i.MX8QXP set Dual Voltage Pad Level

nolan_zinn — Thu, 26 Mar 2020 23:57:39 GMT

I've been working with GPIOs on an i.MX8QXP MEK with Baseboard. The particular GPIOs I've been using are on the Audio In connector on the bottom of the Baseboard, which I am using because I have a PCIe x8 ribbon cable, and I don't currently have any of the other connectors on the baseboard. The GPIOs on this Audio In connector currently have a high logic level of 1.8V. From threads like i.MX8 ADC_IN0 pin can't set as GPIO function, I have seen references to dual voltage pads. In particular, SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD is what I'm referring to, which seems to indicate that the pad can output either 1.8V or 3.3V. In my devicetree I have the following code:

&esai0 {
 status = "disabled";
};

&iomuxc {
 pinctrl-0 = <&pinctrl_hog>, <&pinctrl_nstatus>, <&pinctrl_confdone>, <&pinctrl_initdone>, <&pinctrl_nconfig>, <&pinctrl_nce>, <&pinctrl_trgoe>;
 imx8qxp-mek {
  pinctrl_nstatus: nstatus {
   fsl,pins = <
    SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD 0x000514a0
    SC_P_ESAI0_SCKT_LSIO_GPIO0_IO03   0xE4000020 /* gpio 483 nSTATUS  open-drain-input, pull-up, high-drive*/
   >;
   gpios = <&gpio0 3 GPIO_ACTIVE_HIGH>;
  };
  pinctrl_confdone: confdone {
   fsl,pins = <
    SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD 0x000514a0
    SC_P_ESAI0_FST_LSIO_GPIO0_IO01   0xE4000020 /* gpio 481 CONF_DONE open-drain-input, pull-up, high-drive*/
   >;
   gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
  };
  pinctrl_initdone: initdone{
   fsl,pins = <
    SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD 0x000514a0
    SC_P_ESAI0_TX5_RX0_LSIO_GPIO0_IO09  0xE4000020 /* gpio 489 INIT_DONE open-drain-input, pull-up, high-drive*/
   >;
   gpios = <&gpio0 9 GPIO_ACTIVE_HIGH>;
  };
  pinctrl_nconfig: nconfig{
   fsl,pins = <
    SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD 0x000514a0
    SC_P_ESAI0_SCKR_LSIO_GPIO0_IO02   0xE6000020 /* gpio 482 nCONFIG  in-out, pull-up, high-drive*/
   >;
   gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
  };
  pinctrl_nce: nce{
   fsl,pins = <
    SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD 0x000514a0
    SC_P_ESAI0_TX1_LSIO_GPIO0_IO05   0xE6000020 /* gpio 485 nCE   in-out, pull-up, high-drive*/
   >;
   gpios = <&gpio0 5 GPIO_ACTIVE_HIGH>;
  };
  pinctrl_trgoe: trgoe{
   fsl,pins = <
    SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD 0x000514a0
    SC_P_ESAI0_TX2_RX3_LSIO_GPIO0_IO06  0xE6000020 /* gpio 486 TRGOE  in-out, pull-up, high-drive*/
   >;
   gpios = <&gpio0 6 GPIO_ACTIVE_HIGH>;
  };
 };
};‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Following the example from the aforementioned thread, I added in the line "SC_P_COMP_CTL_GPIO_1V8_3V3_GPIORHB_PAD 0x000514a0" for each GPIO. My question is if I can change the output voltage by somehow modifying the hex value at the end of the line.

Any help appreciated. Thanks!

Nolan Z

Re: i.MX8QXP set Dual Voltage Pad Level

igorpadykov — Fri, 27 Mar 2020 01:17:23 GMT

Hi Nolan

>question is if I can change the output voltage by somehow modifying the hex value at the end of the line.

unfortunately not, it can be changed from userspace:

MX8 GPIO - Variscite Wiki

Best regards
igor
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i.MX8QXP set Dual Voltage Pad Level

Re: i.MX8QXP set Dual Voltage Pad Level