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???
04/25/07 22:40
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 		 #137958 - What is in my mind...
Responding to: ???'s previous message
Yes .Richard's advice is useful even during the operation and software changing the main frequency but it is more than I need.although because the idea of using two independent oscilator it is useful for me too.
I need to select afrequency before startup which remains permanent during operation so it wont change but why not just a simple socket?? here is the reason if you like to know ,but you can ignore it if you are not interested .it is long enough that I can give it to my english teacher as a writing!!!
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I have designed a board to make prototyping easy,like commercial ones which you know it has a few necessaey features,a regulated voltage,ZIF socket,buffer and connector for ISP programming,...
and also RS-232 converter ,which I use it not only for likely usage in some projects but also for programming USART ISP MCUs like XX89C51RD2... to prevent problems when I need to program these kind of ICs and thoese projects I need precise common baude rate in them, I decided to have a 11.0592MHz(for example) permanently assembled in my board . But what if I need other frequencies (especially 1MHz products)? As you (Erik) suggest I put a socket (not a second crystal) which may be any frequency. and I put a switch which enables me to select one of them ,this way even if there is no crystal in that socket(or proper one for programing ED2s or RD2s) I still can program my MCUs using SPI or USART in system programming. in addition if 11.0592 is satisfactory I can continue...
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Koosha


List of 31 messages in thread
TopicAuthorDate
two crystals            01/01/70 00:00      
   Crystal connections            01/01/70 00:00      
      wires very very short            01/01/70 00:00      
         Youd be better off with a pair of DIY oscillators            01/01/70 00:00      
            why not use a derivative with a PLL?            01/01/70 00:00      
               What's a PPL?            01/01/70 00:00      
                  Phase Locked Loop            01/01/70 00:00      
                     It's not a very general sort of PLL            01/01/70 00:00      
                        apples and oranges            01/01/70 00:00      
                           Consider why one would want that ...            01/01/70 00:00      
                        PLL lock timing            01/01/70 00:00      
                           support droids didn't notice that ...            01/01/70 00:00      
                              .. err make that "jibe" : -)            01/01/70 00:00      
                     Atmel MCU with PLL?            01/01/70 00:00      
                        sometimes two wants do not jive            01/01/70 00:00      
                        sadly atmel 8051 derivatives dont            01/01/70 00:00      
            Am I right Richard?            01/01/70 00:00      
               What I meant ...            01/01/70 00:00      
   Koosha, we need an answer            01/01/70 00:00      
      What is in my mind...            01/01/70 00:00      
         why a switch ? It will give you all kins of proble            01/01/70 00:00      
         Maybe use a jumper instead of a switch?            01/01/70 00:00      
            better, yes, as good as none no.            01/01/70 00:00      
            it's commonly used.            01/01/70 00:00      
               all the story!            01/01/70 00:00      
                  Capacitor size            01/01/70 00:00      
                  whare is the uC?            01/01/70 00:00      
                     The uC is in the ZIF socket            01/01/70 00:00      
                  not this type of switch, please            01/01/70 00:00      
                  consider ALL the components!            01/01/70 00:00      
   Thank you!            01/01/70 00:00      

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