Need support for SAI_RX2 issue

[LydieCDO]

Hi NXP support,

We are working with IMXRT1176 and we are facing some issues.

Here is the context:

Using SAI1 on IMX1176, we are currently trying to use SAI1_RX2 to receive data from a tuner (SI47952) but we only get 0.
IMX is the master, and the tuner is slave.

GPIO DISP_B2_01 is configured as SAI1_RX2
If we monitor the connection, we can see that the signal is squeeze to 0 and almost 0V (see attached picture)

We have done the test of connecting the tuner to SAI1_RX0 (instead of SAI1_RX2) and it we did get the correct signal/data.
That means the issue is on the IMX side, we think this can be a pin config issue as the DISP_B2_01 is SAI1_RX2 and SAI1_TX2 but we don't know how to force RX mode.

Here some SAI1 registry dump during transfers
tcr1: 0x10 tcr2: 0x7000007 tcr3: 0x10000 tcr4: 0x10010f3b tcr5: 0xf0f0f00
rcr1: 0x10 rcr2: 0x47000007 rcr3: 0x40000 rcr4: 0x10010f1b rcr5: 0xf0f0f00

Do you have any idea to unlock this situation ?

Many thanks for your support.

[Aubineau_FAE]

Hi,

But what is the value of R4261? it is O or another value, it is to ensure the i.MX force the pin to 0V.

Vincent

[eric_delanghe]

Hi again,

R4261 is a 0ohm, it's here to cut the lane and re-route if something goes wrong in the design.

Best regards,
Eric

[Aubineau_FAE]

Hi,

OK, so if an th RT is driving its pin low it cannot really be detected as it is a direct short circuit.

If you configure this pin as a GPIO, in input mode, do you still have the issue?:

vincent_aubinea_0-1646752468615.png

vincent_aubinea_1-1646754346122.png

Vincent

[eric_delanghe]

Hello,

If I configure DISP_B2_01 as GPIO5_02 the level is correct on the lane !
That means the issue come from the SAI configuration.

There is this diagram in the SAI documentation.

Screenshot from 2022-03-10 17-31-40.png

TX_DATA2 is used for sai_rxdata2 if "obe" is 0 but there is no information about this "obe". My thought was that it is configured by register TCR4 on bits TCE "Transmit Channel Enable"
And as I posted TCR4 is 0x10010f3b so TCE is 0x1 (TX0 enable, other are disabled)

Any information about that ?

[eric_delanghe]

Also you said that " It is not possible to have hard pull-down in this case."

We already tried to remove it and it does not help

[mike_susen]

Hi @eric_delanghe 

what about GPIO_DISP_B2_00? do you see same behavior also on tis pin? 

Mike

[eric_delanghe]

Hello @mike_susen ,

We don't actually have DAB feature implemented.

But I'll ask hardware guys to patch my board to get FM data on GPIO_DISP_B2_00.

I will also ask hardware guys to connect the microphone (currently GPIO_DISP_B2_06) on GPIO_DISP_B2_01.

Best regards,

Eric

[rastislav_pavlanin]

Hi @mike_susen ,

could you please take this request?

thanks. 

regards

R.