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newbie with a new project

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L0D|Mr_B

New Member
first post - [quote Dr. Nick Riviera] Hi everyone! [/quote]

:D

ok, to business.

i have a "small" project of modding my PC, well, actually i'm building the whole case from scratch, to fit some rather "explicit" water cooling gear. I mainly post at www.pclincs.co.uk/Forums but a dedicated electronics forum is what i'm after, the other is for mainly pc related cooling, oc'ing and modding (windows and lights, etc), then i found this place ....

basically, i want to build a fan controller. sounds simple enough. but i want a clever one :)

I'm going to be driving 3 120mm fans from the one button (push to make with blue-led behind it), which when i push once puts the fans on 5v, push a 2nd time to put on 7v, and push a 3rd time to get the full ear-drum burstin 12v, a 4th press goes back to 5v etc etc. the led is gonna do some fancy flashin to when press, you get the picture i hope - i'm after a button which is real eye-candy! (ok ok, i'm a tart - hands up!!)

when initially switched on, it's gotta give the full 12V to the fans for atleast 4 seconds to ensure the fans have started spinning as there is no feedback on the 120mm's to monitor. once that 4 seconds is up, will default to a specified voltage (5,7 or 12) depending on a link array i'm gonna use. so the way i see it the circuit i'm building is gonna have 3 inputs (switch and 2 for links) and 3 outputs (2 for relays and 1 for led). power supplies for this will be of the ATX psu, so will have 12V,5V and 0V rails supplied.

the main current handling is gonna be done via relays, cos at 12V each fan can draw an initial surge current of about 2A, nominal 1A @ 12V, so it's gonna be switchin 3A nominal with a potential 6A spike at switchover. thinking diode logic off the IC to transistors to drive the relays.

to control, i was thinking pic16F84, and this is where my problems and questions start. i'm not new to electronics, have a HND in it, so my ohms law is pretty sharp! done a bit of work on Z80's, alot of work on 68000's but absolute bugger all on pic's. i've downloaded the datasheet and it seems a nice simple little device, but here we go :-

1/) firstly, code generation. can anyone recommend a tool (free one pref - well c'mon! everyone want something for free, you did want me to be different did you? :D). i guess the tool should output bin and hex files. advice on this whole process would be greatfully received. would like something which will do assembler, worst case machine code. compiling for errors would be a bonus.

2/) secondly, uploading - i understand i'm gonna have to buy a programmer of some sorts. fair enough. i stumbled across this -> http://www.quasarelectronics.com/3128.htm. is it any good? i prefer USB over serial due to connection issues, and this looked a good package. any comments, or maybe a better tool. suggestions if you think you have a link to something better please :D

3/) i'm gonna be building on veroboard cos i dont have access to facilitys to etch, unless someone here is willing if i pay them (not joking there btw). this leads me to the next array of questions - anyone know of any good (and free btw :D) schematic capture and pcb layout software? when i was at college, i "borrowed" a copy of BOARDMAKER which was dongle cracked, but i've since found that it will only run on a 486!!! thats how long ago it was since i did this sorta thing!!! ive scanned the net, but what ive found is either time locked with no saving options, or simply PANTS!

any other suggestions like "dont use a pic, use ..." will also be taken on board. it's been so long sinse i did this sorta thing, i guess i'm after a sanity check too :D

B
 

Exo

Active Member
1)
Microchip's MPLAB IDE, a full developement tool for pics, complete with assembler and debuggers is available for free at microchip's website
www.microchip.com

There is a also a free picbasic compiler floating around on this forum somewhere in the PIC/Basic programming section

2)
You could buy a programmer, or when you are at it, make one yourself.
Look on the net for Tait style programmers.
Another good programmer is the P16pro40 wich works well with the free winpicprog... all available on www.winpicprog.co.uk

3) I use eagle layout editor for Scematic/PCB creation. Not free, but you can get a trial at http://www.cadsoft.de/ (it has limitations , like a maximum board size and stuff, but it will not expire or something, so it keeps working)

(also, cracks are available :twisted: )
 

bmcculla

New Member
If you're want a nice fan controller you should check out Maxim's MAX1699. Its an I2C controlled fan controller with PWM output. The I2C bus is compatable with the SMBus which can be found on a number of motherboards. This would allow you to control your fans with a dab of software on you PC.

On making PCB's PCBExpress.com makes good boards for cheap. I've also used APCircuits. For both of these plases you send them your design files and they send you boards a couple days later.

Since you are familiar with the Z80 you might want to look at Zilogs new controllers The EZ8 Encore looks slick and has a cheap Dev. Kit.

-Brent
 

Exo

Active Member
bmcculla said:
If you're want a nice fan controller you should check out Maxim's MAX1699. Its an I2C controlled fan controller with PWM output. The I2C bus is compatable with the SMBus which can be found on a number of motherboards. This would allow you to control your fans with a dab of software on you PC.
-Brent
This depends on your chipset... Not all chipsets allow user software to play around with the I2C interface
 
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