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SK-AM62P-LP: How to Set SD Card to 3.3v only (low speed)

YuYuan Wang
Prodigy 140 points
Part Number: SK-AM62P-LP
Other Parts Discussed in Thread: AM62P

Tool/software:

Since my future board’s SD card doesn't support switching between 1.8V and 3.3V (we only provide 3.3V), I want to verify if this is feasible on the EVM.

I checked the schematic and the control pin is Y25 (GPIO0_31)

The related DTS in u-boot as below

&main_pmx0 {
	vddshv_sdio_pins_default: vddshvr-sdio-default-pins {
		pinctrl-single,pins = <
			AM62PX_IOPAD(0x007c, PIN_INPUT, 7) /* (Y25) GPMC0_CLK.GPIO0_31 */
		>;
		bootph-all;
	};
};

/{
	vddshv_sdio: regulator-3 {
		compatible = "regulator-gpio";
		regulator-name = "vddshv_sdio";
		pinctrl-names = "default";
		pinctrl-0 = <&vddshv_sdio_pins_default>;
		regulator-min-microvolt = <1800000>;
		regulator-max-microvolt = <3300000>;
		regulator-boot-on;
		gpios = <&main_gpio0 31 GPIO_ACTIVE_HIGH>;
		states = <1800000 0x0>,
			 <3300000 0x1>;
		bootph-all;
	};
};

&sdhci1 {
	/* SD/MMC */
	status = "okay";
	vmmc-supply = <&vdd_mmc1>;
	vqmmc-supply = <&vddshv_sdio>;
	pinctrl-names = "default";
	pinctrl-0 = <&main_mmc1_pins_default>;
	disable-wp;
	bootph-all;
};

But I checked the TP33 (VDDSHV_SDIO), and it is still in 1.8v even I add the line "no-1-8-v;"

If I directly mask the "vqmmc-supply", it can't even boot into U-Boot.

console output

Does anyone know how to make the SD card use only 3.3V?

Thanks!

  • +1
    TI__Mastermind 49506 points

    Hi, can you please try the following diff to disable all the UHS modes & then check the voltage

    diff --git a/arch/arm/dts/k3-am62p-main.dtsi b/arch/arm/dts/k3-am62p-main.dtsi
index 652908cf0d0..018c36be970 100644
--- a/arch/arm/dts/k3-am62p-main.dtsi
+++ b/arch/arm/dts/k3-am62p-main.dtsi
@@ -605,11 +605,11 @@
 		ti,clkbuf-sel = <0x7>;
 		ti,otap-del-sel-legacy = <0x0>;
 		ti,otap-del-sel-sd-hs = <0x0>;
-		ti,otap-del-sel-sdr12 = <0xf>;
-		ti,otap-del-sel-sdr25 = <0xf>;
-		ti,otap-del-sel-sdr50 = <0xc>;
-		ti,otap-del-sel-ddr50 = <0x9>;
-		ti,otap-del-sel-sdr104 = <0x6>;
+		// ti,otap-del-sel-sdr12 = <0xf>;
+		// ti,otap-del-sel-sdr25 = <0xf>;
+		// ti,otap-del-sel-sdr50 = <0xc>;
+		// ti,otap-del-sel-ddr50 = <0x9>;
+		// ti,otap-del-sel-sdr104 = <0x6>;
 		ti,itap-del-sel-legacy = <0x0>;
 		ti,itap-del-sel-sd-hs = <0x0>;
 		ti,itap-del-sel-sdr12 = <0x0>;

    Regards,

    Prashant

  • 0 in reply to Prashant Shivhare
    Prodigy 140 points

    Hi, ,

    Thanks! I measured 3.3V on TP33

    This modification needs to be made on both sides (Kernel & u-boot), right?

    I've updated my dts 

    &sdhci1 {
	/* SD/MMC */
	status = "okay";
	vmmc-supply = <&vdd_mmc1>;
//	vqmmc-supply = <&vddshv_sdio>;
    /delete-property/ ti,otap-del-sel-sdr12;
	/delete-property/ ti,otap-del-sel-sdr25;
	/delete-property/ ti,otap-del-sel-sdr50;
	/delete-property/ ti,otap-del-sel-ddr50;
	/delete-property/ ti,otap-del-sel-sdr104;
	no-1-8-v;
	pinctrl-names = "default";
	pinctrl-0 = <&main_mmc1_pins_default>;
	disable-wp;
	bootph-all;
};

  • 0 in reply to YuYuan Wang
    TI__Mastermind 49506 points

    Hi YuYan,

    YuYuan Wang said:
    This modification needs to be made on both sides (Kernel & u-boot), right?

    That is correct. The AM62P DTS (arch/arm64/boot/dts/ti/k3-am62p5-sk.dts) in the Linux Kernel should also have the same changes.

    Regards,

    Prashant