AM62A7-Q1: The SPI wave is not good work as SPI master

Guobing Miao

Prodigy 20 points

Part Number: AM62A7-Q1
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi,

We get a problem that SPI signal not looks good, as show in the picture, it have a long tail on every frame data.

Am62A work as master with PIO mode,

Here is our config:

spi0_pins_default: spi0-default-pins {
		pinctrl-single,pins = <
			AM62AX_IOPAD(0x1b4, PIN_OUTPUT, 0) /* (D16) SPI0_CS0 - SOC_SPI0_nCS0  */
			AM62AX_IOPAD(0x1bc, PIN_INPUT, 0) /* (A17) SPI0_CLK - SOC_SPI0_CLK */
			AM62AX_IOPAD(0x1c0, PIN_OUTPUT, 0) /* (B15) SPI0_D0 - SOC_SPI0_MOSI */
			AM62AX_IOPAD(0x1c4, PIN_INPUT, 0) /* (E15) SPI0_D1 - SOC_SPI0_MISO */
		>;
};


&main_spi0 { status = "okay"; pinctrl-names = "default"; pinctrl-0 = <&spi0_pins_default>; ti,pindir-d0-out-d1-in; // set SPI0_D0: MOSI, SPI0_D1: MISO, default: d0-in-d1-out(SPI0_D0: MISO, SPI0_D1: MOSI) mcu-connector@0 { compatible = "ti,spi-mcu"; reg = <0>; spi-max-frequency = <5000000>; }; };

17 days ago

0 Andreas Dannenberg 16 days ago

TI__Guru 66842 points

All I/O pads should be configured as PIN_INPUT when used with the SPI peripheral module, see this example here from the Kernel tree: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-am625-sk-mcspi-loopback.dtso?h=ti-linux-6.12.y (note the actual I/O direction is controlled by the SPI peripheral, the padconfig merely describes which pad features are enabled and disabled like input buffers etc.). Can you please give this a try.

This is also how the pinconfig is generated by our SysConfig pinmux tool at https://www.ti.com/tool/SYSCONFIG .

Regards,
Andreas

0 Guobing Miao 16 days ago in reply to Andreas Dannenberg

Prodigy 20 points

I try change I/O PIN_INPUT in device tree, but still have this problem.

And our signal CS pin always will enabled before the CLK and MOSI have 500mv,

0 Guobing Miao 16 days ago in reply to Andreas Dannenberg

Prodigy 20 points

what mean sysconfig pinmux, I not use sysconfig to config before in am62a platform,

Do I need to change something with SYSCONFIG for SPI usage in Linux?

0 Andreas Dannenberg 15 days ago in reply to Guobing Miao

TI__Guru 66842 points

SysConfig is a tool that allows you to create pinmux (pad config) definitions in device tree syntax using a graphical user interface. This works on a per-peripheral basis and helps to ensure the correct pinmux definitions are used.

So which signal is it that looks floating? The MOSI signal? Try enabling a pull-up or pull-down for that signal. It is probably not driven when the master is not active (to allow other masters to control the signal).

Regards, Andreas

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AM62A7-Q1: The SPI wave is not good work as SPI master