AVR-Chat

Jay Dagenais wrote:

> Whoops, clumsy thumb, anyways, long story short,all I need to know is
> programming the ATtiny45 from the STK300 dev board is possible. All I've
> done is taken out the dev boards chip(ATMega103L) and placed jumpers
> from the proper headers over to the breadboard with the tiny45. The
> STK300 uses just basic hardware for programming, it is a few resistors
> and a 4053 IC after the ISP dongle. I have already tried but it didn't
> work yet, but I think the issue is actually with the dongle and its
> commonly known issues, so I am in the process of fashioning a new dongle
> now. In the meantime, I need to know if this is a good way to integrate
> ISP function into my final board layout?

Another possibility is to consider using DebugWire (their 1-wire 
protocol), but that requires a more expensive progammer. Depending on 
how you've configured your circuit, you may not need something as 
complex as a mux. For instance, if you've got analog inputs, a series 
resistor between a buffer and the microcontroller input may be enough. 
And outputs that aren't heavily loaded may be OK by themselves. Another 
possibility is a jumper field, with removable jumpers on those lines 
that can't be disconnected from low-impedance inputs.

There are only 4 pins that you have to worry about:

/RESET -- need to pull this low to start programming. A simple pull-up 
resistor should be adequate (and there's one in the chip anyway). If you 
can leave this pin alone (i.e. if you don't need it for other purposes) 
you can just connect it to the ISP pin.

And you should make sure that these three pins aren't so heavily loaded 
that the programmer or micro can't drive them (for instance, if you've 
tied the output of an op amp directly to one of the pins, you'd have to 
have some way to isolate it).

MISO -- PB1 -- output from the micro.

MOSI -- PB0 -- input to the micro.

SCK -- PB2 -- input to the micro.

> and also what and how I can use
> AVRISP software to load (my version doesn't support tiny45, but maybe
> the newer versions do??) and if there are better software programs
> available for my purpose? Thanks in advance, jaydag71 

AVRDude supports the Tiny45. And it supports the AVRISP programmer. 
Though I haven't tried the two together.

Dunno about the STK300, but if it's just a mux it should work too.


Enjoy,
-- 
Ned Konz
ned@bike-nomad.com
http://bike-nomad.com