At 20.56 2005.05.16 +0200, you wrote:
>> >First, a 40MHz PIC only runs at 10MIPS, which isn't too 
>> fast.. So, maybe use 
>> >an external data buffer between the two devices might help?? 
>> Or using a 
>> >custom FPGA in place of a PIC?? It all depends on how you're 
>> interfacing with 
>> >this 44.5MHz device..
>> 
>> No, the problem is economy: there are millions elegant
>> solutions to a problem, but when you want the best bang
>> for the buck, there's at most one solution..
>
>Just be carefull to calculate your bang and buck appropriately. For
>instance: don't forget
>- engineering cost
>- all costs of product failures (replacement, customer goodwill lost)
>
>In this case I would say: Why not select something (dsPIC, ARM, ...)
>than is guaranteed to run at 44.5 MHz?

Yes, but I already have these hundreds 40MHz parts and hundreds
11.059200 MHz XTALs. ;P Also, the application has a RS232 interface,
so I like this XTAL frequency a lot (it is 115200*96..).

I have also hundreds dsPICs and I would use them, the /3 prescaler
on their PLL is a wonderful thing.. I could get 29.4912 MHz core
speed (i.e. very near to the specced 30MHz) if the PLL could do x32
instead of being limited to a max x16. I guess I'm not too lucky..
The datasheet already left no hope, anyway: is there a way to make
run the dsPIC core at more than Fosc/4?

Of course I could use an external PLL, but that would probably cost
more than the MPU itself.. so what's the point? as I said above "the
problem is economy: there are millions elegant solutions to a problem,
but when you want the best bang for the buck, there's at most one
solution..".


>Wouter van Ooijen

 
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