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IOMUX Configuration for SAI

Question asked by Paul Katarzis on Feb 6, 2020
Latest reply on Feb 6, 2020 by Paul Katarzis

I am working on a custom board equipped with an i.MX8 QXP. The lines SAI1_TXFS, SAI1_TXC, SAI1_RXD, and SAI1_TXD are connected to an audio codec. The only thing between the i.MX8 and the audio codec on each line are series resistors with values of 22 ohm or 0 ohms. In particular, on the SAI1_TXFS line, there is a 22 ohm resistor near the i.MX8 and a 0 ohm resistor near the audio codec. When I use a scope to measure the frame sync signal on the side of the 22 ohm resistor connected directly to the i.MX8 I see a maximum voltage of about 3.3 V as expected. However, on the other side of the 22 ohm resistor the maximum voltage is about 0.8 V. This seems to indicate that there is a large amount of current on this line. I actually see something similar on all SAI1 lines.

 

My device tree includes fsl-imx8qxp.dtsi and adds the following:

 

pinctrl_sai1: sai1grp {
fsl,pins = <
SC_P_FLEXCAN0_TX_ADMA_SAI1_TXFS 0x06000060
SC_P_FLEXCAN0_RX_ADMA_SAI1_TXC 0x06000060
SC_P_FLEXCAN1_TX_ADMA_SAI1_RXD 0x06000060
SC_P_FLEXCAN1_RX_ADMA_SAI1_TXD 0x06000060
>;
};

 

&sai1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sai1>;

status = "okay";
};

 

The sai1grp node is defined within the iomuxc node. Could my pinctrl configuration be causing this issue?

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