Best practice incorporating microcontrollers into stompboxes?

[soggybag]

What's the best practice when incorporating a microcontroller into a stompbox? The question seems like it could be divided into 2 categories hard ware and software.

When it comes to hardware, what about the power supplies. I'm using a 78L05 type regulator with a couple caps. Is there any other special precautions?

What about unused pins? Should these be grounded or left un-connected?

What about the ground connection coming from the microcontroller? Does this need any special treatment, filter caps? I'm using an AVR attiny13.

Are there any software issues that need to be taken care of when planning a microcontroller for a stompbox? Can you be reasonable assured that a simple program will run for ever when connected to a battery?

Should I use any special settings for unused pins? Should they be set as in put, or outputs, or? 

[trendyironicname]

I don't have good info for you but how do you like the attiny13?

[The Tone God]

When it comes to hardware, what about the power supplies. I'm using a 78L05 type regulator with a couple caps. Is there any other special precautions?

This is covered again on my site where there is a power supply article.

What about unused pins? Should these be grounded or left un-connected?

What about the ground connection coming from the microcontroller? Does this need any special treatment, filter caps? I'm using an AVR attiny13.

Unused pins are typical set to input with no pull up then left unconnected. You don't want them set as output or input with pull up in case anything shorts to them. They can draw unnecessary current.

Digital and analog grounds should be kept seperate for their circuit portions then connect both sets of grounds to one point only like say the battery connection.

Are there any software issues that need to be taken care of when planning a microcontroller for a stompbox? Can you be reasonable assured that a simple program will run for ever when connected to a battery?

Depends on what your software is doing. Sometimes you will need things like watchdog timers and brownout voltage detectors other times you will want to put the controller to sleep to save the battery.

I like the Tiny13 for basic stuff. Once I need alittle more I grab something from the Tiny25/45/85 family. Recently I have really been enjoying the new 14 pin Tinyx4 family.

Andrew

[soggybag]

Andrew, your site is a one stop shopping spot for microcontrollers and more. I don't know how missed all this stuff.