On Wed, Jun 15, 2016 at 09:14:39AM -0700, Clark Dunson wrote:
Hello Charles, Peter, and Mark
Another progress report, some feedback, and a question.
We have everything pretty much working now.
The clocking configuration I identified in an earlier post, (ie. MCLK1 begin fed from BBB McASP0 24.576 MHz, and BCLK being derived from it) works, though we still have a patch to arizona-core.c to make it so. Ready for any inputs on how we can make this change so we can upstream it.
This week is very busy for me let me put together some stuff and get back to you next week on this one. I have some changes that add the stuff required but it probably needs to be reshuffled so we can get it upstream in a reasonable time frame.
Selecting single-ended mode vs. differential mode being a pairwise choice (ie. one selection for IN1, not independently for L/R), caught us by surprise and required a harrowing ECO. (This selection appears to also not be supported by the driver) In the end we had to abandon single-ended mode, as
The wlf,inmode device tree entry lets you select between differencial and single ended.
the PGA acted in a manner that defied our understanding. To wit: If we had a signal connected to IN2LP, (AC through 1uF capacitor), then what we did with IN2LN was pivotal. If we connected I2LN to ground, the signal would have large positive offsets, eg. +0.5 on WAV scale of 1.0 to +1.0, with unity gain set on PGA, Digital Volume, and mixer. Cranking the PGA gain would rail the signal in a positive direction before we had adequate gain. If we left IN2LN floating, we got closer to zero-centered, but when we set PGA to +6dB, we got huge negative offsets (-0.6 on WAV scale) and still we were dead in the water. Finally we connected a 1uF capacitor to 1N2LN, and set back to differential mode (default). Life is better now.
Alas I am afraid you have exceeded my understanding of electronics here, you would need to discuss this with one of our hardware FAEs. I do know we have used both single ended and differencial in the past, but I am at a loss to explain what you are seeing there.
In our status meeting yesterday, we concluded that our moving forward with thousands of units would be benefited both on our side and Wolfson’s by an FAE as a go between. Is your Cupertino office still alive (we are in Bay area), or can we get a point of contact? Is it Joao?
Yes Joao is probably a good place to start, and we do still have the Cupertino office.
Thanks, Charles