Kinetis MicrocontrollersのトピックRe: Kinetis SAI Support for TDM?

Kinetis SAI Support for TDM?

eli_hughes — Tue, 11 Nov 2014 16:12:40 GMT

I think the SAI section for the K64F (and variants) needs some clarification with regards to the Frame Sync With. The prose in the manual claims TDM support, but I cannot see from the manual how you can get a proper frame sync as you cannot set the width to a large enough value.

I don't think the TDM capability based upon what is in the register description. For example, let’s say I am trying to configure for an 8-channel TDM (for example a cirrus logic CS5368). This requires a word length of 32-bits and 8 words per frame. This means that the frame sync should be active for 4 words (128 bits).

Let’s consider the setup for a receiver. I am assume, BCLK MCLK and FRAME SYNC are generated *externally* by an ADC.

RCR4 setups up the frame sync. I can set FRSZ (bits 20-16) as 7 (gives me 8 words per frame).

The problem is in SYWD. (Bits 12-8). It claims that I can on set the value in bits and the width cannot be longer than the 1^st word of the frame. This is not an issue for I2S or PCM. It appears that you cannot support TDM with the SAI. The frame sync must be able to a width of ½ of the total number of words. 4 words (128 bits).

Can someone confirm this?

Re: Kinetis SAI Support for TDM?

Kan_Li — Thu, 13 Nov 2014 06:46:38 GMT

I am sorry , but referring to the data sheet of CS5368, TDM format just needs a FS of word wide at max, it is not what you mentioned "a width of ½ of the total number of words. 4 words (128 bits)." is there any misunderstanding?

Please kindly refer to page 26 of http://www.go-gddq.com/downlocal/cs/CS5368.pdf for details.

Have a great day,
Kan

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Re: Kinetis SAI Support for TDM?

eli_hughes — Thu, 13 Nov 2014 15:59:29 GMT

Kan:

Here is the diagram I was was refering to:

(Page 23 of the datasheet http://www.cirrus.com/en/pubs/proDatasheet/CS5368_F5.pdf)

It looks like your picture is from a different version. In the picture I have attached, it shows the frame sync 4 words wide.

I am getting a PCB in a couple weeks to actually probe to verify the timing..... Hopefully I can make it work@

A quick question though.... If the SAI is operating in TDM Slave, does it actually care about the width of the FS pulse? I.E. Would it only look for a rising edge to start a new frame?

Re: Kinetis SAI Support for TDM?

Kan_Li — Fri, 14 Nov 2014 02:14:23 GMT

RM says"

The frame sync signal is used to indicate the start of each frame. A valid frame sync

requires a rising edge (if active high) or falling edge (if active low) to be detected and the

transmitter or receiver cannot be busy with a previous frame. A valid frame sync is also

ignored (slave mode) or not generated (master mode) for the first four bit clock cycles

after enabling the transmitter or receiver."

so in my understanding, I think this signal should be a edge signal to SAI module.

Have a great day,
Kan