[foodhackingbase] [incubator] Fwd: Re: incubator push

[Frantisek Algoldor Apfelbeck]

Hi to all,
my answers to both Robins and especially Arnd's posts are in the text as 
### I hope it will help to move us forward.

On 2014-09-02 17:30, Scheibler Robin wrote:
> Dear All,
> 
> I have not been following very closely the thread. I have been however
> working on a design that seems orthogonal to yours, but might provide
> inspiration, so I’d like to share it.
> 
> My design violates many of the requirements that you set. However, it
> should be very cheap, i.e. <5$ for the controller board, including a
> relay. It relies on the ATtiny85, uses a thermistor for temperature
> sensing, and an onboard mechanical relay (at the moment). My idea is
> the same as my previous design, that is it uses a regular light bulb
> as a heat source (no cooling). One can just scavenge a nightstand
> light and a styrofoam box to produce a makeshift incubator.

### Sounds as nice set up for testing the software and having a fine 
heating option, which is most of the time what you need. I remember 
fighting with calibration of thermistor in the past a bit and personally 
I do not have experience with ATtiny85, so I will have to pass on this 
one.

> It doesn’t have any display, only two LEDs. In the next version, I
> intend to put these two LEDs on the 2-wire pins, so that there is a
> possible extension with LCD i2c screen. In the same spirit, a
> potentiometer allows to choose between a few preset temperatures
> (37.5, 40, 45, etc). The board is reprogrammable through ISP.

### That souns clever to me :-) Cheap and efficient.

> Anyway, here’s the github repo. Note that the code is still alpha and 
> buggy.
> https://github.com/BioDesignRealWorld/IncubaLibre
> 
> Cheers,
> Robin

#### Give me few days and I will add a cathegory to our wiki which would 
mention similar projects to our one, I will add the link to your project 
there - could you send me the link to the article which went out about 
your incubator, I am not sure where I have it, thanks!

> On 2 sept. 2014, at 07:49, Frantisek Algoldor Apfelbeck
> <algoldor at foodhackingbase.org> wrote:
> 
>> Hi to all,
>> I'm forwarding Arnd's email about the experimental incubator to the 
>> list and to the people who were recently actively involved with the 
>> experimental incubator project. Please read through that and comment 
>> so we can prepare good proposal for the upcoming Crowdsourcing 
>> Campaign.
>> 
>> Many thanks!
>> 
>> Sincerely from Jeju,
>> 
>> FAA
>> 

>> Hi guys (is Lars still involved? could you forward this to him and
>> others who might be interested ?)
>> 
>> Sorry for the delay in replying/designing.
>> 
>> Basically; i get swamped with projects and things to take care of;
>> which lets me not focus on the things I need to finish.
>> 
>> Before my vacation, I was about to get into contact with Marcel and
>> visit him to see his implementation of driving the peltiers and
>> perhaps to philosophize about how to do a PCB version.
>> 
>> 
>> There are a number of things that are 'a problem' and are in conflict
>> with eachother, in any given design.
>> 
>> In our project, there are a few things that are wanted, but not all
>> can be satisfied. Here is a list:
>> 
>> 1 Should not be too expensive
>> 2 Should be easy for everyone to get the parts they need (local or
>> internet)
>> 3 Should be easy to build
>> 4 Should be safe to build
>> 5 Should be safe to use
>> 6 Should be easy to change software
>> 7 Should have space left for options/extras
>> 
>> I numbered the list so I could walk through the considerations with
>> what we went for and why we did so and what I would like for the 'new
>> version'.
>> Please find my 'conclusion' at the end for a view of what I am working
>> on. Please let me know if you think this is the right way to go.
>> 
>> 1 Not too expensive
>> If you are going to have a CPU-based design, it is good to choose
>> something abundantly available and well-known.
>> 
>> Arduino's are already 'expensive', in a way, but they are still at the
>> bottom of the market when it comes to 'bang-for-buck' ratio;
>> especially the clones and 'micro' or 'nano' versions that you can get
>> on Ebay for less than $3. Great value, ties in well with point 6: easy
>> to write software for.
>> 
>> http://www.ebay.com/itm/200957063666

### We have talked about that before, the Arduino micro version sounds 
feasible as you suggested and exmplained to me before.

>> The interface will need some kind of feedback. There are multiple ways
>> of dealing with this. Either offload the entire interface to some
>> 'smart device', connected via bluetooth/wifi/etc , or provide a simple
>> local UI via LCD + buttons (or touchscreen).

### I'm definitely for local interface as a basic option.

>> Since it is good to *always* have a local screen on the device; making
>> sure that this is present is a good choice. Bluetooth/etc can be
>> provided as option (point 7).

### Based on the previous use of the 2.1 mamut experimental incubator, 
the screen and buttons were working fine, would love to keep to similar 
set up (maybe bit better responding buttons if I can suggest).

>> For this purpose, a character LCD + buttons works; but it costs a lot
>> of pins. (6 or so for LCD, at least 1 for all buttons together),
>> conflicting with Point 7
>> 
>> Another option would be to find a popular phone LCD (Nokia 3310?) +
>> joystick assembly that is cheap and available everywhere....
>> Personally, I have the feeling that 8x16LCD + buttons is really just
>> 'the safest option'...
>> Saving pins can be achieved, however, using one of the many I2C->LCD
>> convertors on the market today.
>> They are quite cheap and require only 2 wires on the I2C bus..
>> It also makes it easier to make a design that has the LCD somewhere on
>> the front of a box, while leaving the rest of the PCB somewhere else.

### Saving pins is very important. Do I undestand correctly that the LCD 
display would need two pins (if using I2C) and another one (or more) for 
the buttons?

>> Ebay sells them for $1.05 including shipping
>> 
>> http://www.ebay.com/itm/380908663786
>> 
>> The need for an RTC + battery is still there.
>> These are super cheap; anyway.
>> 
>> http://www.ebay.com/itm/191276972230
>> $0.99
>> 
>> And 16x2 character LCD's are dirt-cheap
>> http://www.ebay.com/itm/121423925901
>> $1.55
>> Or, included with an LCD for $4.99
>> http://www.ebay.com/itm/221439853893
>> 
>> That'd make for: 3+1.55+1.05+0.99 = $6.59
>> 
>> CPU + screen + RTC with a I2c->LCD convertor
>> 

### This equation sounds good to me.

>> 
>> Buttons + connectors + sensors + relay/H-bridge will be required in
>> any application; no matter what you choose for; so the cost for these
>> is the same.

### The realy/H-bridge is something which we need to decide on soon.

>> 
>> 2: Easy to get parts
>> 
>> There are better CPU's that cost less; but have no easy ways to solder
>> them (SMD)
>> There are loose CPU's that would be smaller than an Arduino Nano, but
>> would cost more and would be harder to get and solder (SMD)
>> There are ways of getting the I2C RTC or the I2C->LCD controllers
>> seperately; but not as easily in single-unit items ...
>> 
>> That is the problem with electronics design when you are restrained in
>> money and/or availability.
>> 
>> There are two roads we can take:
>> 
>> If you decide to ONLY make the PCB and tell people 'Just get the parts
>> yourself', you need to make it as easy as possible to GET those parts;
>> so you need to tell them 'Find these modules; anywhere you can get 
>> them'
>> 
>> OR
>> 
>> If you make the PCB and sell it *with all the parts included*, you can
>> then choose to get more hard-to-find parts for the design. Stuff that
>> would be hard for 'normal' people to figure out how to get, but easily
>> gotten via Mouser/Digikey/Farnell/etc.
>> However, this might conflict with point 3: it should be easy to build.
>> Putting a Atmega328 and/or i2c RTC-chip on a PCB *might* be a bit more
>> than what people are willing/able to do.

### I would prefer the second way = PCB with parts. I wonder how much 
would it help if we found some agreement with place like SparkFun which 
would put our "product" on their shopping list. Do I remeber correctly 
that they do also soldering of the kit parts is an option (for extra 
cost)? Shall I go forward and get finally in touch starting to 
negotiate?

>> Point 3: Should be easy to build
>> 
>> Here, the same thing applies as with point 2 above.
>> It might be nicer to have a small and compact design, with all the
>> parts on one flat PCB.....
>> 
>> ..... but the parts might be hard to find, cost more than
>> parts-on-a-module, and will be harder for people to put on the PCB.
>> 
>> 
>> The other approach is to make a PCB that has foot-prints for all these
>> modules; making it easy to simply solder some headers on the PCB,
>> connect the right modules , connectors, etc. and then you're done.
>> This will be easy, fast, and it will not require us to put 'complete
>> kits' together. You can simply point people to where they can get this
>> stuff online.
>> 
>> Note: for at 31c3, you can of course make complete kits with all
>> modules included;... but later, if people want more, you can simply
>> sell the PCB's online and supply a list of ebay-links for the rest...

### So in other words we could have also online two versions right? One 
with complete kit with all modules included and one which would be just 
PCB and list of links where to get the rest, correct? Would be fine with 
me.

>> Point 4: It should be SAFE to put together.
>> 
>> This conflicts with with Point 1; should not be too expensive....
>> 
>> We could make a properly-designed relay-based board available; with
>> optocouplers, separated PSU, etc, as an alternative for using Solid
>> State Relays. But I think it would cost the same amount of money (or
>> more) to put together than what they ask for SSR's on Ebay...
>> 
>> I would hate to go for 'shortcuts' in this area; since we're already
>> talking about a DIY project involving heat, moisture and 
>> high-voltage.....

### So you basically recommend to use SSR's (H-bridge) for safety and 
long term performance. I'm for it.

>> Point 5: It should be safe to use
>> 
>> This ties in with Point 4 of course. Even with wet hands, sitting on
>> your knees in low light, trying to adjust the temperature of your
>> brew... it should still be safe...
>> This means separating your low-voltage logic from your high-voltage
>> stuff as much as possible. Again the consideration is to stick with
>> SSR's or at least an external, well-tested High-power solution
>> (H-bridge, whatever)

### The separation of low-voltage from high-voltage you suggested before 
and again it seems to me as a very good idea.

>> Point 6: It should be easy to modify.
>> 
>> This is something that is less important when the project is mature
>> and all the options are in there that anyone would want to have.
>> The more obscure your CPU is, the harder it'll be to find people
>> willing to stick time into it. Even to just change a few small 
>> things...
>> For that reason, Atmel Atmega (aka: arduino compatible) isnt a bad
>> choice..  Going for a more capable CPU with more pins would be nice,
>> but then you get at the 2560 controller which is just too 
>> expensive....
>> MHZ and ram are enough for what we do, it'd seem...

### Atmel Atmega sounds good worked so far lets go with ti bit further.

>> 
>> Point 7: Room for options
>> 
>> This has been my main concern lately.
>> The nice thing has been that everything fit 'so very neatly' in our
>> current design that any future options/addons would require more pins
>> on the CPU... which is not there.
>> This is the reason why I have been considering moving the LCD to
>> I2C... this frees up 6 pins, if i'm not mistaking.....Enough for
>> Software-based RS232 for a Bluetooth module...for example..
>> Or more complex cooling/heating options (or sensors).

### We will need bit more place if possible, humidity reading is on my 
mind more and more also wireless communication would be not just sweet 
but I think very handy - it would be more easy to have existing 
prototypes connected and getting the readings online so we could have a 
look on the data which I'm sure will definitely improve the group 
performance and involvement.

>> Conclusion:
>> 
>> Based on all of the stuff above, I'm looking at a design along the
>> following lines:
>> 
>> A PCB that has space for:
>> 
>> Power-connector + regulator
>> OR
>> USB-mini connector (for stable 5 volt)
>> 
>> Headers for connecting LCD; 4 wire cable with 
>> 5Volt+GND+i2c-clock+i2c-data
>> 
>> Header for connecting button-panel (2-wire: GND + signal-wire)
>> 
>> pin-sockets for Arduino-Nano
>> pin-sockets for RTC module
>> Connectors (screwterminals ? plugs ?) for sensors
>> Connectors (screwterminals ? plugs ?) for power-control (either
>> H-bridge or SSR.. whatever)
### pin sockets for temperature sensors and humidity sensor (hopefully) 
- I hope I word it correctly

>> 
>> Some resistors for the sensors
>> 
>> We could leave space for a (simple) FET-based H-bridge on the board
>> itself. This would require xtra 12V power-supply header. If designed
>> smartly, it'd be possible to simply stick the FETS into the right
>> holes and have it work ; perhaps by 'cutting' a few control-lines,
>> however, using solder-bridges.

### Have to leave this up to you and others, bit over my level.

>> The PCB can be designed to have the button-interface-board either
>> integrated (with traces connecting it without the need of a cable) or
>> broken off from the mainboard; connected via a 4-wire cable...(simply
>> cut with a good hobby-knife or use perforation)

### The LCD display may be quite a distance from the PCB board so the 
buttons should have that option too, sounds logical?

>> Extra options, like Bluetooth, etc, could be supplied by simply
>> putting the unused pins + I2C bus, SPIbus and Serial-BUS pins along
>> one edge; allowing people to connect extra boards/etc, using that.

### Have to leave that up to you and others, again bit over my level (I 
understand what you are saying but do not have knowlege and experience 
to really judge that).

>> 
>> The PCB doesnt need to be very large; probably less than 7x7 CM.
>> 
>> The biggest problem will really be the 'height' of the design. Since
>> using modules will increase the space required; as opposed to using
>> SMD-parts.
>> The LCD will likely take the biggest amount of space; with the
>> I2C->LCD backpack on it's back..

### Would using the cables for LCD and buttons modules help a lot to 
make the PCB more feasible?

>> That's the ideas so far.
>> 
>> Comments ?
>> 

### Well I did what I could, I hope it helps a bit! I'm thinking in the 
same time about the numbers of how many prototypes, how complex etc. for 
31c3 and later.

### I'll add parts to the list on the google spreadsheet soon and 
further improve the wiki reporting on the progress

https://docs.google.com/spreadsheets/d/1QKxhMj9P9zS8-tnlfEzmmUeURahy3w80DwVVSJW9odk/edit?usp=sharing

https://foodhackingbase.org/wiki/Experimental_Incubator/ei_prototype_designing

https://foodhackingbase.org/wiki/Experimental_Incubator/2.2_mamut


### Talk to you soon,

### Sincerely,

### FAA

>> 
>> 
>>> Please let me know at what stage you are, I will post to the lists
>>> afterwards and prepare the draft for the campaign. I'm sorry for
>>> not being more active lately but we have been moving the house and
>>> I'm now preparing/reconstructing our future brewing restaurant.
>>> Hope to hear from you soon,
>>> Sincerely,
>>> FAA
>> 
>> --
>> Frantisek Algoldor Apfelbeck
>> 
>> biotechnologist&kvasir and hacker
>> 
>> http://www.frantisekapfelbeck.org
>> 
>> "There is no way to peace, peace is the way." Mohandas Karamchand 
>> Gandhi
>> 
>> 
>> Disclaimer - there are other people who have access to this email 
>> account, please be aware of that it is part of the design. For "highly 
>> private communication" use algoldor at yahoo.com

-- 
Frantisek Algoldor Apfelbeck

biotechnologist&kvasir and hacker

http://www.frantisekapfelbeck.org

"There is no way to peace, peace is the way." Mohandas Karamchand Gandhi


Disclaimer - there are other people who have access to this email 
account, please be aware of that it is part of the design. For "highly 
private communication" use algoldor at yahoo.com