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9S08QE128 baud rate to 115200?

Question asked by GARY OLMSTEAD on Feb 3, 2020
Latest reply on Feb 4, 2020 by GARY OLMSTEAD

Hi --

 

I am using a 9S08QE128, (internal clock oscillator, FEI mode), and have to tie it to a Bluetooth module that has a fixed baud rate of 115200.  I can get there with the QE128 by setting the internal oscillator to 36kHz, bus freq divide by 1, internal bus clock to 9.216MHz, and setting the DCO mode to "default 512", instead of "fine tuned 32kHz".

 

My question is, what does not selecting fine tuned mode do to the oscillator accuracy?  The data sheet talks about "user trimmed" reference frequency, but we don't really have the resources to do that in production quantities.  What is the accuracy if I use it as it comes from the factory?

 

Gary Olmstead

Ventura CA

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