and it will run your fan at whatever your min fan speed is..

So play with that number and see what the lowest is you can go where it actually spins?

For my cheap amazon fan I linked, it's around 60-70, any lower and it's not enough AC voltage to spin.

- Mike

  Are you sure? yes | no

KeithF-git wrote 08/02/2019 at 19:53 point

I will flash the micro in the morning. I need to strip it out anyway as I'm punching some holes in the side to take a USB Passthrough connector and a couple of K Type Thermocouple sockets. 

I know there is no code for the USB and the RS232 ports but perhaps when you find some time you may consider writing some Logging Code which can be ported out to a data log program on a  PC.

I made active both external Thermocouple Ports on the board which will give us the opportunity to explore fully different re-flow temperatures  and solder compounds. 

I will post my results with the new code as soon as I have completed the job.

I looked at the the 5" Touch screen update but I don't quite fancy carving a slot in the top cover, besides I'm delighted with what I have now, which apart from this one minor bug, works perfectly. 

Finally, I'm still having issues  with the Fan. Finding a suitable 230v replacement Fan that runs slowly  instead of just growling is a bit like looking for Unicorn Manure.

  Are you sure? yes | no

PhillyFlyers wrote 08/02/2019 at 21:16 point

yeah, I haven't done anything with that USB port yet.. maybe if I get something setup with this new board I can port it to the pic32 version.


Yeah, even with my fan, the min speed is about 80, anything lower and it's not even voltage to keep it moving...

I would think with 230V you should be able to find a decent lightweight fan that could run at min speed of may 50-60 on the setting... but definitely need to find a plastic type, the metal ones are just too heavy and take too much voltage to get it moving..


what's your min speed where it actually spins and doesn't grind?

  Are you sure? yes | no

KeithF-git wrote 08/02/2019 at 12:55 point

Thank You for your replies. Yes I'm over the moon with the upgrade, as I said previously, a bit of a challenge, but hell man us Geordies don't give in until the very last drop is squeezed from the lemon.

I had thought it was something in the coding, but after taking a quick squint at it realizing it is well above my pay grade to be able to sort it out.  Looking forward to the receiving the update. 

Once again Thanks for a superb project.

  Are you sure? yes | no

PhillyFlyers wrote 08/02/2019 at 19:11 point

Alright, it's fixed, give it a whirl and make sure everything works! 

it was a fun project to do, definitely had fun doing it, especially once I could use it and get some nice reflow runs in..


If you ever get really adventurous, you should check out my STM32 flavor of this, but you do have to cut a small slot in your oven case for the TFT touch screen for this version, but it's light years better than the little lcd screen... but it's certainly not an easy board to assemble... 


with the TFT version, you can go 5" or 7" touch screen, there is NO more keyboard or buttons, it's all touch driven, and an 800x480 color display, graphics are sweet.

  Are you sure? yes | no

KeithF-git wrote 08/01/2019 at 16:30 point

Has anyone had this problem. I have programmed Custom 1 profile and all is working well. Today I tried to set up another profile on Custom 2 for a new Alloy Paste but when I hit F3 to edit and create the profile on Custom 2  it jumps back to Custom 1 and tries to edit Custom 1.

It will not let me create another custom profile  which is bloodywell annoying.

I'm not sure what is making it do that. Any help or advise would be really appreciated.

  Are you sure? yes | no

PhillyFlyers wrote 08/02/2019 at 11:55 point

Hi Keith,

Wow, cool to see someone actually made this board :)   I haven't touched this project in quite some time now, I'm working on the newer version I took on, the STM32H7 version, using a touch TFT.

I'm guessing this is a bug of some sort, it's been so long since I worked on this code.  I'll play with it this weekend, I'm sure I made some stupid bug there..

  Are you sure? yes | no

PhillyFlyers wrote 08/02/2019 at 12:19 point

** update **

Hi keith, 

I see it already, the original UnifiedEngineering code that I started from for this version, had only ONE custom profile, whereas mine has 10.  There was some hard coding of the 'edit' function, where they always set to the first custom profile (since there was only 1)

I'll fix this and test out tonight, and update the repo and released binary.... thanks for finding this bug!

  Are you sure? yes | no

KeithF-git wrote 07/24/2019 at 20:47 point

Good evening all and thank you so much for sharing this project. It is an absolutely fantastic piece of work and has proven to be quite a mammoth challenge, and one which I am proud to have completed. 

In contradiction to Elasia it does fit the smaller T962 but you need to make a backplane to mount it onto the casement studs. Very many thanks to Ryan for pointing out the absence of a decent Earthing ground stinging the Fan MOSFETS out.  I must confess I had almost given up and created a workaround by stripping the VOM Opticoupler out and wiring the signal  onto another SSR.  It did work, but very crudely.

For the life of me I couldn't fathom out what was ailing the project, so I'm really grateful to Ryan, (et al) for putting me onto the earth bond problem.

I have one other problem. Over here we have proper AC at 230v potential and the problem I'm having is replacing the Fan, obviously I cannot use the recommended Fan which is rated at 120v AC.  I have tried 3 out so far but non are giving me a slow gentle 'blow' at low speeds.  Has anyone in either the UK or Europe (which is all 220v AC ) found a suitable Fan or can recommend a Fan suitable for the job.

Finally if there is anyone out there wanting to know how I mounted the PCB into the T962 or is doubtful of taking on the task, I'll help out as best I can. I also have a number of PCB's I can let go for what they cost me, the folk who make our PCB's have a minimum order quantity.      

  Are you sure? yes | no

Elasia Squishie wrote 01/09/2019 at 21:07 point

You might remove T962 off the listing for this.. the board doesnt fit lol.. opps

For anyone interested in a baby version of this, i'll be spinning off a smaller board of this lovely design for the smaller T962 oven.. not sure when.. maybe Feb i'll release something complete

shameless plug if anyone goes looking

https://hackaday.io/project/163248-t962-controller-drop-in

  Are you sure? yes | no

Ryan wrote 12/17/2018 at 05:05 point

Notes for anyone building this. Make sure that the board itself is grounded or tie neutral to GND. If you do it like me and reuse the insulating washers and paper you will have an oven that eats FET's for lunch. :) 

If GND floats than the FL5160's ZC pin biases the entire digital section and fails to accurately sense the zero-crossing, causing the dimmer to chop voltage at the AC peak and the inductive spike blasts the 2nd output FET into oblivion.

  Are you sure? yes | no

Elasia Squishie wrote 12/30/2018 at 20:09 point

Thanks for the tip, I just ordered all the parts for this since i have a T962.. just happened to also be a PIC engineer for the last decade so excited to see this project here using one since i have all the gear already for it

Also for anyone looking to do this, I've been using jlcpcb.com for my project boards, this one they gave me 5 with a stencil for 44 bucks with shipping.. they take 1-2 days to produce then ship out.  Some half the cost of osh, just beware they dont do a lot of engineering checks on you either like you will find elsewhere so might not be the best place if you are new to pcb design and sending custom work out

  Are you sure? yes | no

PhillyFlyers wrote 02/21/2019 at 14:01 point

Thanks, yeah, I posted an update to the description that you should NOT be using those felt insulators, the OEM board was 'floating', because of how they setup that triac circuit.

This board was setup so it could be properly grounded to the oven chassis, of course assuming you fix your oven's grounding issues and scrape that paint so the GND terminal they installed actually connects to GND  :)

Yeah, you can have funny potentials between AC and board GND if everything ends up floating.

  Are you sure? yes | no

Nicolas Chaslot wrote 10/16/2018 at 09:58 point

Hi :)

Did you get some time to work on the upgrades? :)

  Are you sure? yes | no

PhillyFlyers wrote 10/16/2018 at 11:07 point

Hi,

I started on the new version, using the STM32... I'm getting ready to start testing the pcb soon, then work on the software..

https://hackaday.io/project/161716-t962a-controller-with-5-touch-tft-using-stm32

for 'upgrades' are you referring to the changes to the FL5160 powering?  I did make the schematic and board changes for this pic32 design, to power the 5160 from the AC as I mentioned... but I haven't posted it yet since I haven't tested it to make sure it really does work ok that way..

I'm using that same chip in my STM32 layout, as I really do like this setup, and it works great, so I'll be testing it real soon with the STM32 board, so at that point I can verify if it does work as the datasheet says it should

(yeah, I don't always trust datasheets for their word :)   )

  Are you sure? yes | no

Nicolas Chaslot wrote 10/22/2018 at 08:06 point

Awesome, i joined the other page then to follow the progress as I'll probably jump directly to the stm version!

Can't wait to see how that goes!


  Are you sure? yes | no

Nicolas Chaslot wrote 09/13/2018 at 06:30 point

*Replying here again as there seems to be no way to add more than two comments *

I was wondering though, at that point, isn't it simpler to just consider the controleo 3 interface maybe? It does have everything needed and we don't really need anything custom if we ditch the original screen anyway..

I'll follow your work anyway, can't wait to see what you'll come up with

  Are you sure? yes | no

PhillyFlyers wrote 09/13/2018 at 10:49 point

Yeah, this site is funny with the limits on comments... but no worries, I can follow you guys wherever you end up posting in here...

I saw that ControlLeo before... it's not bad, certainly a quick solution if you are just looking to get your oven up and running with something better? 

You'll have to of course do some mods, like add an SSR to the AC fan, which of course puts it back to just being 'full on/full off', etc... same with IR elements, since that board is giving you I/O outs for driving relays or SSRs, etc..  unless you can PWM to those I/O pins, not sure how that board was setup and to which I/O pins those are tied to?  

I see it only has one TC connection, (you can add more with another board), but again you lose one of the T962 TCs if you just go with the stock setup... so hmm... I have quite good results in my setup now, which is using 4 TCs, the two 962A stock ones, and I added another 2 that I tape to the target board...

But this is as much about the challenge and learning new concepts when I do these projects...I'm also not really a fan of arduinos when doing something like this, I'd rather make a more powerful design from scratch.   So yeah, can seem like doing something that's already mostly covered in the Leo design, but again, I enjoy the fun of the entire thing from concept to design/debug...

  Are you sure? yes | no

Nicolas Chaslot wrote 09/13/2018 at 10:55 point

Sure, I see your point there :)

Keep us updated anyway, I'm in for beta testing of the new version! In the mean time I'll just replace the tape on the oven and try it "stock" for fun

  Are you sure? yes | no

PhillyFlyers wrote 09/07/2018 at 15:56 point

** Another interesting thing I just noticed about the FL5160/FL5150, that 'Vdd' pin (5v) appears it's actually an OUTPUT, not a supply pin.  So you can use that 5v output to set the dimmode to hi or low.  

The datasheet for this part is not the best, as to me it seemed initially the Vdd was a 5v input supply rail, not an output.  But they say in some of the text (and you can see in the logic diagram), this Vdd pin produces 5v from an internal regulator.

So, I'm going to test out supplying Vs to this chip from the 120VAC source, and removing the Vdd connection to 5v altogether, and just connecting it to DimMode.

**

  Are you sure? yes | no

Nicolas Chaslot wrote 09/10/2018 at 16:46 point

*replying here as i can't reply to the other post..*

An update with a stm32 could be awesome! We could just use the original screen hole to pass cables to the outside and have a machined part screwed from the inside to cover the hole and hold the new screen :)
That would be cool i think!

Anyway keep us updated, i'll wait a little before i order the boards and parts then ;)

  Are you sure? yes | no

PhillyFlyers wrote 09/12/2018 at 21:34 point

Yeah, probably a good idea.. I'm putting together the schematic now for an STM32 based board, will start with a 5" TFT-Touch.  (you can find many panels that use the same interface setup, so would be quite easy to go much bigger if desired!)

Hardest part will be getting the graphics, menus, etc figured out with a real LCD panel... but STM has plenty of code already, so I'm not starting from scratch :)


Once I get my board layed out and back from Osh, I'll start a new project on here with the starting details...

  Are you sure? yes | no

PhillyFlyers wrote 09/06/2018 at 12:01 point

*** All,  I'm intermittently seeing some brownouts/low voltage with the FL5160, when running full bore, ie heaters fully on, and fan attempting to run **..

when the FL5160 sees a low threshold voltage on it's VS pin (somewhere in the range of 10v or lower), it will shut itself down, and no longer control the AC fan.  What I'm seeing is that the 9VAC transformer they have is dropping too low, prob. due to the AC voltage dropping a bit under the full load.

In my area in the US, the output from this transformer is usually around 11-11.5VAC, as I'm guessing our 120VAC here is prob. slightly above the VAC that this transformer was originally designed around, hence the 11-12VAC output instead of the 9VAC it is spec'd for.

I ended up just recently ordering a simple 12VAC 500ma Transformer from amazon for like $12, was a drop in replacement, and fixed my issues. 

*Although*, this cheap china-made transformer is actually spitting out almost 17VAC, not 12!  So I had to mod my board to drop a resistor inline to VS to not blow over that 17V limit.. 

(as I found out when I blew the top off a couple 5160s :)   )

The better approach to this problem, would probably be to follow that FL5160/5150 datasheet, and power VS right from the AC mains, only requires a couple components, but at the time I didn't think it was needed, as the 9VAC input was fine.  But now that I'm seeing these issues, this may have to be re-visited.

  Are you sure? yes | no

Sachin Gowda wrote 09/10/2018 at 17:00 point

Hi,

I tried to power the Fl5150 from the AC mains directly using the given application circuit. Its 220v AC here. I connected the 35k resistor as specified in the datasheet but, it blew up. It was a 1/4th watt resistor. I'll check it with higher watt resistor and will let you know. But I think there will be a lot of power wastage in this method.

  Are you sure? yes | no

Nicolas Chaslot wrote 09/05/2018 at 06:50 point

Hi,

I just ordered my first T962 oven and i'm really interrested in your board. However, i was wondering if it would work on the 240V version of the oven?

Thank you very much,

Nick

  Are you sure? yes | no

PhillyFlyers wrote 09/06/2018 at 11:53 point

Hi,

As far as I know, this should work fine, assuming their 9VAC transformer is still essentially the same, just setup for 240VAC to 9VAC or so?  

Also, is your 240V @60Hz or @50Hz?  if @50Hz, you'll need to use the FL5150 instead of 5160...

** please see my general comments above, as I'm encountering some intermittent issues with the 9VAC transformer it comes with, and the FL5160 chip **

  Are you sure? yes | no

Nicolas Chaslot wrote 09/06/2018 at 12:40 point

Honestly i didn't even knew there was a transformer haha. But seing your other comment, i could as well ditch that and buy a standard 12V wall power supply and mount it in the oven somewhere... Although maybe being at 240 instead of 120 the voltage drop on the main line should be less noticeable...

Do you think you will modify your board to take the ps from the main sometime?

  Are you sure? yes | no

PhillyFlyers wrote 09/06/2018 at 13:35 point

Yeah, I'm going to test out the method mentioned in the datasheet, and see how it goes, if it turns out to be reliable, I'll make an update to the schematic and board, and update this project...

I've also been tossing around the idea of doing an entirely new design again, using maybe an STM32, this thing would really be awesome if we could have a nice color touch screen.

But going that route will most likely require having to mod the case in order to fit a larger touch screen, or alternatively having a screen sitting externally somehow, not mounted inside.. so I'm looking into it...

  Are you sure? yes | no

Sachin Gowda wrote 09/04/2018 at 11:05 point

I am having difficulty understanding how FL5160 works. How does the Zero Cross Monitor work? I replicated just the FL5160 part of the schematic but cannot get it running. I am providing the DIM_CONTROL voltage via an arduino PWM passed through an RC low pass filter. Can we connect the VS pin to 5V directly? From the datasheet I see that the voltage at VS is used to drive the gate. I want to use this IC to drive a MOC3021 and hence a TRIAC. Is it possible? Could you please help me. Thanks!!

  Are you sure? yes | no

PhillyFlyers wrote 09/06/2018 at 11:51 point

Hi There, 

sorry for the late response... So this FL5160 is kind of annoying in that respect, it's a great chip otherwise, but the VS requirements is annoying.  It has a 'brownout' voltage minimum, which is around 9.5v or so (it's in the datasheet)...

So you need to power VS with at least 10V minimum, I'd recommend more like 11-12v (just don't go past 17V, as it's shunted at 17v, and anything over will cause nice chip blow outs :)  )

Also, you can take a different route and power the VS right from the 120VAC in, as they show how to do in the datasheet, it's just more circuitry, I decided to just use the 9VAC input they already gave us from that small transformer to power VS.  (the AC output from this transformer is closer to 10-11VAC, prob. because our AC ranges in the US are a bit higher than the transformer windings were set at)

** please see my general comments above, as I'm encountering some intermittent issues with the 9VAC transformer it comes with, and the FL5160 chip **

  Are you sure? yes | no

Sachin Gowda wrote 09/08/2018 at 11:53 point

Thank you for your response! I totally skipped the brownout voltage. Thanks for mentioning it. Also could you please help me understand how the zero cross monitor works in this IC?

  Are you sure? yes | no

PhillyFlyers wrote 09/08/2018 at 21:08 point

Hi,

The zero cross detection on this chip works from the AC voltage that is fed to the 'ZC Monitor' pin through the 1MOhm resistor.  It only takes a small bit of the AC voltage waveform for the chip to be able to detect where the AC waveform crosses 0.  You can use either the neutral line or the hot line to feed the ZC Mon pin.  (I chose to use the hot, but according to the datasheet it can work with either.

The 'Dim Control' pin is for the analog input, coming from the DAC, based on a 2.5V reference voltage.  This input voltage is what tells the chip at what 'delay' (from the zero-cross point) to fire the mosfets on.  It has it's own internal oscillator/timing, based off of 60hz (or 50hz if you use the FL5150), so that it knows when to fire the fets on and then off, based on your set input voltage.

So basically using this method, you are turning on a certain percentage of each AC pulse, from 0 to full, giving you a smooth AC waveform to the load.  When using a triac, you are instead turning on and off 'chunks' of the AC waveform, but not portions of each wave, instead just periods of time of the wave that are just being turned off, so you end up with a very jittery and noisy motor. That's why the default oven sounds like that when not a full speed, it makes grinding and strange noises.

You could indeed just use the microcontroller to do the AC zero cross detection, you could feed the same small AC voltage from that 1M ohm resistor (or similar) to an I/O pin, and sync with the 60hz cycle, and do the fet control yourself.  But that's more overhead the mictrocontroller has to take care off, and another timer it has to be constantly responding to.

I chose the 5160 to just offload all of this.  But certainly a very viable option if you want to make your own setup, it wouldn't be hard to all to implement into the micro or arduino core or whatever you want!  I've encountered online examples of people that have done it,it's fairly simple, just takes some coding to get the sync and all that right.

  Are you sure? yes | no

Sachin Gowda wrote 09/10/2018 at 16:52 point

Thanks a ton for the information!!

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PhillyFlyers wrote 04/05/2018 at 20:25 point

** FYI: Updated the OshPark board to have tented vias, and added silkscreen borders for SMD component placement

**

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David B. Bitton wrote 02/12/2018 at 19:04 point

I'm looking to use the same PIC32MZ MCU in my own project. Are you using any coding frameworks such as Harmony? I looked at the src and it doesn't look like Harmony (or Arduino for chipKit boards). Since you said that the PIC32MZ is a drop-in, what is it replacing? Thanks!

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PhillyFlyers wrote 02/12/2018 at 23:51 point

Hi,

Nice, this is my 2nd project using the PIC32MZ, I'm really liking this micro.  I did both projects just using the MPLABX IDE, just writing everything in straight C.  I checked out HARMONY, but I prefer to code right at the bit level.  Harmony basically is a higher-level 'wrapper' for coding for the hardware.

But it's certainly a nice way to go if you don't like flipping all the bits and registers.  

The MPLABX IDE I'm enjoying using for the dev, they use NETBEANS for the GUI part of the tool, so you can customize it with all sorts of netbeans themes.  I like the 'DARKULA' them, as it is almost identical to the DARK THEM that MS visual studio has (which I also do much of my development on for non-embedded projects).

I do highly recommend you pick up their debugger, ICD3 (or even the new ICD4 if you wanna pay the extra for it)...their pickit3 is hardly a debugger, it only does hardware breakpoints, it's really only good for programming.  The ICD3 you can do everything with, all through the MPLABX.

There is some minor errata with this micro, they've fixed a good bit of them now, but just make sure to check out the errata sheet... but I had zero issues with any hardware bugs.


(The original board uses an LPC2134 micro, it's ARM based, not bad, but it doesn't run that fast, and it's peripheral setup is kinda dorky).

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David B. Bitton wrote 02/13/2018 at 03:04 point

It's tough coming from C# in VS to MPLAB, but such is life; still better than VB6. I'm using their dev board which has the debugger onboard. I'm still kicking the tires.

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PhillyFlyers wrote 02/08/2018 at 00:41 point

I decided to design an entirely new controller, as the original board that comes with this oven is quite bad.  The op-amp setup for the TCs is really cheaply done, as well as the rest of the hardware around the cpu.  Also, the TRIAC design for attempting to control the AC COOLING FAN is done very poorly.

Trying to control an AC fan speed with 'proportional voltage control' leads to noisy/jerky motions of the fan, and on top of that no real speed control.  To really speed control an AC fan, a phase-cut control circuit needs to be done to correctly turn on/off a proportional amount of 'each' AC phase cycle, which is what the FL5160 (5150 for 50hz regions) phase cut controller accomplishes with the two N-Mosfets.

I know this is not an easy circuit for any novice hobbyist, the entire board uses surface mount components, you really need at least a decent small tip soldering iron, and some type of bench magnifier for the small components.

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