#9604 NORM 1.5-sof: build DC sensor mode on audio driver
Zarro Boogs per Child
bugtracker at laptop.org
Tue Dec 8 03:31:04 EST 2009
#9604: build DC sensor mode on audio driver
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Reporter: Quozl | Owner: dsd
Type: defect | Status: new
Priority: normal | Milestone: 1.5-software-beta
Component: kernel | Version: not specified
Resolution: | Keywords:
Next_action: diagnose | Verified: 0
Deployment_affected: | Blockedby:
Blocking: |
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Comment(by Quozl):
Reviewed schematics, pg 20, AUDIO_CODEC.
* the resistance value I deduced matches the series resistance of R9 (470
ohms) and R7 (3k4).
* the emitted voltage values match what should be seen when signal B_BIAS
raised during ''arecord'', and returned low when ''arecord'' stops.
* B_BIAS is also being raised for a short time when the master volume
control is muted or unmuted.
Reviewed Measure source code changes made for XO-1.5 support, using
repository
git://git.sugarlabs.org/measure/XO_1_5_support.git
* there was no change to the method by which samples are read from the
sound device,
* there were some minor changes around setting mixer values.
Reviewed Measure interface to audio hardware;
* it uses gstreamer to read audio samples,
* apart from manipulating mixer settings Measure does not change how it
captures samples when in DC mode.
Therefore my use of ''arecord'' for analysis of the system at kernel and
hardware level is reasonable, and I can continue to use that method.
Summary: on os51, in DC mode, DC samples are unchanging despite input
voltage being changed. It is as if the analog voltage is not reaching the
kernel. I can't see any way they wouldn't be reaching the codec, given
that AC samples certainly do.
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Ticket URL: <http://dev.laptop.org/ticket/9604#comment:14>
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