Experimental Incubator/ei prototype designing
2.1 "Mamut" - Current prototype of experimental incubator
One of the most important things which we have to decide on is "how do we want to do it?" meaning mostly in this case the practical way of building up a prototype. Below are strategies which we were implementing so far.
- Industrial prototyping
Inspired by my (Algoldor's) friend Arnd we choose to go by "industrial prototyping". Simplified: get well supported and functional parts for bit of extra cash and build up the first functional prototype from them. Afterwards when the prototype is working, start to break it down part by part redesigning them or using another cheaper/more feasible variants shaping the incubator to your like, bringing the costs down. This approach seems to be bit more expensive to start with but it ensures that even less experienced contributors to the project would be able to build their functional experimental machine, having than what to work with which I think is crucial. For more info please check this page created at Techinc hackerspace by Arnd. Till we get a proper PCB design and assembled kit you need to have some certain electronic skills set to get "smoothly involved" in the project. The more easy to put together kit option should be ready for 31c3 in December 2014.
Short time goal - 3-4 prototypes 2.1 mamut build - deadline end of April 2014
By the end of April we want to have three to four prototypes of 2.1 mamut running in different locations so we can test in reality the design which we choose to apply both hardware and software. The aim is to measure, display and control temperature, both heating and cooling using the kit which we presented at 30c3, sharing updates through our forum and incubator mailing list, software updates especially at Github. Next step after few months of testing, reporting on the progress and summarizing of the results will be design of the PCB boards which are base for 2.2 mamut kit version. This should be due at the end of July or during August.
Medium term goals - PCB and kit design 2.2 mamut - summer to winter 2014
After few months of testing of the first prototype 2.1 mamut we will design printed circuit board (PCB board) which will be base of our experimental incubator kit - 2.2 mamut prototype/model. This one will be assembled and tested for two or three months, aiming to have all the bugs out by end of September 2014 if possible, mid of October latest. By the end of November the final run of tests needs to be done resulting in final version of the experimental incubator 2.3 mamut kit version confirming the final design and ordering larger quantities of components (latest end of November) which will be presented and circulated at 31c3 congress as Experimental Incubator 2.3 Mamut.
- Parts needed to build up prototype/kit for 30c3
(parts suggested based on industrial prototyping scheme)
|Component||Function||Model Specifications||Amount||Cost (€)||Purchase links||Component Suggested by|
|Arduino Board (clone OK)||easy prototyping||???||1x||15||DealExtreme||Arnd|
|Arduino prototyping shield||for easy prototyping||???||1x||2||DealExtreme||Arnd|
|LCD Display||display data||???||1x||7||DealExtreme||Arnd|
|Temperature sensors||to measure temp.||???||2x||8||DealExtreme||Arnd|
|Solid state relay||switch on/off 220V elements||???||2x||6-10||DealExtreme||Arnd|
|H-bridge||changing polarity of peltier||???||1x||13-16||Ebay||Arnd|
|RTC (real-time-clock) module||keep count of time||DS1302 based||1x||3||DealExtreme||Arnd|
|Connectors for temp-probes||connect the temp-probes||???||2x||1||DealExtreme||Arnd&Erwin|
|Pin Headers for Arduino (package of 5pcs)||to connect boards||???||1x||5||DealExtreme||Arnd|
|Thermopaste||to connect heatsinks to peltier||???||1x||5||DealExtreme||Algoldor|
|peltier element||for heating/cooling||???||2x||8||GM electronics||Lars/Algoldor|
|cooler||for heat distributiong||???||2x||???||Arctic||Lars, Algoldor|
An overview of pins used - 2.1 Mamut
An overview of Arduino/Atmega328 pinouts
The following table then emerges:
D0: Serial RX D1: Serial TX D2: SSR1 D3: SSR2 D4: LCD D4 D5: LCD D5 D6: LCD D6 D7: LCD D7 D8: LCD RS D9: LCD 'Enable' (might be optional) D10: LCD backlight control (might be made optional) D11: One-wire bus 1 (first temp-probe) D12: One-wire bus 2 (second temp-probe) D13: Free (see note below about LCD and buttons)
A0: LCD Buttons A1: Free A2: Free A3: Free A4: I2C SDA-line for DS1307 A5: I2C SCL-line for DS1307
This leaves one digital pin free in a 'plain and simple way' of connecting two SSR's and two temperature-probes. We could free up two digital pins with the LCD, even more if we move it to an I2C-based way connecting it (saves another 2 to 3 wires, I believe), at the expense of more code/parts. As it is, it's not required for what we want to achieve with the device right now.