目前硬件上i2s各个引脚一直为0V 没有信号，供电是正常的。这是什么原因呢
原理图是如上连接：
mcasp0_pins: mcasp0_pins {
pinctrl-single,pins = <
0x1ac (PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* rmii1_ref_clk.mcasp0_ahclkx */
0x190 (PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* mii1_crs.mcasp0_aclkx */
0x194 (PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* mii1_rxerr.mcasp0_fsx */
0x198 (PIN_OUTPUT_PULLDOWN | MUX_MODE0) /* mii1_col.mcasp0_axr0 */
0x1a8 (PIN_INPUT_PULLDOWN | MUX_MODE0) /* rmii1_ref_clk.mcasp0_axr1 */
>;
};
mcasp0_pins_sleep: mcasp0_pins_sleep {
pinctrl-single,pins = <
0x1ac (PIN_OUTPUT_PULLDOWN | MUX_MODE0)
0x190 (PIN_OUTPUT_PULLDOWN | MUX_MODE0)
0x194 (PIN_OUTPUT_PULLDOWN | MUX_MODE0)
0x198 (PIN_OUTPUT_PULLDOWN | MUX_MODE0)
0x1a8 (PIN_OUTPUT_PULLDOWN | MUX_MODE0)
>;
};
&mcasp0 {
pinctrl-names = "default", "sleep";
pinctrl-0 = <&mcasp0_pins>;
pinctrl-1 = <&mcasp0_pins_sleep>;
fsl,mode = "i2s-slave";
status = "okay";
op-mode = <0>; /* MCASP_IIS_MODE */
tdm-slots = <2>;
/* 4 serializers */
serial-dir = < /* 0: INACTIVE, 1: TX, 2: RX */
1 2 0 0
>;
tx-num-evt = <32>;
rx-num-evt = <32>;
};
sound {
compatible = "fsl,imx-audio-sgtl5000";
ti,model = "AM335x-EVMSK";
ti,audio-codec = <&sgtl5000>;
ti,mcasp-controller = <&mcasp0>;
ti,codec-clock-rate = <24000000>;
ti,audio-routing =
"Mic Jack", "MIC3L";
};
clocks{
clk_24M: codec_clock {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <24000000>;
};
sgtl5000: sgtl5000@12{
compatible = "fsl,sgtl5000";
reg = <0x12>;
clocks = <&clk_24M>;
VDDA-supply = <&vaux2_reg>;
VDDIO-supply = <&vaux2_reg>;
VDDD-supply = <&vbat>;
};
设备树如上：
