im actually supposed to be getting snow here today.. its gonna be fun workin outside...
i just looked it upo, and we have a snowfall warning here today
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im actually supposed to be getting snow here today.. its gonna be fun workin outside...
i just looked it upo, and we have a snowfall warning here today
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Wow! You get warnings! Actually, it's 62F right now for me. Where are you at anyways? I see AB,Ca. I'm in Minot, ND. If you're getting snow right now, we'll probably get it in about 12-18 hours.Originally Posted by dragons_fire
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right now, its 3.3C wind is 18KM/h and we are supposed to be getting 6" of snow this evening... im in alberta canada...
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I know you're in AB,Ca...that's why I put AB,Ca. Where at in AB?
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NOPE!!! I like my sand. It gets to 120+f here in the summer, but I do not have to scrape it off the windows or shovel/plow it out of the way.Want me to send you some snow?
At the moment it is about 85, with a slight breeze
Dave
Always wear safety glasses while programming.
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120+ ... my thoughts... you can always start something on fire to stay warmNOPE!!! I like my sand. It gets to 120+f here in the summer, but I do not have to scrape it off the windows or shovel/plow it out of the way. At the moment it is about 85, with a slight breezeand it's more expensive to cool than it is to heat.
You might not have to scrape the sand off your windows, but, over time, the sand will scrape the paint off your car!
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Cooling is not as bad as one might think, low humidity.120+ ... my thoughts... you can always start something on fire to stay warm
You might not have to scrape the sand off your windows, but, over time, the sand will scrape the paint off your car!
No paint on car, thats camouflage for us. Half way between Yuma Proving Grounds and Luke Air Force Bombing Range
Dave
Always wear safety glasses while programming.
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im in calgary alberta.. when you wrote CA, i thought maybe you thought i was in california..
its just starting to rain/snow right now. thats why i switched from big outdoor robots to making small indoor robots...
im not sure im happy with my battery choice for this bot. its a 730mAh 7.4V li-poly battery. my biggest issue is that its really not good to drain them past 2.5V/cell, so this pack can only go down to 5V. i may need to set up an ADC to measure battery voltage and have it shut down if it gets too low. and that gives me one more thing to worry about,.. i might remake the body so that its big enough to fit an alkaline 9V (its fibreglass and only took about 10 minutes to make). if i go to an alkaline, i cant charge it from a base station though, and nicads or nimh dont have much capacity.. alkalines are just ofver 500mAh at 9V, and the nicads are about 150-200 at 7.2V and nimh are about 300mAh at 7.2V....
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You've got the base set up so you can stack PCB's on top of it. Make a board that'll hold a pack of AAA NiMH batteries laid flat and sits on top of your other PCB. They go up to about 700mAh in the AAA types. As far as shutting down at 2.5v/cell on the Li-Poly packs. Easy to set up an ADC pin to handle that for you. Kill the motor drive once you hit about 2.8-2.9v/cell, and that gives you plenty of time to put the thing on a charger. Have it beep or something to let you know.
I most definetly wouldn't go with alkaline batteries. It'll end up like a kids toy...run it for 5 minutes, then change batteries...
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i dont really have a problem with stacking it vertically, if i do, i can actually fit about 5 AA batteries (nimh are 1800-2500mAh) which would give me 6 volts for the motors and lots of capacity for it.. and they are rechargeable..
only problem with that is finding a 5-cell holder. or i can make a 5-cell pack, and mountit somehow, but it would be nice to use a holder, cause then i can change them out quickly while im testing...
PS. we have freezing rain mixed with snow now!!!
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double post!!!
Last edited by dragons_fire; - 19th April 2007 at 00:32.
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And it's heading my way!
Swap the AA's for AAA's and you'll get a few more volts for the motors.
Less capacity, but maybe you can parallel them...
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thats what i did... i just picked up 2 x 3-cell AAA holders.
im going to change stuff around a bit, and add the switch and Vreg to the board with the battery holders..
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And then...and then...and then...you could...ummm...ummm...put another PCB on top of that one...and then...and then...and then...put 9v worth of small solar cells on that...to..umm...ummm...umm...trickle charge the AAA's...
Are you planning on using a linear reg or switch mode?
Check out the LM2825-xx types. Self contained, DIP28/.6", a bit thicker than normal DIP28 types, but have the coil and everything inside the package. And it'll save you some power.
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to be honest, i dont really know much about voltage regulators (or anything). im using this reg: http://www.st.com/stonline/products/...035/LD1084.pdf
it may not be the best, but ive used them before, and i have some laying around...
and... and... thats why there is so many headers with pins going nowhere right now.. just so i can add more boards on top...
should mention i did look at solar panels.. one the size of this robot, would output around 20mA at 6v. just not worth it.. it would take forever for that to charge enough...
Last edited by dragons_fire; - 19th April 2007 at 05:20.
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That's a linear regulator, but it is a low-drop-out type. Don't know how much you know about regulators, quick explanation:
Linear - takes voltage in, say 10v @ 1amp, you want 5v @ 1amp, it dumps off 5v @ 1amp as heat, 5watt wasted...in this case, 50% efficient.
Low Drop Out - All regulators need some overhead to work right. A 5v regulator might need 7v at full load to work, below that, things go haywire. A Low drop out type might only need 5.5v input under the same conditions
Switch mode - takes that same voltage in, turns a mosfet on/off really fast and uses an inductor to help keep an output cap charged up to the regulated voltage, but there's just a tad bit of ripple on the output (which can be smoothed out). It's not 100% efficient, but depending, they can approach 98% under the right conditions.
Well, I was just thinking that there will be days when it's sitting not doing anything...and if you had any laying around, they'd help...should mention i did look at solar panels.. one the size of this robot, would output around 20mA at 6v. just not worth it.. it would take forever for that to charge enough...
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to be honest, i really dont know that much about electronics in general.. i learn by seeing what other people have done, and putting stuff together and trying it till it works..
that switch mode regulator, cost almost 20 times as much, and i dont really have much room on my board for it, (it looks like its about 5 times the size).
we have lots of floor area that gets sun most of the day, so its not entirely out of the question for solar panels.
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Guess I should've checked the price before I mentioned it. Digikey is getting $30USD for them nowadays. Back when I bought them, they were only about $8USD. There's got to be a better option out there.
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so here it is... power board is done, and works great... the main board underneath, is the old one thats not working.. i havent made a new one yet..
batteries are duracell AAA 1.2V 1000mAh. i havent measured current draw on the motors, but the datasheet says 50mA no load...
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new board is made, it turned out a hole lot nicer. everything powers up ok except for when i put the chip in.. i did find a short in the old board, so maybe my PIC is destroyed and thats why its not working now..
i measure "open" across vss and vdd with no PIC, and 1M ohm with PIC.
i dont know what im doing wrong, ive been over the pin-outs a million times, and everything seems right..
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i just realized that im using a PIC18LF6585, not an 18F6585. from what i have read in the dtasheet, the only difference is that the LF will work at lower voltages, but i think it will still work at 5V.. does anyone know if thats true or not?? if its not meant to run at 5V, then that would explain my problem...
i dont get any heat now, but it pulls my voltage down to about 2V when the PIC is in it...
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I can not comment about the differences in the two chips.
Have you used this v-reg before? This is one part you may want to breadboard. I looked at the data sheet and did not see a minimum voltage, are you sure the batteries are charged. Try putting a known load on the v-reg and watch the output. Could be something wrong with the v-reg or cap size.
It still might be a good idea to build an adapter and bread board the PIC. Try another power supply.
Just looking back to basics. To many variables going straight to finished product.
Dave
Always wear safety glasses while programming.
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i just used my "power board" to power a 16f877A, the motor driver and both motors.. works good.. i would prefer to use teh 18f6585 because of # of I/O, memory size and speed..
i might just go back to using a 877A for now, just because i know i can work it..
i just dont know what else to do to get this 18f to work...
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You've got a 6 cell NiMH (or NiCad, doesn't really matter). Open circuit, they've probably got 1.3-1.4v per cell when fully charged. You put a load on them, they'll probably drop down to, say, 1.1v per cell, maybe less. As I stated earlier, with a regular linear regulator, you need a certain amount of 'voltage overhead' to keep the regulator working correctly...usually about 2 volts. Anything less and your regulator basically freaks and starts outputting a lot less voltage.
So, you've got that 6 cell pack, roughly 6.6v under a load, more likely less since you're driving motors (50mA no-load doesn't mean squat when you're trying to drive this thing around).
Looking at that datasheet you linked to earlier (Page 11, Figure 11), you need at least 6.1v @ 1.5amps of load to keep the regulator happy.
Try this for grins... lift the Treadbot up so it's wheels can free spin, power it up and see what your voltage is.
I'm thinking that you're going to have to run an 8 cell pack of AAA's instead of 6 AA's.
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well, right now my power board works great with a 16f877a, the motor driver and the motors. (both motors togetehr are around 200mA at full speed). when im playing with the 18f6585, i dont have the motors, motor driver and all the other little stuff isnt hooked up. just the pic and an led!!! when i measure the resistance across the board, (with the PIC in) i get about 1 Mohm. input voltage is around 7.4 (fully charged cells). but ohms law says that 5V going through 1Mohm, there is almost no current... not a short... even when i hook my multimeter up, it shows no current.. but the voltage drops right down to around 2V
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The PIC that is giving trouble is the same one that was in the boad with a short?
What is the exact part number of the PIC giving trouble? I will get one or two and try.
Dave
Always wear safety glasses while programming.
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Ok, all notes noted....
You're using a '6585 now...
You didn't by chance get the pinouts between the TQFP and PLCC pinouts mixed up did you?
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yeah, i was trying to use a 6585... i did use the pLCC pinouts. i need to look into that some more though, cause i was thinking that maybe my pins dont match.. in expresspcb, when i click on a pin, it tels me the #, i think maybe its wrong, or it might be different than my socket, and that could be causing my problem..
nothing heats up anymore, i just lose voltage, and my "power" LED dims. maybe this PIC is shot from my mess up earlier, that its not allowing things to work now..
i put this project on hold for the weekend, im building a lightning trigger for my DSLR camera. sensor works great on the breadboard, im just trying to figure out my optoisolator to keep my circuit seperate from the camera... im using a 16F88 for this (i was going to use a SMT 12F675, but i have lots of room and lots of 88s).
im still thinking about my robot, so i didnt give up on it, so im open to any suggestions.. im trying to avoid making an adaptor to breadboard it first.
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Hey Dragon,
It appears that all the VDD and VSS on your PCB are backwards.
Here's a 68-PLCC socket and 18F6585 pinout
<table><tr><td valign=bottom></td><td valign=top>
</td></tr></table>
and here's your PCB
I haven't checked the rest of the pins.
HTH,
Added: Oops, and PIN 49 is VDD
AddedMore: No doubt the original chip is Fried.
<br>
Last edited by Darrel Taylor; - 23rd April 2007 at 01:08. Reason: Pin 49, Fried (not baked)
DT
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Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
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thank you so much!!! i have been over this board so many times, with the datasheet in one hand, and the schematic in the other..
i new it had to be something stupid like that, i just couldnt find it..
i definately feel like a retard now!!! 2 different boards (designed from the beginning both times) and a weeks worth of going over and measuring..
thanks again!!!
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**** happen my friend. I guess you will'nt do it again
Last edited by mister_e; - 23rd April 2007 at 01:36.
Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
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Never done THAT before.... Yes I have.
(that's how I knew to look for it)
<br>
DT
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it is actually my first time doing that... but im sure it wont be the last..
at least i enjoy making the boards, i think its part of the fun. i also only soldered on the basics, so its not much of a loss of money...
i cant believe i didnt notice it.. i started from scratch on the second board, and i still didnt get it right...
thanks again!!
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Good..you found the problem!
You would think it wouldn't be that hard to cut some traces and run a few jumpers to fix the board. It's not optimal, but it should work.
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it may not be too hard to cut some traces and run a couple jumpers.. i like having everything nice and clean.. and like i said, i enjoy making the boards... later on, i will try to post a pic of my 16f88 controlled lightning trigger for my camera. seems to work using a camera flash, hopefully it will work with lightning....
i used a photocell (resistor) connected to an ADC pic on the PIC, and it takes 2 samples, and compares them. if the second one has a greater value, then it triggers the camera. if i use a flash (disposable camera parts) it will take a picture and capture the flash, so it should be fast enough for lightning...
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I'd bet the photocell won't respond fast enough. A camera flash is usually quite a bit slower than lightning.
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well, i have only breadborded it, so i can always change it to a transistor.. http://www.solorb.com/elect/lightning/
i dont think that a flash is slower than lightning. i may miss the initial bolt, but i have gotten a few stikes by just pressing the shutter button when i see the flash...
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Are these your pics, 'cause if they are...
COOL...just plain COOL!
Can you keep triggering the shutter for like 5 seconds (give or take) after the initial hit? Might get some neat shots there too...
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im using a rebel XT, it will take aprox. 3 Pictures a second.
two of those pics were taken out my bedroom window, and the other was on a camping trip. it was on the other side of the lake. usually i take around 500 pictures during a thunderstorm, and i get about 15 "ok" pics of lightning...
this trigger im making, uses one of about 10 16f88s i have laying around, a 9V battery and it all fits inside an altoids container that i made a mount for to fit on the hotshoe of my camera. if it doesnt work for lightning, i will just modify it to fire a flash to use as a slave.
thought i would mention that the wire o nthe left side of those pics, is a wire for my video camera that i had mounted on the roof that i wanted to eventually stream onto the internet.. another one of my projects that never got finished...
Last edited by dragons_fire; - 23rd April 2007 at 05:04.
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