Bcoz I like computers ive been asked to build a tree with lights.
Anybody got an idea where i can start. What processor? What speed? How much memory?
Bcoz I am impressed with your knowledge of slang abbreviations, not impressed with you using them in a professional forum
ive been asked to build a tree plant as seed
Anybody got an idea where i can start. What processor? What speed? How much memory? in additionto Andys answers I want to add the following: either a) make sure the uC outputs can carry enough current for your 'lights' (LEDs ?) - OR - b) use interface chips from e.g. Allegro that can handle the current
re a) there are 3 limits: 1) max I/O current per pin 2) max I/O current per port 3) max I/O current for the chip do not exceed either.
Erik
Unless we are talking about a very small tree, I would assume that each processor pin would have to control multiple LEDs (or lamps) so a couple of open-collector/open-drain transistors or buffer chips would help greatly. Then you may also connect several LEDs or lamps in series and drive them from a voltage significantly higher than the uC supply voltage. For example 5 LED and a resistor in series driven from 12VDC, or you could use colored 12V light bulbs.
Erik - can I have a go in your time machine after you're done with it? (or maybe you could set it so that I can have a go before you've even started...)
"use interface chips from e.g. Allegro that can handle the current"
For just a simple christmas tree homebrew project, I just use discrete transistors; each transistor is driven from a port pin, and switches a string of LEDs - with a 24V supply, you can have 10 or so LEDs in a string...
rand() is perfectly adequate for the twinklink: http://www.keil.com/support/man/docs/c51/c51_rand.htm
By the time I managed to coerce the forum into actually accepting the post, I see that Per had pretty much said all of that!
"Bcoz I like computers ive been asked to build a tree with lights."
Sounds like the logic of a non-engineer to me!
Did I hear someone whisper the word salesman ;)
A quicker solution might be to buy the ready made parts (tree and lights) from your local Woolworths.
"A quicker solution might be to buy the ready made parts (tree and lights) from your local Woolworths."
Sadly, it would probably also be cheaper!
eg, www.woolworths.co.uk/.../index.jsp
160 LEDs for under GBP 19 is only about 11p each, including wire and power supply, etc!