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MC9S08GB60 Clock Options for SCI Baud of 31.25K

Question asked by danielhembree on Dec 4, 2012
Latest reply on Dec 11, 2012 by danielhembree

I am using an MC9S08GB60 as part of a system that will communicate to external devices via the SCI at 31.25K baud rate. The development board I have has a 32.768 external crystal. The code I have written thus far is configuring the ICG for a 4.19MHz bus frequency in FEE mode. I took this section of code directly from the data sheet. I have noticed what appears to be quite a bit of jitter (instability) on the SCI bit stream, and consequently, many communication errors with my receiving device. The question(s) I have are 1) Is there a more accurate clock scheme (such as FBE mode), and 2) can I get to 4.19MHz bus frequency using the external crystal in FBE mode. The information I have found covering the ICG is not completely intuitive, and my attempts to use FBE mode have been unsuccessful.

 

Also, is there something else that could be causing the instability withe the SCI bitstream?

 

Thanks in advance.

 

Dan

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