IO voltage levels on GPIO pins (not 3V3 but 1V8)

[chat-l18l]

I expected to use GPIO46 and GPIO47 as normal 3V3 GPIO pins.
After some debugging I found out the high level is 1.8 Volt (seems related to power domain for PSRAM?)

I am just mentioning this here so someone can find it. It took me some effort and a scope to figure this one out.
Maybe it should be documented somewhere.

gr,
Edwin

[edwin-oetelaar]

GPIO46/47/48 IO Voltage Requirement

GPIO46, GPIO47, and GPIO48 share the ESP32-P4 VDD_IO_5 bank. This bring-up
firmware claims LDO_VO4 at a fixed 3.3 V before it configures any motor PWM
output. A failed LDO claim blocks motor initialization, so PWM is never driven
from an unknown or 1.8 V bank voltage.

On the Olimex carrier, LDO_VO4 also feeds the microSD IO domain. Do not use
microSD/UHS 1.8 V switching while this bring-up test drives GPIO46/47/48 unless
the pin and power architecture is redesigned.

// GPIO46/47/48 share the ESP32-P4 VDD_IO_5 bank. Keep LDO_VO4 at 3.3 V
// before configuring these external PWM outputs.
#define VDD_IO5_LDO_CHANNEL (4)
#define VDD_IO5_LDO_VOLTAGE_MV (3300)

#include "esp_err.h"
#include "esp_ldo_regulator.h"

static esp_ldo_channel_handle_t s_vdd_io5_ldo = NULL;

static esp_err_t rbt_io_voltage_init(void)
{
    if (s_vdd_io5_ldo != NULL) {
        return ESP_OK;
    }

    const esp_ldo_channel_config_t config = {
        .chan_id = VDD_IO5_LDO_CHANNEL,
        .voltage_mv = VDD_IO5_LDO_VOLTAGE_MV,
        .flags = {
            .adjustable = false,
            .owned_by_hw = false,
        },
    };
    const esp_err_t err = esp_ldo_acquire_channel(&config, &s_vdd_io5_ldo);
    if (err != ESP_OK) {
        ESP_LOGE(TAG,
                 "LDO_VO4 VDD_IO_5 %d mV unavailable: %s",
                 VDD_IO5_LDO_VOLTAGE_MV,
                 esp_err_to_name(err));
        return err;
    }

    ESP_LOGI(TAG,
             "LDO_VO4 VDD_IO_5 fixed at %d mV for GPIO46/47/48",
             VDD_IO5_LDO_VOLTAGE_MV);
    return ESP_OK;
}

Later in your code

    if (rbt_io_voltage_init() != ESP_OK) {
        ESP_LOGE(TAG, "motor PWM bringup blocked: VDD_IO_5 is not at 3.3 V");
        for (;;) {
            vTaskDelay(pdMS_TO_TICKS(1000));
        }
    }