I'm trying to do something that I thought would be simple. I've been using SigmaStudio and the ADAU1761 for several years and I thought I understood how everything works; it looks like I'm coming up short now. Consider a very simple example: a DC Input Entry whose output is tied directly to a GPIO. I'm using GPIO1 and I've set the GPIO Pin Control register and Serial Data/GPIO Pin Config registers accordingly (output set by DSP core no pullup & GPIO Enabled). My SigmaStudio project also reads serial digital audio from the input serial port (DAC_SDATA, BCLK, LRCLK) and I can verify that the program is working because I have a simple level detector in the signal path and I can very clearly see audio level. So I know the chip is booting and handling audio correctly. But there's nothing I can do to get GPIO1 to do anything in response to the DC Input Entry -- no matter what I set it to, the GPIO aways outputs a logic low.
Am I missing something obvious?