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

Kampino
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Joined: Fri Jan 08, 2021 12:19 pm

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

Postby Kampino » 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?

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