"OverClocking" m644/m168 for avr-usb / 3.3V

Go To Last Post
6 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I'd like to use avr-usb on a 3.3 project, but these two megas are quoted at <= 10Mhz at 3.3V.
Has anyone tried it ? Would you think I could push it to 12Mhz ?

The idea is to use a one-cell LIION for "unplugged" operation and have USB to 1) recharge the battery 2) talk to the computer...

Author of simavr - Follow me on twitter : @buserror

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

As always, if this is your project then do whatever works. If you are going to sell it then stay within specs.

Consider this design change: Spend the extra US$5, add FT232R, run the logic side at the battery voltage, and still use the USB to charge the battery.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Check page 306. 12 Mhz is still in spec at 3.3V

10Mhz is for 2.7V.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

buserror wrote:
Would you think I could push it to 12Mhz ?

I've given advice on this subject matter many, many times...

In a word, DON'T !

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:

I've given advice on this subject matter many, many times...

In a word, DON'T !

Carl,

He is NOT overclocking running at 12 Mhz on a 3.3V supply.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Actualy, I'd have to slap myself, hard. CirMicro is dead right. The 644 datasheet page 359 states it will do 20 Mhz from 2.7 to 5.5! Of course thats wrong :D

The curve page 318 shows the frequency progression, and 2.7 = 10Mhz and gradualy goes to 20Mhz at 4.5V, so I should rather comfortably do 12mhz at 3.3.

Best way to know is to try it, next :D

Author of simavr - Follow me on twitter : @buserror