I try to DMA both RDR data ports of a MK20DX256. I seems that RDR1 does not deliver data and remains always zero.
In fact DMA only from I2S0_RDR0 works, but simply replacing the source with I2S_RDR1 does not work, the DMA seem to run freely (i.e. MUCH more isr calls than with RDR0).
DMA from both data ports, gives the first good data on first data port and zero on second data port.
This was observed on a Teensy3.1 by PJRC
All register settings were double checked and should also be no issue, as DMA from RDR0 works, and RDR1 is located only 4 bytes higher.
Question: Is there a known issue with I2S0_RDR1, or using this port as source for DMA?