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 Posted: Jul 09, 2007 - 08:07 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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I said 7cm sq. draw a square 7x7 TA DA!! I will send you the photo though anyway
Jim |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first 
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Posted: Jul 09, 2007 - 09:06 PM |
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Joined: Dec 17, 2005
Posts: 1498
Location: Europe- Estonia- Tallinn
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| 7cm sq isn't 7cm x 7cm! Learn math! 7x7 is 49cm sq! |
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Posted: Jul 09, 2007 - 09:21 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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Depends on what side of the pond you live on!!! HA HA
ok ok ok, then the device is 7cm long x 7cm wide
Jeez, whaddah grouch  |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Jul 09, 2007 - 09:27 PM |
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Joined: Dec 17, 2005
Posts: 1498
Location: Europe- Estonia- Tallinn
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| I thought that was considered as a standard of some sort (SI maybe?) Oh well... another lesson learned. on both sides of the pond I hope |
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Posted: Jul 10, 2007 - 09:50 AM |
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Joined: Jan 03, 2006
Posts: 4414
Location: Hemel Hemsptead, UK
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Gentlemen, it's not a question of maths, it's a question of English usage...
7 cm square = 7cm*7cm = 49 square cm
7 square cm = 7cm*1cm = 3.5cm*2cm etc
If the 'square' precedes the metric, then it's part of the unit that's being counted, so 7 (square cm) if you like. If the 'square' comes last them '7 cm' is what's being squared... it's easy to get them swapped around.
Neil |
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Neil Barnes
www.nailed-barnacle.co.uk
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Posted: Jul 10, 2007 - 12:56 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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Thanks Teach
Jeez I suck at math |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Jul 10, 2007 - 06:35 PM |
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Joined: Jun 15, 2007
Posts: 110
Location: Gdańsk, Poland
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so how i understood the manner is 7 cm^2. seems like it's 7 times bigger than i thought. no way to put it on an arm, unless i really make myself a solar cell sweater.
i already got my useless cell, and i got a thought. how about breaking the cell in half and joining those halfs in series? that SHOULD give me 1V instead of .5V, but with less amperage. does it sound logically?
if that would work and my cell is actually producing current mentioned on the datasheet, i wouldn't need your cell anymore, Jim, but it's not a decision yet. thanks anyway for your help. |
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Not entirely familiar with AVR thingies... yet.
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Posted: Jul 10, 2007 - 08:57 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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I would love to watch you break the cell in half.
Oh by the way, If you still are looking to make a wristwatch with a solar cell and some supercaps good fun then. You will probably get arrested on suspicion of terrorism. The thing would look like a bomb!! 
Jim |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Jul 10, 2007 - 09:04 PM |
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Joined: Jun 15, 2007
Posts: 110
Location: Gdańsk, Poland
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i just need to know if that's going to work. breaking the cell in half is not a problem, the one i got is less than 1mm thin.
the supercaps i bought turned out to be... a bit bigger han i thought. each one is as big as 7 big coins sealed into one. guess i'll use this battery pack bloody-orc suggested. |
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Not entirely familiar with AVR thingies... yet.
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Posted: Jul 11, 2007 - 03:00 AM |
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Joined: Jun 15, 2007
Posts: 110
Location: Gdańsk, Poland
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ok, so to answer jim's request, and to make happy all you guys willing to help me, here is a quick features guide covering my project
basic overview:
a watch, named armwatch, because of its incredible size which doesn't matter until it fits one arm. to operate the watch no help of another arm is needed. also, a separate eeprom onboard containing images in suitable format which's content display is triggered by a button. everything solar-powered, so it must survive nights. possible lcd+avr on/off switch to save power at nights.
hardware ideas:
-using attiny or atmega, depending on i/o number and considering least power needed to operate
-lcd, options ordered from most cool to least cool:
*color lcd from nokia or other manufacturer
*fancy graphic mono if color are unreadable without backlight
-possibly backlight triggered by handshake, using trembler or accelerometer
-external rct
powering ideas:
-solar cells charging battery/supercaps and powering circuit. preffered as small as possible.
-using dc/dc step-up/down to stabilize power to 3.3V
-i'm considering using additional emergency supercap keeping rtc chip exclusively powered.
software ideas (please note i have't done any AVR programming yet):
-avr is being put to sleep and is waken up by rtc each second. the lcd content is updated and avr puts itself back to sleep. using highest clock frequency so it is put back to sleep faster. avr also reacts for button call to show graphics and to turn on backlight temporarily.
-or the same as above but running without sleep on dead slow clock frequency, like 32kHz (as long as it's possible with internal clock, otherwise the external one might be used, or rtc pulses)
-due to my serious troubles at university, programming will be done in old pal basic instead of studying asm.
stuff i already got:
-Philips 8583T RTC
-5x 5V 0.22F supercaps, but it turned out that they're huge, so don't expect me to use all of them  not more than three
-0.5V 70mA solar cell, currently figuring out how to boost voltage with current reduction.
stuff i keep an eye on:
-MSP-430SOLAR PANEL 2.4VDC 80mA with DC/DC voltage boost converter (posted by zauberer above)
-http://www.oomipood.ee/index.php?t=k_ki&i=FARNELL_1319725 (lithum battery posted by bloody-orc)
-Jim's solar cell, 49cm^2 so quite big.
Quote:
The cell produces 2.7vdc@3ma in flourescent light, and 3.6vdc@6ma in bright sun.
current figuring out process results:
-my solar cell gives too poor voltage, so how about splitting it into two pieces and joining them in series to get higher voltage and lower current? i've seen on auction a broken pieces of solar cells and the guy claimed it's working.
-the same might be done with jim's cell to fit it my arm's size and power needs. but just please tell me if it's realistic at all.
-while using my poor cell no step-down will be needed; although if i wanted to use jim's, both step-up and down features would be essential because his cell is exceeding 3.3V rate.
phew, i guess that's it.
(added few minutes later)
my 66th post. it makes 2/3 of satan's number, isn't it? |
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Not entirely familiar with AVR thingies... yet.
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Posted: Jul 11, 2007 - 01:00 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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Matcom,
Since your university career has hit a speed bump. Welcome to JIM-U!! Class is about to begin.....
1) Good!! you have a menu of what you want this 'wristwatch' to do. Pick the hardware first. The software is easy.
2) Make a decision on the display you are going to use, and stick with it. THIS IS IMPORTANT because the type of display and it's support hardware will decide many things going forward. My suggestion is a simple display, and if possible serial controlled. It uses less I/O pins.
3) Pick a processor and also stick with it!! ALSO VERY IMPORTANT. My suggestion is a Tiny that uses 8pins(hence why I suggested a serial lcd).
4)You are spending WAY to much time on the power supply. Keep it simple. I sat down, designed, and then built the power supply that I think will do exactly what you want and I used common parts that are easy to get. I did not use any funky switching supply chips etc. Just a solar cell, big capacitor, and a few diodes.
5) DO NOT CUT/BREAK THE SOLAR CELL IN HALF! The only thing you will get for doing this is broken glass and a dead solar cell. The cell you have has always bugged me 0.5v/70ma sounds like either an old cell or you are doing something funky in testing. The cell I offered you is indeed 7cm x 7cm, so it is 49 sqcm in size. I hope that makes all the math freaks happy now! 
6) Drop the RTC chip. It is not needed. Use it in something else.
7) Don't worry so much about making this thing wristwatchsize right off of the bat. I generally try to do my prototypes in DIP as much as possible as it is easier to get probes on pins etc. Then make it small. This way going forward, if the prototype works you then have a solid base to work off of. This is especially important if you are new at this.
Spend more time with your girlfriend and your cat! Your kitty likes it's head scratched, and I am sure your girlfriend is a lot more fun to play with than a solar/supercap powered wristwatch!! Seriously, walk away from this thing once in a while. Whenever I get frustrated I go do something else. My wife usually has a long list of stuff for me.
Ok, now that you have the first class' notes, and I am not goint to do your homework here is your assignment:
1) Pick the display
2) Choose a micro
3) draw a basic schematic IN PENCIL. I hate pens, difficult to erase boo boo's.
4) Ask yourself....Is Jim out of his mind?(answer:YES!)
Ok, that's all for now.
Jim
Oh by the way. The cat usually likes the scratch just behind the ears! |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Jul 11, 2007 - 07:55 PM |
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Joined: Jun 15, 2007
Posts: 110
Location: Gdańsk, Poland
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thanks, master. i think i'll sketch it after couple of lessons of circuit theory i need to learn for september anyway. wash and go, that's what i like. not to offend you but you seem to be quite sane for me in the meantime i'll seek for an lcd in gsm sevices.
the solar cell parametres is what i've read in datasheet, never checked it myself. but i will.
what do you exactly mean by dropping RTC? what do you suggest to use instead? i've noticed that running atmel all the time is pretty hard to power.
both our cats love rubbing their faces and ears, but after castration both turned into sort of... gay? they prefer scratching just next to their tails now. i'd rather do some girl's task than THIS, like washing up. |
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Not entirely familiar with AVR thingies... yet.
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Posted: Jul 11, 2007 - 08:34 PM |
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Joined: Dec 17, 2005
Posts: 1498
Location: Europe- Estonia- Tallinn
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you can run the AVR from 32,768kHz. or at least the timer (some chips can have 2 crystals connected to them. one for processor clock and the other one for timer.) Get yourself a good big chip; I don't think you can do it all with just 8 pins. I was thinking of tiny26L or something similar (although it doesn't have the ability to use 2 crystals AFAIK).
anyway good luck with your clock, LCD and gay(?) cats. |
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Posted: Jul 11, 2007 - 11:34 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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Mactom,
You will not need the RTC. TRUST ME.
Just do your (4) homework items and then we move on.
I will give you one hint: Look at the specs on the Tiny micros running at 32khz.
The cats are not gay, but I can understand them being pissed off at you for having their 'nad's sliced off.
Remember, one step at a time dude |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Jul 12, 2007 - 12:30 AM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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| Here is the solar cell everyone want's to see!!! |
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Posted: Jul 12, 2007 - 02:24 AM |
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Joined: Jun 15, 2007
Posts: 110
Location: Gdańsk, Poland
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the picture is not a surprise when we know the dimentions already, but compared to this avr its... bigger!
well, Jim's right, the topic should be more about powering right now, so let's put chips and crystals aside, at least until i start a new thread in projects room. |
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Not entirely familiar with AVR thingies... yet.
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Posted: Jul 12, 2007 - 04:31 AM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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Mactom
My homework has everything to do with powering!! How do you design a power supply if you do not know what the requirements of it are?
In other words, you need to select the micro, display etc. first. Then work on the power supply, then look at both and see if everything is what you are looking for and adjust accordingly.
You answered task 4 in the homework, now do the first three
You will notice I did not include the power supply in the three things
Jim |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Jul 13, 2007 - 10:04 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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Mactom:
How are you making out with your schematic and component selections?
Jim |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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Posted: Jul 13, 2007 - 11:08 PM |
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Joined: Jun 15, 2007
Posts: 110
Location: Gdańsk, Poland
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easy, jim, haven't found an lcd yet, so it's a trick to pick suitable uC.
tell me, how much i/os will i need? seems like nokia lcds have command input, command/data switch and clock input. moreover, one button, possibly an accelerometer, and eeprom on some ios are making 6 or more of them necessary overall.
is there something wrong? |
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Not entirely familiar with AVR thingies... yet.
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Posted: Jul 15, 2007 - 07:52 PM |
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Joined: Apr 20, 2007
Posts: 6065
Location: Long Island New York
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Don't know what you mean by is there something wrong.
The lcd is your first area thaat needs to be resolved, then the micro. I cannot tell you how much I/o you will need as I do not have a parts list that you want to use.
you are doing well. Pick the display first and see what is needed to run it. Feel free to tell me the part numbers and I can look them up and see where you are going
Jim |
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Jim
I have decided that I am no longer going to plan anything in advance. In a court of law this is called Pre-Meditated, and does not look good for the defense.....
Timer function not working properly? Check CLKDIV8 Fuse first
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