Why is MTDI of ESP32-PICO-KIT pulled high?

[DurandA]

While reading the schematic of the ESP32-PICO-KIT (https://dl.espressif.com/dl/schematics/ ... ematic.pdf), I noticed that MTDI is held high using a 10k resistor (R23).

However, the ESP32-PICO-D4 datasheet (https://www.espressif.com/sites/default ... eet_en.pdf) states:

The operating voltage of ESP32-PICO-D4’s integrated external SPI flash is 3.3 V. Therefore, the strapping pin MTDIshould hold bit ”0” during the module power-on reset.

[boarchuz]

Note the "NC".

I'm not sure why though. Is it possible for someone to connect their own external flash, that might be 1.8V? Or maybe it's to future-proof the board layout in case of a Pico with 1.8V internal flash? Maybe the Pico D4 internal flash voltage wasn't finalised when this board was being designed?

[ESP_Sprite]

Probably just to have options, either for production or for the end user. Out HW team tends to put NC components in places where it might make sense that someone may possibly want one.