AN00247_xua_example_spdif_tx and AN00248_xua_example_pdm_mics untested

[ed-xmos]

AN00248_xua_example_pdm_mics and AN00248_xua_example_pdm_mics both use custom mains where null is passed in for I2S resources.
The XUA_AudioHub() supports null resources but ConfigAudioPortsWrapper() does not which causes a runtime exception where a null is passed to a non-nullable param.

I note that in both cases:

#define I2S_CHANS_DAC (0)
#define I2S_CHANS_ADC (0)

is set. This seems to be overlapping with setting resources to null in XUA_AudioHub so the design idiom for no I2S should be tidied.

Both of these examples need to be hardware tested too since this issue may have existed for a while.

[nhmasterolt]

In my case, building the annotation note indeed completes successfully, but simulation using xsim yields the error
Unhandled exception: lib_xua/src/core/audiohub/xua_audiohub.xc:789:24: error: passing null argument to a non-null parameter
p_mclk_in, clk_audio_bclk, divide, curSamFreq);

Might be related to the issue above?