Atmega8535 project

[ITstreet1]

What pins I can use for Software Serial on this MCU? As far as I know, for RX it must be an interrupt pin. So it can be PD2, PD3, or PB2. For TX can be anyone. Am I right?

[MCUdude]

As far as I know, for RX it must be an interrupt pin. So it can be PD2, PD3, or PB2. For TX can be anyone. Am I right?

Correct!

[ITstreet1]

I made the board. The bootloader goes fine. I can upload a sketch, and blink an LED. But, when I try to upload a barebone example with only Wire.h included, I get this error:

C:\Users----\Documents\Arduino\libraries\Wire\Wire.cpp: In member function 'void TwoWire::begin()': C:\Users----\Documents\Arduino\libraries\Wire\Wire.cpp:62:3: error: 'DIDR0' was not declared in this scope DIDR0 &= 0xCF; ^~~~~ C:\Users----\Documents\Arduino\libraries\Wire\Wire.cpp:62:3: note: suggested alternative: 'DDA0' DIDR0 &= 0xCF; ^~~~~ DDA0 Multiple libraries were found for "Wire.h" Used: C:\Users----\Documents\Arduino\libraries\Wire Not used: C:\Users----\AppData\Local\Arduino15\packages\MightyCore\hardware\avr\2.1.3\libraries\Wire Multiple libraries were found for "SPI.h" Used: C:\Users----\Documents\Arduino\libraries\SPI Not used: C:\Users----\AppData\Local\Arduino15\packages\MightyCore\hardware\avr\2.1.3\libraries\SPI exit status 1 Error compiling for board ATmega8535.

[MCUdude]

Your error message clearly shows the issue:

Multiple libraries were found for "Wire.h" Used: C:\Users----\Documents\Arduino\libraries\Wire Not used: C:\Users----\AppData\Local\Arduino15\packages\MightyCore\hardware\avr\2.1.3\libraries\Wire Multiple libraries were found for "SPI.h" Used: C:\Users----\Documents\Arduino\libraries\SPI Not used: C:\Users----\AppData\Local\Arduino15\packages\MightyCore\hardware\avr\2.1.3\libraries\SPI exit status 1

You will have to either rename or remove the SPI and Wire libraries located in C:\Users----\Documents\Arduino\libraries. These are some custom ones you have installed that interfere with the built-in ones.

[ITstreet1]

I missed that. But this error never came up when compiling for other MCUs. Say ESP8266, ESP32, Uno, etc. The reason I didn't even notice this error as I should. This lib is there for a while, never making problems.

[MCUdude]

But this error never came up when compiling for other MCUs. Say ESP8266, ESP32, Uno, etc.

It may be because it has architectures=avr in the library.properties file. If the library is written for a UNO, there's your problem. The ATmega8535 is also an AVR, but the library has not been developed for it specifically.