[alsa-devel] USB asynchronous mode feedback format
zonque at gmail.com
Thu Oct 14 18:11:23 CEST 2010
On Thu, Oct 14, 2010 at 05:54:35PM +0200, Julian Scheel wrote:
> Am Donnerstag, 14. Oktober 2010, 17:39:13 schrieb Daniel Mack:
> > What about the voltage levels? Are they within the specs? I had a quick
> > look and it seems that Vdd on the codec has to be within 3.0 .. 3.6V,
> > while the signals you provide rather seem to be in the range of 5V? The
> > absolute maximum ratings say that Vdd must not be greater than 4.0V.
> This might indeed be an issue. The clock signals have about 5V level... The
> data coming from the uC still has 4.2V
> This might be too much... Stays the question how to lower the voltage properly
> there... Any suggestions?
This get more and more off-topic for the ALSA community, but ...
For the signals, use a voltage shifter, something like the 74LVC2T45.
For Vdd, if you have to provide that to the board, use a proper
switching power regulator with low ripple, or an LDO, and care well for
Also check whether the voltages you applied all the time could have
damaged the chip permanently.
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