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CCS/TDA3LA: How to switch SD Host to UHS Mode

Part Number: TDA3LA

Tool/software: Code Composer Studio


I connected TDA3 to SD card and configured it as SD Host.
Then I need to switch both the Host and the Card to UHS mode. There is enough information in SD Physical Layer Specification how to switch the card to UHS mode. But this is not so with the Host.
I've found needed bit fields in MMCHS_AC12 register, such as UHSMS, V1V8_SIGEN etc. in TDA3 Reference Manual. But there is no any UHS Mode Switch flow in the document. I haven't also found it in examples.

So, where can I find this information?

Thank you!

  • Oh, I took wrong question.

    The right question is: Can I make an output signal voltage of 1,8V at an interface voltage of 3.3 V?

  • Hi,

    I am assuming you are using Linux Kernel for MMC.

    There are two configurations in dts for MMC power supply

    1) vmmc-supply : The Vdd voltage supply for the card.
    2) vmmc_aux-supply : The Vio voltage supply for IO lines.

    Example from TI EVM Linux kernel dts below

    &mmc1 {
            status = "okay";
            vmmc-supply = <&evm_3v3_sd>;
            vmmc_aux-supply = <&ldo1_reg>;
            bus-width = <4>;
    evm_3v3_sd: fixedregulator-sd {
            compatible = "regulator-fixed";
            regulator-name = "evm_3v3_sd";
            regulator-min-microvolt = <3300000>;
            regulator-max-microvolt = <3300000>;
            gpio = <&pcf_gpio_21 5 GPIO_ACTIVE_HIGH>;
    ldo1_reg: ldo1 {
            /* LDO1_OUT --> SDIO  */
            regulator-name = "ldo1";
            regulator-min-microvolt = <1800000>;
            regulator-max-microvolt = <3300000>;