IMX8mp MCU uart

[XuYazhuo]

Hi,

    I use imx8mp board. Now, I want to use uart3 as a uart of M7,  not as a 485 serial port for A53 core. I have deleted uart3 in dts of A53，and config pin-mux in M7, but uart3 haven't worked.

I config pin blow in file rtos_examples/freertos_uart/pin_mux.c

void BOARD_InitPins(void) { /*!< Function assigned for the core: Cortex-M7F[m7] */
IOMUXC_SetPinMux(IOMUXC_UART4_RXD_UART4_RX, 0U);
IOMUXC_SetPinConfig(IOMUXC_UART4_RXD_UART4_RX,
IOMUXC_SW_PAD_CTL_PAD_PUE_MASK |
IOMUXC_SW_PAD_CTL_PAD_PE_MASK);
IOMUXC_SetPinMux(IOMUXC_UART4_TXD_UART4_TX, 0U);
IOMUXC_SetPinConfig(IOMUXC_UART4_TXD_UART4_TX,
IOMUXC_SW_PAD_CTL_PAD_PUE_MASK |
IOMUXC_SW_PAD_CTL_PAD_PE_MASK);

IOMUXC_SetPinMux(IOMUXC_UART3_RXD_UART3_RX, 0U);
IOMUXC_SetPinConfig(IOMUXC_UART3_RXD_UART3_RX,
IOMUXC_SW_PAD_CTL_PAD_PUE_MASK |
IOMUXC_SW_PAD_CTL_PAD_PE_MASK);
IOMUXC_SetPinMux(IOMUXC_UART3_TXD_UART3_TX, 0U);
IOMUXC_SetPinConfig(IOMUXC_UART3_TXD_UART3_TX,
IOMUXC_SW_PAD_CTL_PAD_PUE_MASK |
IOMUXC_SW_PAD_CTL_PAD_PE_MASK);
}

[joanxie]

refer to the dts file, imx8mp-evk.dts enable uart3

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mp-evk.d...

[XuYazhuo]

hi, I refered this dts to enable uart3, but I can't send or receive data then I use freertos_uart  example。

Anywhere else I need to config?

[joanxie]

try to disable in the dts file firstly if you want to M core to use this uart

[XuYazhuo]

yes,I have disabled uart3 in dts。Then,I  config pins of uart3 in pin-mux.c like above 。Any else do I need to do ?

[joanxie]

I checked ATF, only UART2 is assigned to domain, so you don't need to change this

https://source.codeaurora.org/external/imx/imx-atf/tree/plat/imx/imx8m/imx8mp/imx8mp_bl31_setup.c?h=...

you also can refer to the imx8mp-evk-rpmsg.dts if you use this to the linux boot, current bsp disable uart4

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mp-evk-r...

[XuYazhuo]

so it is. But now I want more uart for mcu,  use uar3 as a uart of M7。The data enter via uart3 to M7，like this.