ESP32 Forum

Posted: **Tue Jun 25, 2019 1:53 am**

I have a project where i am using UART_NUM_2. I have this running just fine using the ESP-WROOM-32 module.
I received my ESP32-PICO-KIT today, and just to test that it was good i downloaded the same code to it.
When it booted it panic'ed. I started commenting out lines of code to narrow it down and discovered that this line is the culprit.

Code: Select all

uart_set_pin(UART_NUM_2, 17, 16, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);

If i change 17 & 16 to say 4 & 5 it does not panic.

According to the ESP32-PICO-D4 data sheet GPIO 17 & 16 are free for GPIO, so why does it work ok on the ESP-WROOM-32 module but panic on the ESP32-PICO-KIT v4.1 ?

I am using ESP-IDF v3.2-rc

: gpio.png (22.52 KiB) Viewed 2956 times

Posted: **Tue Jun 25, 2019 2:07 am**

They are not free for random use. As the notes section of that data sheet states: "Pins IO16, IO17, CMD, CLK, SD0 and SD1 are used for connecting the embedded flash, and are not recommended for other uses. For details, please see Section 6 Schematics."

Posted: **Tue Jun 25, 2019 3:39 am**

LOL, had i went down one more page in the data sheet I would seen that.

Out of curiosity. I wonder why they even list the following when they cannot be used as such.
IO16 = GPIO16, HS1_DATA4, U2RXD, EMAC_CLK_OUT
IO17 = GPIO17, HS1_DATA5, U2TXD, EMAC_CLK_OUT_180

IMHO they should have these listed as
IO16 = FLASH_CS
IO17 = FLASH SO

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