ESP32 Forum

Posted: **Mon Nov 29, 2021 9:57 pm**

Hi,

I want to dive a little bit deeper into the esp-idf to program the ULP of the ESP32. As a first start I try to implement a simple blinking example for the ULP, but I struggle with the default analog configuration of the RTC pins.

I have checked the Technical Reference Manual (https://www.espressif.com/sites/default ... ual_en.pdf) and found the RTC_MUX Pin list on page 58 and I also look at the RTC driver of the esp-idf. There I found the following structure that is used for the initialization of the RTC GPIO:

Code: Select all

const rtc_gpio_desc_t rtc_gpio_desc[SOC_GPIO_PIN_COUNT] = {
    {RTC_IO_TOUCH_PAD1_REG, RTC_IO_TOUCH_PAD1_MUX_SEL_M, RTC_IO_TOUCH_PAD1_FUN_SEL_S, RTC_IO_TOUCH_PAD1_FUN_IE_M, RTC_IO_TOUCH_PAD1_RUE_M, RTC_IO_TOUCH_PAD1_RDE_M, RTC_IO_TOUCH_PAD1_SLP_SEL_M, RTC_IO_TOUCH_PAD1_SLP_IE_M, RTC_IO_TOUCH_PAD1_HOLD_M, RTC_CNTL_TOUCH_PAD1_HOLD_FORCE_M, RTC_IO_TOUCH_PAD1_DRV_V, RTC_IO_TOUCH_PAD1_DRV_S, RTCIO_GPIO0_CHANNEL}, //0
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1},                                                                                                                                            //1
    {RTC_IO_TOUCH_PAD2_REG, RTC_IO_TOUCH_PAD2_MUX_SEL_M, RTC_IO_TOUCH_PAD2_FUN_SEL_S, RTC_IO_TOUCH_PAD2_FUN_IE_M, RTC_IO_TOUCH_PAD2_RUE_M, RTC_IO_TOUCH_PAD2_RDE_M, RTC_IO_TOUCH_PAD2_SLP_SEL_M, RTC_IO_TOUCH_PAD2_SLP_IE_M, RTC_IO_TOUCH_PAD2_HOLD_M, RTC_CNTL_TOUCH_PAD2_HOLD_FORCE_M, RTC_IO_TOUCH_PAD2_DRV_V, RTC_IO_TOUCH_PAD2_DRV_S, RTCIO_GPIO2_CHANNEL}, //2
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1},                                                                                                                                            //3
    {RTC_IO_TOUCH_PAD0_REG, RTC_IO_TOUCH_PAD0_MUX_SEL_M, RTC_IO_TOUCH_PAD0_FUN_SEL_S, RTC_IO_TOUCH_PAD0_FUN_IE_M, RTC_IO_TOUCH_PAD0_RUE_M, RTC_IO_TOUCH_PAD0_RDE_M, RTC_IO_TOUCH_PAD0_SLP_SEL_M, RTC_IO_TOUCH_PAD0_SLP_IE_M, RTC_IO_TOUCH_PAD0_HOLD_M,  RTC_CNTL_TOUCH_PAD0_HOLD_FORCE_M, RTC_IO_TOUCH_PAD0_DRV_V, RTC_IO_TOUCH_PAD0_DRV_S, RTCIO_GPIO4_CHANNEL}, //4
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1},                                                                                                                                            //5
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1},

I don´t understand where this information comes from. Does the datasheet give any more details about the default analog functions for the RTC pins that are used to build up this structure?

ESP32 Forum

Where do I find the default analog function for the RTC GPIO?

Where do I find the default analog function for the RTC GPIO?