On 2015-07-30 12:36 AM, TJ Campie wrote: > Joe, You are correct when the input device has been enumerated as a > microphone input, which is the bug.
No, enumerating the device as a microphone input is *not a bug* when the device descriptor specifically identifies the input as microphone. If the designer is using the PCM290x device in a "line in" deign, he should be using the PCM290xC (or current equivalent) which identifies the input terminal as 0x603 (Line connector) instead of the PCM290xB which identifies as microphone. 73, ... Joe, W4TV On 2015-07-30 12:36 AM, TJ Campie wrote:
Joe, You are correct when the input device has been enumerated as a microphone input, which is the bug. Without "clearing" the bug forcing windows to enumerate it as a line in device, 100 on the slider is indeed adding gain. However after clearing the bug, it's now enumerated as a line in device and 100 on the slider is 0db, even if it reads +30 (the UI and dialogue box still thinks this is a microphone input device, this is part of the bug). This was verified by feeding a reference signal of a known level into the chip and obtaining a known output level, confirming 100 on the slider is indeed 0db of gain/attenuation AFTER clearing the bug. This behaviour is confirmed by TI themselves in this whitepaper: http://www.ti.com/lit/an/sbfa020/sbfa020.pdf If you have a signal generator I highly recommend feeding a reference level signal into a device using the chip and measuring the output yourself AFTER clearing the bug. Remember, you are correct that the slider value will add gain when it's been incorrectly enumerated as a microphone device. Measure a reference input signal AFTER clearing it. Hope that helps the confusion 73 TJ W0EA
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