i.MX8MM. CCM OUTPUT

EErdem — Sun, 08 Nov 2020 11:49:59 GMT

Hello, I am designing a custom board using i.MX8MM.

There are four different ICs that need External Xtal for proper operations.

KSZ9131RNXC Ethernet PHY needs 25 MHz Clock Input.

DSI to HDMI converter needs 25MHz clock Input.

USB HUB needs 12 MHz clock input.

Do I have to use external XTAL for all ICs or can I provide the necessary clock input from i.MX8MM CCM outputs.

From the application note what I understood The SoC can provide external clock output using

CCM pins. Is that possible to provide all these clock inputs from these pins and how can I set them

And Do you have any idea about clock integrity as a PPM

Re: i.MX8MM. CCM OUTPUT

igorpadykov — Mon, 09 Nov 2020 01:11:47 GMT

Hi EErdem

for external clock output using CCM one can look at imx8mm-evk.dts :

pinctrl_csi_rst: csi_rst_grp {

fsl,pins = <
MX8MM_IOMUXC_GPIO1_IO14_CCMSRCGPCMIX_CLKO1 0x59
ov5640_mipi: ov5640_mipi@3c {
..<&pinctrl_csi_rst>;

clocks = <&clk IMX8MM_CLK_CLKO1>;

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mm-evk.dts?h=imx_5.4.47_2.2.0

Output clock stability (ppm) is defined by used crystal.

Best regards
igor

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i.MX8MM. CCM OUTPUT

Re: i.MX8MM. CCM OUTPUT