SAI1 mclk output waveform IMX6G2 microchip

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SAI1 mclk output waveform IMX6G2 microchip

295件の閲覧回数
59174711
Contributor I

Hi all,

I'm developing beep audio feature with imx6g2 micro and used the SAI1 MCLK interface to output a reference clock for an audio converter (that is TI tlv320dac3100). My SAI1 mclk output is a waveform similar to a sine wave. Is it correct?

Here's my code to configure sai1 clock root.

const clock_audio_pll_config_t g_ccmConfigAudioPll =
{
.loopDivider = 30,
.postDivider = 2,
.numerator = 72,
.denominator = 100
};

/* Set SAI1 MCLK pin mux */
IOMUXC_SetPinMux(IOMUXC_CSI_DATA01_SAI1_MCLK, 6U);
IOMUXC_SetPinConfig(IOMUXC_CSI_DATA01_SAI1_MCLK,
IOMUXC_SW_PAD_CTL_PAD_DSE(7U) |
IOMUXC_SW_PAD_CTL_PAD_SPEED(2U));

/* Enable SAI1 MCLK output */
IOMUXC_GPR_GPR1 |= IOMUXC_GPR_GPR1_SAI1_MCLK_DIR_MASK;
/* Enable PLL4 608.64M */
CLOCK_InitAudioPll(&g_ccmConfigAudioPll);
/* Set SAI source to PLL4*/
CLOCK_SetMux(kCLOCK_Sai1Mux, 2);
/* Set SAI pre-divider to 6 */
CLOCK_SetDiv(kCLOCK_Sai1PreDiv, 5U);
/* Set SAI divider to 10 */
CLOCK_SetDiv(kCLOCK_Sai1Div, 9U);

And the following pic is my sai1.mclk waveform captured from the scope. Output frequency is 6.16MHz.MCLK.jpg

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228件の閲覧回数
igorpadykov
NXP TechSupport
NXP TechSupport

Hi Damon

sine waveform may be caused by weak drive strength and capacitive load,

one can try to increase drive strength using DSE field in

SW_PAD_CTL_PAD_x_y SW PAD Control Register described in IOMUX Chapter

of Reference Manual

Best regards
igor
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228件の閲覧回数
59174711
Contributor I

I tried your suggestion, but it didn't work. Before I set the DSE value to 7, I tried value 2 as you told me. The result is no change.

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228件の閲覧回数
igorpadykov
NXP TechSupport
NXP TechSupport

one can also try to decrease mclk frequency.

Best regards
igor

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