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Erik Malund
02/18/08 14:05
Read: 863 times
Mt Airy, Nc

#151055 - I wonder
Responding to: Richard Erlacher's previous message
Locking one's timing to a specific baud-rate generator crystal can prove a serious disadvantage under some circumstances, e.g. this case. It is not unsolvable with the "old, tried-and-true" crystal but if it's convenient, why not try, say, 24 MHz? You can get "close enough" to low standard baud rates with that.
using T1 you can go no higher than 4800 (and T2 is soooo useful for other stuff) of course, if you can spare T2 you can get to 28k, but that I will even consider 'low'

Aside from that, dividing 11059200 by 49152 in a 16-bit counter leaves a divide-by-225 to generate 1 second.
I wonder how you are going to fit 11059200 in 16 bits :)

Anyhow, i wonder what 'lack of precision' any decent crystal frequency will give at 1-30 seconds.

Yes, Richard a 'baudrate crystal' is not always the right choice, but most often it is.

As an example using USB I am forced to clock at 12MHz, and I have to multiply that up to 48MHz (the chip has a PLL) to get a decent T2 baudrate.


List of 10 messages in thread
11.059Mhz clock to create 1-30 second delay in C?      Chris Bertrand      02/17/08 18:20      
   as far as I remember...      Jose Orlando T. Ribeiro      02/17/08 18:34      
      It's worse than that, Jim      Andy Neil      02/18/08 00:21      
   solution?      Russell Bull      02/17/08 23:13      
   Not nested loops!      Andy Neil      02/18/08 00:03      
      I'll check those out tonight after work      Chris Bertrand      02/18/08 05:12      
         delay needs to be centered around 5 seconds or so      Andy Neil      02/18/08 05:38      
            Samuel Clemens said      Erik Malund      02/18/08 09:47      
               Couldn\'t use of a different crystal solve this?      Richard Erlacher      02/18/08 13:03      
                  I wonder      Erik Malund      02/18/08 14:05      

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