AM5728: Enabling McASP2 Without Codec

David Tan1

Part Number: AM5728

Hello,

I'm using the TI SDK 6.02.00.81 with an evaluation board trying to get mcasp2 up and running without using a codec. Basically, I'm just interested in sending i2s data across the mcasp2 lines.

I've made the following changes:

U-boot snippet changes:

{MCASP2_ACLKX, (M0 | PIN_INPUT_PULLDOWN)},
{MCASP2_FSX, (M0 | PIN_INPUT_SLEW)},
{MCASP2_FSR, (M0 | PIN_INPUT_SLEW)},	
{MCASP2_AXR0, (M0 | PIN_INPUT_SLEW)},	
{MCASP2_AXR1, (M0 | PIN_INPUT_SLEW)},	
{MCASP2_ACLKR, (M0 | PIN_INPUT_PULLUP)},

I edited my u-boot uEnv.txt to select the am57xx-beagle-x15-common.dtb device tree to use.

Device Tree Modifications to am57xx-beagle-x15-common.dtsi:

&mcasp2 {
	#sound-dai-cells = <0>;
	assigned-clocks = <&l4per_clkctrl DRA7_MCASP2_CLKCTRL 24>;
	assigned-clock-parents = <&sys_clkin2>;
	status = "okay";

	op-mode = <0>;	/* MCASP_IIS_MODE */
	tdm-slots = <2>;
	/* 16 serializers */
	serial-dir = <	/* 0: INACTIVE, 1: TX, 2: RX */
		1 2 0 0 
		0 0 0 0 
		0 0 0 0 
		0 0 0 0
	>;
	tx-num-evt = <32>;
	rx-num-evt = <32>;
};

And for a basic test, I've changed the original sound0 node to use mcasp2 instead of mcasp3:

sound0: sound0 {
		compatible = "simple-audio-card";
		simple-audio-card,name = "TW";
		simple-audio-card,widgets =
			"Line", "Line Out",
			"Line", "Line In";
		simple-audio-card,routing =
			"Line Out",	"LLOUT",
			"Line Out",	"RLOUT",
			"MIC2L",	"Line In",
			"MIC2R",	"Line In";
		simple-audio-card,format = "dsp_b";
		simple-audio-card,bitclock-master = <&sound0_master>;
		simple-audio-card,frame-master = <&sound0_master>;
		simple-audio-card,bitclock-inversion;

		simple-audio-card,cpu {
			sound-dai = <&mcasp2>;
		};

		sound0_master: simple-audio-card,codec {
			sound-dai = <&tlv320aic3104>;
			clocks = <&clkout2_clk>;
		};
	};

The board boots up fine, and I've loaded a basic .wav file to playback. However, I don't see any activity coming out of mcasp2. As a sanity check, if I change back to mcasp3 for the sound0 node, I do hear sound coming out from the audio jack. What could be the reason I don't see any activity happening on the mcasp2 after making my changes?

over 5 years ago

0 jian35385 over 5 years ago

TI__Mastermind 23125 points

David,

could you confirm how do you verify McASP2 activity when you mentioned:

"I don't see any activity coming out of mcasp2"

I have not checked the EVM schematics, but I assume you will need to scope to see the data on the lines?

regards

jian

0 David Tan1 over 5 years ago in reply to jian35385

Intellectual 280 points

Hello Jian,

I've brought out the McASP2 lines from the AM5728 dev board by soldering some wires to P17 connector.

Since then, I have been successfully able to record and play audio stream to the following two breakout boards bought from adafruit:

Adafruit I2S MEMS Microphone Breakout - SPH0645LM4H
Adafruit I2S Stereo Decoder - UDA1334A Breakout

The device tree modifications I've made to am57xx-beagle-x15-common.dtsi

sound0: sound0 {
		compatible = "simple-audio-card";
		simple-audio-card,name = "Trellisware";
		simple-audio-card,format = "i2s";
		simple-audio-card,bitclock-master = <&sound0_master>;
		simple-audio-card,frame-master = <&sound0_master>;

		sound0_master: simple-audio-card,cpu {
			sound-dai = <&mcasp2>;
			clocks = <&clkout2_clk>;
		};

		simple-audio-card,codec {
			clocks = <&clkout2_clk>;
			sound-dai = <&tlv320aic3104>;
		};
	};

&mcasp2 {
	#sound-dai-cells = <0>;
	assigned-clocks = <&l4per_clkctrl DRA7_MCASP2_CLKCTRL 24>;
	assigned-clock-parents = <&sys_clkin2>;
	status = "okay";

	op-mode = <0>;	/* MCASP_IIS_MODE */
	tdm-slots = <2>;
	/* 16 serializers */
	serial-dir = <	/* 0: INACTIVE, 1: TX, 2: RX */
		1 2 0 0 
		0 0 0 0 
		0 0 0 0 
		0 0 0 0
	>;
	tx-num-evt = <32>;
	rx-num-evt = <32>;
};

From experimentation, it seems McASP2 is operating in sync mode where the TX ACLKX and AFSX signal lines also act as the RX clk and frame sync.

Is there a way to separate them out so that the RX CLK and frame sync are independent of TX?

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AM5728: Enabling McASP2 Without Codec