Hi, Since M1R4 will try to let user have an expansion daughter board built on the top of around current audio codec area. So reduced J3 and branched into two few pins header instead of existing J3 to reserve space layout route, but they are being unpopulated footprints for 100 mil (2.54 mm) headers as: J23:1 AUDIO_AGND J23:2 CD_L J23:3 CD_R J23:4 CD_GND
J3:1 LNLVLOUT_L J3:2 AUDIO_AGND J3:3 LNLVLOUT_R Although there's no much discussions about this feature on SPDIF extension header, Roh asked in #milkymist once, http://en.qi-hardware.com/mmlogs/milkymist_2012-02-15.log.html#t01:46 here's we can also add an 2.54mm extension header with unpopulated footprint as: Js:1 GND Js:2 SPDIF_ENABLE Js:3 SPDIF_OUT Js:4 3V3 To use SPDIF feature, you can build your own SPDIF-related circuit in expansion board like figure 19 on page 33 of http://www.wolfsonmicro.com/documents/uploads/data_sheets/en/WM9707.pdf Do you like? and how do you think of this? Comments are welcome. ref. : 1. http://en.wikipedia.org/wiki/S/PDIF 2. latest M1R4 draft schematic: http://downloads.qi-hardware.com/hardware/milkymist_one/sch/tmp/MILKYMISTONE.pdf Thanks, - adam
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