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What am I doing wrong with TWR-SGTL-AUDIO, SCH-26816 REV B, why can't I seem to get LINEIN->DAP(Main)->DAC->LINEOUT working?

Question asked by Robert Thompson on Nov 25, 2013
Latest reply on Dec 12, 2013 by Carlos Neri

I've been on this for a couple of days. I have been handed TWR-ELEV pack, TWR-PROTO pack, and TWR-AUDIO-SGTL pack. I had a Teensy++ 2.0 laying around, it is using an AT90USB1286 (Atmel) processor. I am using the I2C interface as opposed the SPI.


TWR-AUDIO-SGTL, SCH-26816 REV B, does not have Y1 (24.576Mhz oscillator) loaded so I raided my work's store and got lucky with an oscillator I could set up in space free on the TWR-PROTO PCB with exactly that output - I did so and fed that output to CLK_MCLK via A21 on TWR-PROTO, it turned up on the correct pin of SGTL5000.


I've made all other connections and the CHIP_ID register returns as 0xA011 when I read it so PARTID appears correct as 0xA0 and REVID as 0x11 seems reasonable to me so I proceed; I set the registers as follows based on information in such gems as













I play audio from a source connected to LINE-IN jack and I listen on the (amplified) speakers connected to LINE-OUT and I listen on the headphones connected to HEADPHONE; At best I get a little crackle (which may be from amplifier) when I turn the amp up fairly high.


If I set CHIP_ANA_CTRL to 0x44 instead of 0x4 the headphones start playing the 'source' back, albeit with artefacts it seems, but nothing I have tried seems to enable either LINEIN->DAP(MAIN)->DAC->LINEOUT nor LINEIN->DAP(MAIN)->DAC->HEADPHONE and I am starting to think that I have missed something that I will not 'unmiss' without help...


I can 'flesh out' why I chose those values for the registers above, that will make a fairly large post (which this is already approaching even without), but I figure it likely that whoever really can help me does not need it fleshed out.


Please help if you can, don't hesitate to comment if you want to (even if positive your comment won't really help me!)