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Topic: Atmega1284P @ 16MHz with 3.3V? (Read 2 times) previous topic - next topic

Grumpy_Mike


I've run ATmega328's @ 16MHz @ 3.3V. One is connected to a nRF24L01 wireless module and a couple of I2C sensors. Have not had any issues.  

So have you tested this over the full temperature range, over the full voltage tolerance range. Have you tested the voltage thresholds of the inputs, the voltage outputs and loading. The propagation delays and all the machine op codes? How many samples have you tested?

No I thought not.

A simple functional test tells you absolutely nothing but yet beginners often think it is the be all and end all. It is not.

Bajdi

For hobby stuff I see no reason to not try it. A crystal is easily swapped if it doesn't work. The downside is that when you run in to trouble you will keep guessing if it's the mcu that is acting strange or if your code is buggy. If I would make a commercial device I would stick to what the datasheet says.
Some people have no problem in selling boards that don't meet the specifications. I've seen a Chinese Arduino clone which has a jumper to switch between 3.3V and 5V and has a 16MHz crystal.
When I was a student I spent most of my free time overclocking cpu's using a LN2 setup just to see what the max frequency was. Some cpu's it was possible to run them at 1.5-2x the rated clock frequency, would only work for a couple of minutes though :p 
When I last ordered some 16MHz crystals from Tayda I saw that they also sell 25MHz crystals so I couldn't resist and bought some  :P
 

pico


So have you tested this over the full temperature range, over the full voltage tolerance range. Have you tested the voltage thresholds of the inputs, the voltage outputs and loading. The propagation delays and all the machine op codes? How many samples have you tested?

Yawn ;)
WiFi shields/Yun too expensive? Embeddedcoolness.com is now selling the RFXduino nRF24L01+ <-> TCP/IP Linux gateway: Simpler, more affordable, and even more powerful wireless Internet connectivity for *all* your Arduino projects! (nRF24L01+ shield and dev board kits available too.)

dhenry

Quote
For hobby stuff...


Some among us like to fancy themselves as designers for NASA.

JoeO

If all you are going to be doing is to flash an LED on the Arduino board, then you can get by going out of spec.  Who knows or cares if it misses a flash or hangs up and does not work.  But if you are doing something serious like making an alarm system, replacing a controller for your dish washer or building a keypad to open your garage door, then you need to be exact and operate within the specs of all the parts you are using. 
It is easier to do it right the first time than to figure out what is wrong.

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