http://rhombus-tech.net/community_ideas/kde_tablet/news/
i got the ADC operational.
also as anyone on the #arm-netbooks irc will notice i've done a reorganisation of the kde tablet news page, so each entry has its own page that is available for discussion. for example here: http://rhombus-tech.net/community_ideas/kde_tablet/news/2nd_revision_adc_ope...
also there's an RSS feed - i liked the idea and threw it out there: http://rhombus-tech.net/community_ideas/kde_tablet/news/index.rss
l.
ok, i gave up on using PWM for the speakers, and decided to use the 12-bit DACs instead. the voltage in on the TDA2822D looks to be around 0.06V and that gives approximately a 2V swing on a 5V rail. i'll experiment a bit more, try to find a random 470uF capacitor for use on the output (i'm only using 100uF at the moment), this should give a larger output range.
... it's getting there.
l.
http://rhombus-tech.net/community_ideas/kde_tablet/news/2nd_revision_dac_aud...
quick video demo there as well. irony is that in fixing the dynamic range (200k - 2.4k resistor bridge) i might have found out what the problem with the PWM circuit was as well: overload of theTDA2822D. however, after putting the scope on the output from PWM even after quite a lot of RC filters i really don't want to chance it. 12-bit DAC on an 8mm x 18mm 0.5 watt speaker is... enough :)
l.
arm-netbook@lists.phcomp.co.uk
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luke.leighton