NCO/PWM jitter
sjev
Posts: 10
Hello,
I am using the following code to generate a frequency (copied from the counter application notes):
The problem is that I get a pretty bad jitter (+-2% of the period).
What did I do wrong? Didn't I read the manual carefully? Or shouldn't I buy the DLP-PROP module? My oscilloscope is not fast enough to measure the clock frequency.
Funny thing is that a pulse generator at a different cog (using waitcnt) produces a pulse with a jitter sychronous to the NCO. So, does my system clock jitter???
I am using the following code to generate a frequency (copied from the counter application notes):
PUB StartDOD ctra := %00100_000 << 23 + 1 << 9 + dod_pin frqa := $8_0000 dira[noparse][[/noparse]dod_pin] := 1 repeat
The problem is that I get a pretty bad jitter (+-2% of the period).
What did I do wrong? Didn't I read the manual carefully? Or shouldn't I buy the DLP-PROP module? My oscilloscope is not fast enough to measure the clock frequency.
Funny thing is that a pulse generator at a different cog (using waitcnt) produces a pulse with a jitter sychronous to the NCO. So, does my system clock jitter???
Comments
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It jitters!!!! Damn FTDI!
Tomorrow I'll test another chip at work ( yes, it's more than a hobby
Maybe a word of warning should be added to the DLP-PROP page. Unstable frequency in industrial control applications is a pretty serious issue.
Post Edited (sjev) : 4/3/2007 10:56:34 PM GMT
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'Necessity is the mother of invention'
I am building an inkjet printer prototype. It is just a simple research device, but the timings should be absolutely solid for a dozen of reasons.