RMII interface missing TX_CLK on i.MX1062 [Solved]

[robert-hh]

Hello all,

I fail to get the 50MHz TX_CLK signal of the MCU. The interface are set according to the examples. Communication on the MII interface works. I can get up the LAN interface and see short indication of traffic on at the traffic LED.

But there is no 50MHz clock at the TX_CLK output and the respecive transceiver input. The Pin is GPIO_B1_10, which is properly routed. From what I can tell in the oscilloscope, the TX_CLK pin seems to be floating. The Pin is set up as:

IOMUXC_SetPinMux(IOMUXC_GPIO_B1_10_ENET_REF_CLK, 1U);
IOMUXC_SetPinConfig(IOMUXC_GPIO_B1_10_ENET_REF_CLK, 0x31u);

The clock is configured with:

const clock_enet_pll_config_t config = {
.enableClkOutput = true, .enableClkOutput25M = false, .loopDivider = 1};
CLOCK_InitEnetPll(&config);

IOMUXC_EnableMode(IOMUXC_GPR, kIOMUXC_GPR_ENET1TxClkOutputDir, true);

That works with different Pin settings for   i.XRT1021, but not for this model.

Best Regards, Robert

[robert-hh · Accepted solution]

Solved by careful reading the examples and the related messages in the forum. The clock signal settings in the CCM ANALOG section had to made properly. At least it was not just a single item missing.

Interesting that on the .iMXRT 1021 that part worked 'out of the box'.

Best Regards, Robert