DAC+ Pro: connect external I2S DACs
Connecting external DACs via I2S is not an easy process. Unlike SPDIF, I2S is not designed as an interface between devices, but an interconnect between digital audio chips. Both sides have to be configured exactly the same way. You should know all the details about I2S (clocks, master/slave, bits per sample) before even thinking about connecting an additional DAC. We won’t give any support for this feature and we can’t guarantee that the output will be compatible to a specific DAC chip. Don’t even think about using this if you are not used to debug digital circuits with an oscilloscope or a logic analyzer. This is only for experienced electronics designers! Also note that soldering on the board voids the warranty.
There is no support for this feature! This document is the only documentation that it available. We won’t offer additional documents or support.
The I2S header is located on the edge of the board and it is named P4
There are 5 pins carrying the following signals:
|2||Master clock (22.5792MHz for 44.1, 88.2, 176.4 kHz sample rates, 24.576MHz for 48,96,192kHz sample rates)|
|3||Bit clock (frequency = 32/64* sample rate)|
|4||Frame clock (frequency = sample rate)|
Signal voltage is 3.3V.