I am using https://github.com/me-no-dev/ESPAsyncWebServer on an ESP32-EVB in a project that also uses the following library to read Wiegand Cards https://github.com/paulo-raca/YetAnotherArduinoWiegandLibrary.
I investigated and found that after accessing/refreshing the web interface or navigating to another page the first card reading is also an error.
Whenever I comment the Server Routine, so basically running the project without an HTTP server, the Wiegand cards are read perfectly.
So I came to the conclusion that after each Server "initialization " the first card reading is always an error.
The input pins that I've tried are GPIO 13,14,15 and 17, because others are, well, unavailable.
But looking at the ESP32 docs: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/gpio.html these pins have other uses:
GPIO13 - ADC2_CH4
GPIO14 - ADC2_CH6
GPIO15 - ADC2_CH3
GPIO17 - SPI0/1
SPI0/1: GPIO6-11 and GPIO16-17 are usually connected to the SPI flash and PSRAM integrated on the module and therefore should not be used for other purposes.
ADC2: ADC2 pins cannot be used when Wi-Fi is used.
And this got me thinking that I get an error when there is network communications and that maybe this is a GPIO related issue.
The problem is that I only have ESP32-EVB available to me right now and I can't test with something else.
I will get my hands on a "simpler" ESP32 board with more free GPIOs and test this, but in the meantime I would like some confirmation or some thoughts on this matter.
What about GPI pins like GPI 34, 35, 36, 37, 38 and 39 ?
GPI 34 - BTN1
GPI 35 - CAN-RX
GPI 36 - SENSOR_VP/ADC_H/ADC1_CH0/RTC_GPIO/U1RXD
GPI 37 - Couldn't find it in the schematics
GPI 38 - Couldn't find it in the schematics
GPI 39 - SENSOR_VN/ADC1_CH3/ADC_H/RTC_GPIO3/IR_RECEIVE
Also, what about the ESP32-POE ? Does it really have more free pins, because it doesn't look like that. Also if you power the ESP32-POE using POE, what voltage will the GPIO have ? 3.3V or 5V ?
ESP32-GATEWAY, ESP32-POE, ESP32-POE-ISO have more free pins compared to ESP32-EVB. The point of ESP32-EVB was to leave as little free pins as possible to demonstrate more of the ESP32 chip capabilities. It was our first ESP32 release.