Questions about the Atmega MCU

[CyRuS]

Greetings from Italy! I would like to build a megadrum digital board, just to see if it works. I can make for myself the PCB and I also have the other components, but I miss the Atmega324P because I can't find this device in local stores. I have found this on ebay
http://cgi.ebay.it/AVR-Atmel-Atmega32-A ... 286.c0.m14

can I use that instead of the 324P version? I've read on the migration datasheet that there are some differencese between the two models, but what could be the differences on a Megadrum built with an Atmega32 and one built with an Atmega324P? thank you for future answers and sorry for my not quite correct english

[Firelord]

If that's ATMega32 in a PDIP40 package then of course you can use it with the current MegaDrum 32 input design. The difference is that you need a 16MHz crystal for it (in case of ATMega324P you need a 20MHz crystal) and you should use firmware for ATMega32.

[dmitri]

http://it.farnell.com/atmel/atmega324p- ... dp/1455110
http://it.farnell.com/atmel/atmega644-2 ... dp/1288340

[CyRuS]

well 32 inputs are enough for me, I think I'll buy that. yes, farnel sells all it is needed for megadrum but I don't want to pay more than the double of the price of the ATmega, so I think I'll buy it from ebay. thanks for the answers

[dmitri]

Farnell does free delivery on orders above £20 here in the UK so I guess it is something like 25 Euros in Italy, so if you in fact buy a few things from Farnell, Atmega324P will turn out to be cheaper then Atmega32 from ebay.

[Ale.A]

This one is ok, using a 16MHz crystal and it has the same input of atmega324p,so same board, right?

By the wat, sorry for OT, the 20MHz crystal it's not exactly 20, it's 20.48 Is it a problem? link

[Firelord]

This one is ok, using a 16MHz crystal and it has the same input of atmega324p,so same board, right?

It looks ok, but it should be in a PDIP40 package (if the picture is correct then it is). It will work with a 16MHz crystal.

[dmitri]

By the wat, sorry for OT, the 20MHz crystal it's not exactly 20, it's 20.48 Is it a problem?

It must be 20MHz exactly.

[Ale.A]

Being born in Italy is a pleasure for me too.. but they don't think the same of our Mail service... so they don't sell in italy
This should go or just look for ATmega32-16pu

Thanks for the crystal, This should go

[CyRuS]

I have another question, but this one insn't about the MCUs: how can I connect a single piezo to test the digital board without building an entire analogue board? I want to be sure that the first is working before spend time and money to make the second