on the esp32 datasheet pg 28, it says "each digital gpio can be configd with pullups or pulldowns"
using the arduino esp32 build, i've tested all pins and found the following work with INPUT_PULLUP: 14, 16, 17, 18, 19, 21, 22, 23 as expectedThere are several kinds of GPIOs: digital only GPIOs, analog enabled GPIOs, capacitive touch enabled GPIOs, etc.
Analog enabled GPIOs can be configured as digital GPIOs. Capacitive touch enabled GPIOs can be configured
as digital GPIOs.
Each digital enabled GPIO can be configured to internal pull-up or pull-down, or set to high impedance.
but these do not: 13, 25, 26, 27, 32, 33 . Overall pin output/input mode capability is working. i noted all are ADC-capable pins (but pin 14 is ADC too and does work??)
relatedly, the pins with 'straps': 0, 2, 4, 5, 12, 15 also don't seem to have the ability to disable/change the pullup/down. the datasheets sort of implies that the way strapping is done is by activating the default pd/pu on boot (esp_chip_pin_list.pdf pg 4) but it seems more like the 'straps' are not just default activation of the optional pu/pd but actual 'permanent resistors'.
Q. can someone please clarify/verify that not all pins have pullup capability? also, that the 'straps' are non-configurable?