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Per Westermark
12/19/10 04:30
Read: 1502 times
Sweden


 
Msg Score: +1
 +1 Good Answer/Helpful
#180211 - Overclocking
Responding to: Erik Malund's previous message
I bet most (all) chips can do 30MHz.

But a very important aspect is that Atmel specifies 20MHz. And that is a frequency that Atmel claims is safe within a specified voltage range and within a specified temperature range.

Most chips can be run at a higher clock frequency if slightly overvolted. But have you tried running the AVR chip at lowest specified voltage? Have you tried it at highest allowed temperature where the internal temperature from the chip will add more heat than the test conditions Atmel used?

30MHz with the chip is something you can play with on your desktop at home/office, when the chip is powered with a laboratory power supply. Not something you can rely on when the chip is in a vehicle or other environments where you don't have control over the temperature or the amount of noise on the power lines.

The reason lots of hobbyists can overclock their PC machines is that they can - to some extent - control the environment stricter than the general test conditions the chip/motherboard/PC manufacturer may require. Using a 1kg cu HSF or maybe water cooling means you can push a chip further.

But an important aspect is that even if you do control the environment and get a pushed chip to run stable, there's a second thing to remember. Excessive heat or excessive currents, through some critical paths on the chip may significantly affect the ageing process. It is well known that overclocked PC processors may run stable for months or years before suddenly starting to hang. The owner must then step-by-step reduce the voltage/frequency just to maintain stability - sometimes the overclocked chip starts to require lower speeds than the specification says, just to behave. Just because of degrading of the chip.

So it's very important to separate what is ok to do for a hobbyist, and what is ok to do for commercial projects. A hobbyist may break things but will only hurt himself. And the hobbyist is expected to understand that the probability of failure will be higher when pushing things past recommended limits.

If a manufacturer have said that clock speed X will be released in Q2, then a commercial company may decide to work with overclocked chips in Q1 just to be able to test source code and learn the timing implications of running at a higher speed. As long as they don't ship the overclocked product, or assume that they can compute reliability figures from the overclocked product. A manufacturer that has a roadmap with multiple speeds may release the higher speed after having tested a longer time just to make sure. Or they may have binned chips before having enough chips to sell. Or they may have needed to stricted up the manufacturing process to get less variances. Or they may have had to redesign critical parts of the circuit after careful analysis. But a customer doesn't know, and can't rely on such things. Maybe, just maybe, the manufacturer just binned chips and the customer did receive a chip that should have been binned as faster. Maybe.

List of 103 messages in thread
TopicAuthorDate
Migrating to AVR      Jason Arkwright      12/06/10 10:02      
   8051-replacement      Andy Neil      12/06/10 11:37      
      Yep, I agree      Jason Arkwright      12/06/10 13:47      
         Toolchain      Andy Neil      12/06/10 14:41      
            free compilers      Jason Arkwright      12/06/10 15:32      
               GCC      Andy Neil      12/07/10 00:24      
               Free ARM compilers      Oliver Sedlacek      12/07/10 07:14      
                  "Free" vs "Free"      Andy Neil      12/07/10 07:54      
   faster '51 derivatives in DIL/PLCC & availability      Jan Waclawek      12/06/10 13:26      
      Tired of hanging around with 5 mips      Jason Arkwright      12/06/10 14:04      
         Re: Tired of hanging around with 5 Mips      Valentin Angelovski      12/06/10 17:59      
            experiences prototyping with smd's      Andy Neil      12/07/10 00:09      
               Prototype SMD      Oliver Sedlacek      12/07/10 09:24      
            Nice, but where to buy and how much?      Jason Arkwright      12/07/10 04:57      
               Re: where to buy and how much?      Valentin Angelovski      12/07/10 07:48      
                  Yeah, but....      Jason Arkwright      12/07/10 08:36      
                     I agree      Valentin Angelovski      12/07/10 17:11      
                        re the XA      Erik Malund      12/08/10 06:39      
                     How many 51' compilers make use of the 51's dual DPTR      Andy Neil      12/07/10 17:54      
               You must live on a very interesting corner!      Andy Neil      12/07/10 07:55      
                  Ha,ha, AVR are ubiquitus      Jason Arkwright      12/07/10 08:22      
                     HUH??      Erik Malund      12/07/10 08:36      
                        Lies, Damned Lies, and Statistics      Andy Neil      12/07/10 09:08      
                           I think      Erik Malund      12/07/10 12:01      
                        'F120      Andy Peters      12/07/10 10:36      
                           "bunchload"      Andy Neil      12/07/10 11:35      
                              re: bunchload      Andy Peters      12/08/10 09:28      
                                 Youse guys in Old Blightly        Andy Neil      12/08/10 10:04      
         Prototyping SMD's      John D. Maniraj      12/07/10 00:58      
            Hand-made PCBs with hand-soldered SMDs      Andy Neil      05/04/11 08:30      
            SMD's      Jerry Hudson      05/08/11 09:24      
               Well, that's nice, but not necessary.      Richard Erlacher      05/09/11 09:42      
            a very general - and accurate - comment ...      Erik Malund      05/11/11 07:14      
               apprehension      Andy Neil      05/11/11 07:33      
   nearby      JecksonS Ben      12/07/10 22:12      
      'jumping' from the '51      Erik Malund      12/08/10 06:52      
         AVR update      Jason Arkwright      12/18/10 07:43      
            the chip does not crash      Andy Neil      12/18/10 11:34      
               Lockup etc      Per Westermark      12/18/10 13:41      
                  increase the clock until lockup      Jason Arkwright      12/18/10 15:50      
                     undefined behaviour      Andy Neil      12/18/10 16:24      
                     NO, they do not recommend it      Erik Malund      12/18/10 16:27      
                        simultaneous posts      Erik Malund      12/18/10 16:28      
                           Overclocking        Per Westermark      12/19/10 04:30      
                     This is simply an error in judgment        Richard Erlacher      12/19/10 09:38      
                        all bets are off      Andy Neil      12/20/10 01:19      
                     overclocking        Andy Peters      12/22/10 09:27      
                        Yeah, okay      Jason Arkwright      12/22/10 10:31      
                           Neeed for speeed      Andy Neil      12/22/10 10:56      
                              Because of this...      Jason Arkwright      12/22/10 16:55      
                                 Missing the point      Andy Neil      12/22/10 17:16      
                                    missing the point?      Jason Arkwright      12/22/10 17:46      
                                       Modern derivatives      Andy Neil      12/23/10 01:02      
                                 hogwash      Erik Malund      12/22/10 18:22      
                                 I'm not sure you're on track here ...      Richard Erlacher      12/22/10 20:39      
                                    Hi Richard      Jason Arkwright      12/23/10 14:44      
                                       the problem with AVR's is that they're ATMEL only      Richard Erlacher      12/25/10 08:59      
                                          That's one general and one personal problem      Andy Neil      12/26/10 12:08      
                                             Yes, that's what it is ...      Richard Erlacher      12/26/10 19:29      
                                                Second source not so important anymore      Per Westermark      12/27/10 07:40      
                                                   It's not as convenient now as it once was      Richard Erlacher      12/27/10 08:01      
                                                      Free tools only have investment in knowledge      Per Westermark      12/27/10 08:29      
                                                         again. Per      Erik Malund      12/27/10 09:04      
                                                            Not at all      Per Westermark      12/27/10 09:46      
                                                         it's not just the tools      Richard Erlacher      12/27/10 14:44      
                                                            "Best code"        Per Westermark      12/28/10 05:56      
                                                               There are too many definitions of "best"      Richard Erlacher      12/28/10 15:47      
                                                               Don't go for best      Steve M. Taylor      01/03/11 08:50      
                                                   yes and no      Erik Malund      12/27/10 08:29      
                                                   Single-source chips vs single-source architecture      Andy Neil      12/27/10 10:23      
                                 cross purposes      Andy Peters      12/23/10 11:12      
                                    DSP PROCS      Jason Arkwright      12/23/10 14:25      
                                       gp ahead, stay behind the curve      Erik Malund      12/23/10 14:37      
                                          Got to disagree there,...      Jason Arkwright      01/02/11 15:55      
                                             I do not consider 'luck' a design parameter      Erik Malund      01/03/11 05:24      
                                             Flying leads      Valentin Angelovski      01/03/11 05:33      
                                       re: DSP PROCS        Andy Peters      12/27/10 10:48      
                           100MHz 32-bit ARM      Per Westermark      12/22/10 12:49      
                              The Trap...      Jason Arkwright      12/22/10 17:11      
                                 talking out of both sides of the mouth      Erik Malund      12/22/10 18:27      
                                 "on the DSP level"        Andy Neil      12/23/10 01:07      
                                    Often hand-optimized assembler available      Per Westermark      12/23/10 07:59      
                                    Misunderstood me      Jason Arkwright      12/23/10 16:14      
                                       Cross talk      Per Westermark      12/23/10 16:37      
                                       What kind      JecksonS Ben      12/23/10 18:19      
                                       nobody has suggested      Erik Malund      12/24/10 10:11      
                           no, you are not      Erik Malund      12/22/10 14:59      
                           there are '51s with MACs      Erik Malund      12/22/10 15:05      
                              and...      Andy Neil      12/22/10 16:21      
                                 yes and      Erik Malund      12/22/10 18:28      
                                 He wants Plastic Dips      Neil Kurzman      12/22/10 18:28      
                                    very few and      Erik Malund      12/22/10 18:33      
                                    the 33 mips DS89C450 is in DIP if you want      Richard Erlacher      12/22/10 20:42      
            no such thing as "Best"      Andy Neil      12/18/10 11:38      
               '51 weaknesses outweigh the AVR      Jason Arkwright      12/18/10 16:02      
                  similiar      JecksonS Ben      12/18/10 21:07      
                  Quite so      Andy Neil      12/19/10 08:59      
                     3, 4, 5        Michael Karas      12/20/10 08:25      
                        Horses for courses      Andy Neil      02/14/11 01:22      
                  Have you considered using a DSP?      Richard Erlacher      05/11/11 16:55      
   I'll be off too, but not to AVR      Oliver Sedlacek      02/14/11 03:31      
      A Guess      Michael Karas      05/04/11 18:54      
         Low volume      Oliver Sedlacek      05/05/11 06:25      

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