Turn on I2S clocks before sending data

[juliantbrown]

I'm working with TI's TAS2555 DAC as an audio output driven by the NRF52 via I2S. This DAC requires that the I2S clocks (MCK, SCK, and LRCK) are enabled prior to any data transmission, at a specific point in the middle of the I2C initialization sequence. I'm currently handling this by calling the nrfx_i2s_start and passing in 0s in the buffers for audio output data until init is completed and I'm ready to play audio. This works fine, but I wanted to ask if anyone knew of a cleaner way to enable clocks without having to pass in data. From what I can tell, the clock generation is kicked off by the NRF_I2S_TASK_START task and I don't see any obvious alternative, but I'm curious if there's something I might be missing.

Any advice would be appreciated! Thanks!

[haakonsh]

Hey Julian,

Usually these kinds of devices needs to receive a certain amount of clock pulses before they can accept any data input. The usual way is to write that 'certain amount' of 0s to the output buffers. We do not have any special feature that does this for you in HW or SW. 

Cheers,

Håkon.