jadonk / beagleboard

Automatically exported from code.google.com/p/beagleboard
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C70 removal and GPTimer1 issue. #35

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago
I have a B5 board that has C70 removed. This was stated to improve 32khz 
rise/fall times and corrects GPTimer1 issue. My testing shows that GPT1 
stills does not function as expected when clocked from the 32khz source. I 
know the workaround to clock timer module from system clock. I was able to 
use the secure 32khz GPTimer12 to clock my test code and it works as 
expected. When the same exact test code is switched to GPTimer1 it 
triggers erratically. I suspect that removing the 100pf C70 cap may have 
help things in the lockup area but we may be getting extra edges now. I am 
guessing, but I suspect maybe a 22pf or the like might be an optimum 
solution. I have not actually probed the signal with a scope but I would 
suspect that just the probes capacitance may also be enough to cool down 
the signal and may mask the actual problem. There may be something else 
going on, including my understanding of the timer module itself but this 
is my best guess.

Original issue reported on code.google.com by dvdvesco...@gmail.com on 13 Oct 2008 at 3:31

GoogleCodeExporter commented 9 years ago
After further investigation this does not seem to be a real issue.
It was my understanding of timer operation (was not using posted mode ..tech 
manual
was not that clear) that was at fault. GPTIMER1 working as designed now.

Original comment by dvdvesco...@gmail.com on 20 Nov 2008 at 1:27

GoogleCodeExporter commented 9 years ago
User confirmed this was not an issue.  Tech manual was unclear.

Original comment by jdk%ieee...@gtempaccount.com on 1 Dec 2008 at 5:19