customer said:I think I’m seeing the clock speed up on the MSP430F5438A as much as 8%. This is affecting our serial communication using a UART and causing us to drop a byte. We are using a 32.768 kHz crystal and using the DCO with a multiplier of 512 to get it to 16.777216 MHz. I was hoping you could suggest some causes for the clock rate changing. What can I look at?
The MSP430F5438A uses a Unified Clock System (UCS) module.
MSP430F543xA, MSP430F541xA Mixed Signal Microcontroller (Rev. B) (PDF 1016 KB) 15 Oct 2010
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How have you sourced these clocks?
Auxiliary clock (ACLK)
a 32-kHz watch crystal
a high-frequency crystal
the internal low-frequency oscillator (VLO)
the trimmed low-frequency oscillator (REFO)
or the internal digitally controlled oscillator DCO
Main clock (MCLK)
a 32-kHz watch crystal
a high-frequency crystal
the internal low-frequency oscillator (VLO)
the trimmed low-frequency oscillator (REFO)
or the internal digitally controlled oscillator DCO
Sub-Main clock (SMCLK)
a 32-kHz watch crystal
a high-frequency crystal
the internal low-frequency oscillator (VLO)
the trimmed low-frequency oscillator (REFO)
or the internal digitally controlled oscillator DCO
How have you set UCSSELx in the USCI_Ax Control Register 1 (UCAxCTL1)?
MSP430x5xx/MSP430x6xx Family User's Guide (Rev. J)
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