some first impressions

Mitch Bradley wmb at
Thu Aug 16 14:25:25 EDT 2007

Yoshiki Ohshima wrote:
>   Arjun,
>> 1) eToys:
>> It would be very nice to have support for Analog Input in eToys.
>> You could use my code -
>> See
>> (getting samples)
>> and
>> (toggling between AC/DC modes and controlling bias voltage etc.)
>> Or I could easily provide you with a class that you could use. I could make functions in that class that could simply
>> return to you the required values. For example there could be a function that you could call to return avg voltage or
>> rms voltage, select between ac/dc modes, set bias_on, set
>> bias_off.....
>> Let me know if I can help in any way.
>   Thank you.  As I wrote on, what we
> would like to have is C functions.  Then, I can wrap them as Squeak
> primitives.  Probably I can just rip these functions from amixer, but
> if you can tell me which, that would be good!
This is the relevant excerpt from the reference cited above.  The 
correspondence between this and C code should be obvious (os.system() -> 
system()), and it also implicitly answers the second question too.

    def ac_dc(self, data=None):
            self.button1.set_label("Measure AC")
            os.system("amixer set 'Analog Input' unmute")
            os.system("amixer set 'Mic' 20%, 0% unmute captur")
            os.system("amixer set 'Capture' 0%, 0% unmute captur")
            os.system("amixer set 'Mic Boost (+20dB)' mute")
            self.button1.set_label("Measure DC")
            os.system("amixer set 'Analog Input' mute")
            os.system("amixer set 'Mic' 20%, 100% unmute captur")
            os.system("amixer set 'Capture' 100%, 100% unmute captur")
            os.system("amixer set 'Mic Boost (+20dB)' unmute")

    def bias(self, data=None):
            self.button2.set_label("Set bias on ")
            os.system("amixer set 'V_REFOUT Enable' mute")
            self.button2.set_label("Set Bias off")
            os.system("amixer set 'V_REFOUT Enable' unmute")

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