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Using MOD5234 external DTxIN signal for external UART clock
Posted: Thu Jun 17, 2010 2:22 pm
by cbyrne
We have a question regarding use of a crystal oscillator as the clock source. We will supplying a external clock input to UART1 to support a 312500 baud rate SO we'll need a 5MHz clock. I'm concerned about the type of clock and characteristics of such clock with respect to the DTxIN requirements and overall capacitance as relatively long traces (2 inches) as we route the clock from our carrier board through the 50 pin MOD5234 header to the MPU. Any impedance or signal issues noticed?
Re: Using MOD5234 external DTxIN signal for external UART clock
Posted: Thu Jun 17, 2010 11:14 pm
by rnixon
Why does your oscillator need to be 2 inches away from the module? Not really enough information here to give a good opinion. There must be other constraints you are not providing, otherwise it would seem that there would be no problem. For example, what does the freescale processor manual say about the maximum input frequency? 5Mhz doesn't seem that fast for this part. Why do you think there would be a problem?
Re: Using MOD5234 external DTxIN signal for external UART clock
Posted: Fri Jun 18, 2010 7:51 am
by pbreed
Use good grounds put 50 ohms or so in series and at 5Mhz this should not be an issues at all.
Paul