Re: ice1712 IPGA and ADC controls

[John Rigg <aldev@sound-man.co.uk>]

On Tue, Jan 30, 2007 at 06:18:38AM +0000, Tim wrote:
> There is no such thing as analog attenuation on these chips.
> Only an analog gain stage from 0db to +18, followed by a digital 
>  attenuation stage from 0db down to infinity (mute).
> Both of these functions are accessed through the same register,
>  as a continous range from 0 to 164. The first 127 steps
>  'activate' the digital attenuator, with 127 being 0db, while the
>  last 37 steps 'activate' the analog gain.
> In other words, from 0-127 ONLY the digital attenuation stage is
>  activated. From 128 to 164, ONLY the analog gain stage is activated.
> It was intended to be one control.

That makes sense (thanks for the clarification). I think it's
important to clearly mark the 0dB point, and also to make 0dB
the default setting.

> Anyways, I say we add some type of 'decorations' to envy24control.
> Some type of markings. Two end-to-end 'braces' along the side spanning the 
>  length of sliders, one labeled "digital att." meaning that the range from 
>  0-127 is digital attenuation, and the other labeled "analog gain" meaning 
>  the range 127-164 is analog gain. It would be a great visual reminder of 
>  this underlying technical detail we have discussed here, so everyone  
>  should understand it.

Good idea.

> And of course all values in db's as well as integers.

dB would be nice.

John

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