Hi, I know that this issue has been discussed before and that there are some websites devoted to this topic and i apologize if i am repeating a topic but i am still having a difficult time trying to understand.
What i want to do is mount an Atmega 168 chip on the back of a r/g 8x8 display with the absolute minimum hardware and use these as Christmas tree ornaments.
If i understand correctly all i would need is as far as the arduino is concerned would be the chip, 2 inputs for power and 9 outputs. Would i need a crystal or any other parts to make the Atmega 168 chip work?
Thamk you and again i apologize if i am repeating a topic
You should have some bypass caps on the AVR chip.
To do an individually dot-addressable 8x8 matrix display that has two colors per dot, you will need more than 9 outputs. The two colors of LED chips make it essentially a 16x8 array (for example, see the data sheet associated with this one: LED Matrix - Dual Color - Medium - COM-00682 - SparkFun Electronics), and the pre-wired nature of such arrays tends to make "charlieplexing" impossible. So you probably need 24 pins...
8 shift registers?
I'm currently doing a project with 3, and one sink driver. It all fits on a 3*2 inch protoboard.
sciguy - A TPIC6B595 is an Power Logic 8-Bit Shift Register
I imagine Richard Croley probably meant to write "eight bit shift-register drivers", rather than "eight shift-register drivers"
GB-)
I am using the 168 chip because it is the only one i have lying around. I took a look at the attiny 13 and it looks like a good idea but can it be programmed using my Arduino Duemilanove board, i really can't afford to buy a separate programmer unless i am going to get alot of use out of it.
I figure that if i only use the red or green then i should only need 16 outputs, is this correct?
Also westfw mentioned some bypass caps, what are those,how many would you think i would need, where should i put them?
Sorry for the stupid questions but i am obivously not very smart about these things, at least not yet.
i really can't afford to buy a separate programmer unless i am going to get alot of use out of it.
Hsve a look at MegaISP
You can use your Arduino as an ISP programmer.
I figure that if i only use the red or green then i should only need 16 outputs, is this correct?
Yes, though you might want to use a driver, like a ULN2803 on the 'columns', to sink more current than an unassisted Arduino pin.
HTH
GB