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PWM accuracy on MSP430G2553

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I'm working on a project where I need to oscillate at 25khz.  I've been using the PWM built into the MSP430G2553 and it doesn't seem to be accurate enough to give me exactly 25khz.  I've been getting anywhere from 23khz to 27khz and cannot figure out why it's off by so much.  I might be doing something wrong.  Does anybody know what sort of accuracy I should expect from the on board PWM in the MSP430G2553.  Is there a way to make it more accurate?  I was looking at adding an external crystal, but would rather not add that complication if it isn't necessary.


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You may want to take a look at page 29 and 30 of the 2553 datasheet which characterizes the DCO.  The DCO is not particularly accurate and my guess is that you will need the crystal to get the accuracy you are looking for as well as better consistency from device to device.

EDIT:  forgot the link to the datasheet  :)     http://www.ti.com/lit/ds/symlink/msp430g2553.pdf


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