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???
08/09/06 12:17
Modified:
  08/09/06 12:18
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 		 #121903 - that\'s impossible
Responding to: ???'s previous message
I am using the internal RC oscillator with 7.3728MHz. ... Now if I wish to create a pulse with frequency = 3.6864MHz/2 by complemeting a port in timer 0 interrupt service routine, what value should i reload the TH0 and TL0?.

there is no way you can do that.
entering an ISR usually takes 4 cycles (maybe in the LPC only 2 - look it up) and the return takes - again look it up - cycles. Thus it is patently impossible to create anything 1/2 oscillator by using an interrupt.

it's bible time

Erik

PS why the FAQ in the header, this is NOT 'frequently asked'

here are the links to "the bible"
Chapter 1
http://www.semiconductors.philips.com/acrobat/v...ARCH_1.pdf

chapter 2
http://www.semiconductors.philips.com/acrobat/v...UIDE_1.pdf


chapter 3
http://www.semiconductors.philips.com/acrobat/v...WARE_1.pdf





List of 31 messages in thread
TopicAuthorDate
FAQ: P89LPC9221            01/01/70 00:00      
   Code Architect            01/01/70 00:00      
   that\'s impossible            01/01/70 00:00      
      pin toggle            01/01/70 00:00      
         Sure, but that does not achieve 3.xx MHz            01/01/70 00:00      
            interrupt            01/01/70 00:00      
               that will not do it as I did show in my post            01/01/70 00:00      
                  mode 2            01/01/70 00:00      
                     slovakian math ?            01/01/70 00:00      
                  usermanual of 89LPC9xx insufficient            01/01/70 00:00      
                     please read the WHOLE thread            01/01/70 00:00      
                        Can timer mode 2 overcome interrupt overhead?            01/01/70 00:00      
                           with mode 2 the reload is automatic as \"the            01/01/70 00:00      
                     did you not read            01/01/70 00:00      
   Re: 50kHz output...            01/01/70 00:00      
   I eneterd a FAQ on this            01/01/70 00:00      
      Where? I can't see it            01/01/70 00:00      
         here            01/01/70 00:00      
            I think you misplaced it...            01/01/70 00:00      
               I placed the FAQ correctly but - shame on me - pl            01/01/70 00:00      
                  What is the fastest frequency of Timer Mode 2            01/01/70 00:00      
                     fastest output            01/01/70 00:00      
                        Couldn't Wait in Endless Loop            01/01/70 00:00      
                           NOOOOOOOOO            01/01/70 00:00      
                              Where should i CPL p0.5 then?            01/01/70 00:00      
                                 oooh, then it's impossible, of course            01/01/70 00:00      
                                    89LPC9221 i2c interface            01/01/70 00:00      
                                       I am against "sharing code" but it is there            01/01/70 00:00      
                                          I2C interface with 89LPC9221            01/01/70 00:00      
                                             what does CodeArchitect do ?            01/01/70 00:00      
                                             push-pull?            01/01/70 00:00      

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