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Breaktru Forum  |  eCigarette Forum  |  Modding  |  Topic: It's Alive
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Author Topic: It's Alive  (Read 43616 times)

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Offline synchro

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Re: It's Alive
« Reply #50 on: August 22, 2012, 10:57:30 PM »
Very cool, SPI is interesting in that its not formalized like I2C so the Arduino has its own implementation, PIC has its own etc. Definite speed advantage tho.

Are you having the boards built out or are you soldering components yourself?

Offline CraigHB

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Re: It's Alive
« Reply #51 on: August 23, 2012, 01:00:36 PM »
The boards are sent out for fabrication.  I can make simple boards myself and I often do for prototyping SMD on breadboards.  However, for actual finished projects, I always have my boards fabbed.  It's worth the expense in my opinion.  You can find shops that will do them cheap enough.

I2C is a more advanced bus architecture, but the main reason I use SPI is actually because of the MCU I'm using.  The I2C module is not included in the MCU's peripheral pin selection feature.  That's a really nice feature because it allows you to assign functions to pins.  That makes circuit board design easier.  It's a hassle to code the pin functions, but it's a lot more hassle to arrange circuit traces in sometimes odd configurations.  Also, SPI tends to be the default bus architecture for many components.  I can get the same digital pot with an  I2C interface, but the LCD I'm using is only available with SPI.

Offline asdaq

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Re: It's Alive
« Reply #52 on: September 04, 2012, 04:25:00 PM »
Craig, the circuit, the case and the connector, wow. You make me feel like a caveman whose eyes have been opened to a number of possibilities I really hadn't thought about.  Excellent work, and long time no see.  :)

Best of luck on the smaller versions too!

Offline CraigHB

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Re: It's Alive
« Reply #53 on: September 04, 2012, 04:42:27 PM »
Thanks asdaq, nice to see you as well.

I'm excited about the smaller one, should have PCBs today, enclosures are in the mail, and LiPo cells should be here end of the month.  I'll post some pics here when I finish it.  Finally ordered a camera so I'll actually be able to take photos.  My camera died like a year ago and it took me that long to order another one.  That's why I posted a video using my PC camera.

Boxes are much more flexible than tubes as far as having room for electronics.  Boxes are all I've been doing.  This latest one will finally be small enough to compete in size with a tube mod.  It was quite a challenge to pack all the electronics onto such a small PCB.  It's still a box, but it will be pretty short, only 81mm with the same width and breadth.  It will have 1400mAh instead of 2200mAh, all other features the same.

Offline asdaq

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Re: It's Alive
« Reply #54 on: September 04, 2012, 05:36:51 PM »
I just saw this thread today, so it was nice to read all at once. If you need help financing the camera, please count me in. ;)

Offline Str8v8ping

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Re: It's Alive
« Reply #55 on: September 10, 2012, 06:16:09 PM »
Awesome work Craig . I dont think it can get much better then this.

Offline CraigHB

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Re: It's Alive
« Reply #56 on: September 11, 2012, 07:22:29 AM »
Thanks.

Got circuit boards last week and I'm working on the smaller one now.  Running into some issues with the electronics.  The higher impedance of the smaller cell and the use of a smaller inductor with higher DCR is giving me trouble.  At maximal outputs, I'm getting a lot more heating and the booster's NMOS switch is getting too hot.  It drives up RDS(on) which causes the controller to hit the hard-wired "on" voltage limit across the NMOS drain-source.

After some long and tedious searching, I found a Vishay MOSFET with lower on resistance and low enough gate charge.  Hoping that will solve the problem, parts here later in the week.

Another issue I'm having is that the smaller board and lower heat dissipation is tripping the parallel PTC fuses I'm using.  You can trip any PTC fuse by getting it hot enough regardless of current flow.  They're on the same pad as the input PMOS and it generates a good amount of heat at maximal outputs.  I've decided to forgo the use of them in lieu of a temperature sensor on the booster's drain pad.

I've used all my pins on the MCU so I had to use one of the programming pins with a jumper for the temp sensor.  I don't like it since I'm now relying 100% on the MCU for safety features and I always like to avoid jumping programming pins, but I don't see any other way around the problem.  To keep input impedance down, I'd need bigger fuses and I just don't have room for them.  This board is tiny and I keep adding stuff as it is.

I was expecting this build to go quick, but it's turning into a whole new project now.  I feel like I keep digging myself deeper with this one.  I could just say screw it and limit output current to 4 Amps, but I want my 30 Watts dammit.  It's a bitch because at that output, the power consumption for any impedance is a factor of approximately 100 (I2R).  Though, it's a design challenge and I'm up for it.

Offline sterling101

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Re: It's Alive
« Reply #57 on: September 11, 2012, 05:46:16 PM »
If anyone can do it you can Craig!

I'm struggling with the new MCU now I've started setting up in the final config.  Can't seem to stop it resetting so might have to re-do the code from scratch bit by bit until it works.
Certainly a challenge but like you say - I'm up for it too :)

Offline CraigHB

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Re: It's Alive
« Reply #58 on: September 11, 2012, 07:58:30 PM »
Hehe, thanks for the vote of confidence.

Unless you've programmed a reset into your code and it's getting called arbitrarily, spurious resets are usually indicative of an electrical noise problem.  It can be a real headache.  The higher the currents the greater the magnitude of noise.  I have a pretty far out ground plane on my PCB to avoid that sort of thing.  Under the booster it covers 3 layers and is isolated from the MCU plane.

Offline sterling101

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Re: It's Alive
« Reply #59 on: September 11, 2012, 08:35:54 PM »
The setup is the same as the old chip besides the internal oscillator but I've got an idea it could be one of the fuse settings doing it as it flickers the screen a lot then resets fully so maybe something to do with the WDT or brownout fuses.
Just need to build the code up bit by bit until it falls over to be 100% sure though as it could be something to do with the portb interrupt handler too using the new generation of MCU with enhanced CCP it seems to tie into the interrupt handler different to the older one.
Will post some info on my thread once I've narrowed it down a touch more so as not to hijack yours too much :)

Offline CraigHB

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Re: It's Alive
« Reply #60 on: September 12, 2012, 01:06:44 AM »
Some code failures can cause spurious resets so that may be the issue.  For example, if a stack overflow occurs, the program counter may keep incrementing, loading each NOP in unprogrammed memory space until it rolls over to zero where the MCU's reset instruction lives.  Though it usually takes something pretty obvious for that to happen just from a programming error.  One of the many things that are nice about the 16 bit PICs compared to the 8 bit PICs is the stack is pretty bulletproof.  If there's a problem like that in my code, it gets trapped by an ISR that displays an error.


« Last Edit: September 12, 2012, 01:13:22 AM by CraigHB »

Offline sterling101

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Re: It's Alive
« Reply #61 on: September 12, 2012, 03:42:49 AM »
Found it, fixed it, vaped it :)  Floating pin messing up everything - so easy to miss when the code to hold it high has changed between MCU's!
Quick re-read of the data sheet followed by some face palming and it's now holding stable.

Next stop, tweaking the PCB a bit as I've had to move some pin assignments around to suit using the ECCP module correctly as it's pin re-assignments aren't quite what I was expecting so buttons and atty have had to be mixed up a touch....

Offline t-minik

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Re: It's Alive
« Reply #62 on: January 03, 2014, 06:52:45 PM »
WOW !  freaked_out:

sorry it this one is my 1st post but :


awesome job Craig !

any chance to get some schematics pcb and firmware untill it's stable ?
I really would like to try to build one

Offline CraigHB

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Re: It's Alive
« Reply #63 on: January 03, 2014, 08:07:08 PM »
Thanks,

I'm actually on to a new design that is  much nicer in terms of electronics, higher output, wider voltage range.  I'll post some preliminaries on that one once I get the first board up and running, actually getting pretty close to submitting the PCB to the fabricator just about now.

I'm not really willing to to publish any of my designs in an open software/hardware sense, but if you're serious about building something similar, I'd be happy to offer any advice I can lend.

Offline t-minik

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Re: It's Alive
« Reply #64 on: January 04, 2014, 05:51:47 AM »
Hi Craig.

Thanks for your reply.

Unfortunately I'll never be competent in software development, I triedmany times but it remains totally dark in my brain.
I'm not so bad to make a guitar fx but that's all, microcontrollers are another world to me.
Hope we get one day an open hard/soft ecigarette project.

Offline CraigHB

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Re: It's Alive
« Reply #65 on: January 04, 2014, 04:49:28 PM »
I saw someone tried to start an MCU based mod in an open source manner on ECF.  I haven't visited that forum in quite some time so I don't know what ever became of it.

One of the big problems with microcontroller stuff and open source is it's highly dependant on hardware.  Unlike computer software that is limited to a handful of processor platforms using standard interface protocols, there's a truly vast array of microcontroller platforms each with its own set of software requirements.  Microcontroller platforms just don't cross over much.

So, anything open source would have to be both a hardware and software project.  Even small changes in hardware can require rather large changes in software.  That's the goal of Arduino, to eliminate that hardware dependance, but they really have not made much progress in that area.  The majority of Arduino stuff is still pretty hardware dependant.


« Last Edit: January 04, 2014, 05:09:10 PM by CraigHB »

Offline Thurge

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Re: It's Alive
« Reply #66 on: January 22, 2014, 01:51:40 PM »
Hi Craig,

If someone were willing to try to learn how to build a similar device where should they start? I'm decent with a soldering iron and I can read a schematic (might need some reference at hand for symbols i don't remember) I'm not afraid to learn how to code (I've done some light coding in the past and understand how object oriented languages work etc) I just don't know enough about the which component and why part...

Offline CraigHB

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Re: It's Alive
« Reply #67 on: January 22, 2014, 03:07:52 PM »
Hi Thurge,

There's a few of us here playing with mods that incorporate an MCU.  There's a number of platforms to choose from.  Most commonly, you can incorporate an Arduino based system, but you're not limited to that.  Arduino is nice because it provides an easy to use and free (that's the big one) way to program MCUs to your requirements.  Arduino does have some limitations so you may want to look at other options there as well.

You do need to program your MCUs typcially using the C programming language, but you can use assembly for platforms other than Arduino.  I like assembly a lot because it's down at the machine level, but it has the big disadvantage of being tedious and repetetive.  Depending on your experience with programming in general, it may or may not be a big task to become familiar with MCU programming.

In terms of circuit design, well, that's the hard part.  There's lots of issues you can run into in building your own circuits and it's where you'll find yourself spending the majority of development time second to programming.  That is, solving electrical problems.  There's just no shortcuts for that other than experience and study.  You just have to roll up your sleeves and do it.  I still learn things every time I do a new project and I've been doing stuff with electronics for decades.  Depending on your knowledge level, you may want to start with the tutorials at http://forum.allaboutcircuits.com

The soldering is not the hard part IMO.  The trick there is mainly the right tools and equipment.  Soldering itself is really not very hard.  There's some great tutorials on the net about soldering electronics that will get you going pretty quick there.  I would suggest the ones at EEVBlog; http://www.eevblog.com/episodes   See episodes #180, 183, 186, 434, 415.

Making your own PCBs is not terribly hard, but it takes some time to get things sorted out so you get good prints.  The best way I've found is the "toner transfer method".  Having them fabricated is a good option and I would suggest OshPark for that.  In some cases you may want to make them yourself and in some cases you may want to have them fabricated.  http://oshpark.com is a co-op that makes it quite inexpensive to have them fabbed.

Well, hopefully that covers it.

Offline Thurge

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Re: It's Alive
« Reply #68 on: January 23, 2014, 01:11:40 PM »
Earlier in this thread (I think...) you mentioned the max1709 as being an easy chip to use. I found the max688 which supports higher output current and higher output wattage (in excess of 20 Watts.) It also has less pins which I would assume means it's more difficult to setup (less pins means you need additional external modules to control it) would that be the case?

Offline CraigHB

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Re: It's Alive
« Reply #69 on: January 23, 2014, 02:58:19 PM »
Let me take a quick look at it, need to go to the Maxim site, I go there a lot.  I like their stuff since they always seem to have those osbcure things you might need, but their stuff is always expensive so I only use them when I can't find something cheaper.

Hmm, that part number is no good, comes up with an LDO regulator that has been discontinued.

In any case the MAX1709 is an easy one to use and it can do the job pretty well, but if you can find something with better specs, go for it.  The boost or buck-boost controllers are not nearly as common as the buck controllers so options are a lot more limited.

Offline Thurge

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Re: It's Alive
« Reply #70 on: January 24, 2014, 02:54:04 PM »
What about a fixed voltage circuit? I mean something that always gives you 4 volts until your battery gets too low and can handle high enough currents to support sub ohm setups? Has this been done before?

Offline CraigHB

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Re: It's Alive
« Reply #71 on: January 24, 2014, 03:51:08 PM »
You could do that with a step-down converter quite simply.  Things get a lot easier when you use series cells, but the issue that comes with that is charging if you want to use a non-removable battery.  Even then, only if you want to use a USB charger specifically. 

The way you do things is highly dependant on what you want.  Once you define your requirements in specific manner, then you can think about how to do things in a specific way. 

A mod that can put out a lot of power is easy to design.  It's when you start adding features that things get more complicated.  Define your feature set first, then think about design.  If you want a mod that only needs to put out 4V at a high power level, the design is almost trivial.  If you want to start adding gauges, controls, and other features then you get into something more complicated.

Offline whoi

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Re: It's Alive
« Reply #72 on: February 25, 2014, 09:09:42 AM »
This is awesome. I want to step into microcontroller based mod, just not sure if I have the patience lol

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