Powering the Olimex AVR-H128?

Development Boards MicroMod
1

First off apologies for being a newbie. I’m doing a lot of Google research, but am failing to find the info I need.

Basically I want to use an ATmega128 in the simplest way I can to power about 50 LEDs. Hopefully I can do it without having to design a circuit board, or buy a £100 development kit with bells and whistles (and LCDs…!) I don’t need.

What I’m currently looking at is the Olimex AVR-H128 Header Board, since it already has an oscillator and ISP connection built in. I figure I should be able to plug in some power, connect it up to an Olimex parallel port ISP lead, and away we go.

However, I’m having trouble finding information on how exactly I power the board. It has a built-in voltage regulator, and I know the chip expects +5V. So does that mean I need to power it with enough 1.5V cells to be less than, equal to, or greater than 5V? And does the board power input go as standard through the regulator, or do I need to wire that up in some way?

I’m also hoping to power 50 * 20mA LEDs, so am presuming that the AtMega won’t be able to do this directly (I remember reading that the regulator had a max current throughput of 200mA, and I’ll need 1A) and I’ll need to have some sort of transistor to boost the control signal current. So each external LED board will have a transistor of some sort, a limiting resistor, and the LED.

Any help you can give would be great!

2

there’s a a spec on the max power for a mega chip. It’s such that you cannot have every I/O pin sourcing/sinking simultaneously.

So for that many LEDs I’d think you’d use some sort of shift register with a buffered rank output. Or one of the special purpose LED driver chips for those moving letter displays

3

Thanks, I’ll check that out.