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Summary

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The serial console is essential for communication with and development of your design. This how-to guide will demonstrate the steps required to change the default serial debug console configuration.

Specifically, the phyBOARD-Zeta uses UART5 as the default serial console. This requires a breakout cable assembly to expose the RS-232 pins that are available on a pin header on the Zeta board, a null modem cable, and finally an RS-232 cable to the host. The PEB-EVAL-02 board exposes UART1 via the RS-232 protocol on a DB9 connector. This will be the target configuration that the how-to guide will demonstrate.

<Picture of phyBOARD-Zeta with UART5 and UART1 marked>This is a summary of the how to.

Step-by-step guide

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u-boot

To change the serial console for u-boot, you'll need to modify the CONFIG_CONS_INDEX and CONFIG_MXC_UART_BASE definitions in the u-boot source.

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&uart1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart1>;
	assigned-clocks = <&clks IMX7D_UART1_ROOT_SRC>;
	assigned-clock-parents = <&clks IMX7D_PLL_SYS_MAIN_240M_CLK>;
	status = "okay";
};

Linux

Change the SERIAL_CONSOLE to indicate the desired 'ttymxc' device in the imx7d_phyboard_zeta_001 machine configuraiton. In this case, we will change it from a 4 to a 0:

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&uart1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart1>;
	assigned-clocks = <&clks IMX7D_UART1_ROOT_SRC>;
	assigned-clock-parents = <&clks IMX7D_PLL_SYS_MAIN_240M_CLK>;
	status = "okay";
};

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