I'm new to the ESP8266, and am trying to compile a very basic program (for now) that writes to the serial port on UART0 using "os_printf". To initialise the UART, I am calling the "uart_init" function, which appears in the SDK documentation in the "user_init" function. Unfortunately, I get a "warning: implicit declaration of function 'uart_init'" and "error: 'BIT_RATE_115200' undeclared (first use in this function)".
I have tried to look around, and example code I see is including "driver/uart.h", which I have copied from my SDK's "driver_lib" example(along with the "uart.c" file) to my local project and tried that, but I then get a lot of errors, including "warning: implicit declaration of function 'uart_div_modify'" and "error: 'RX_BUFF_SIZE' undeclared".
I have built the SDK for Linux using the "esp-open-sdk" at "https://github.com/pfalcon/esp-open-sdk" which uses SDK version 1.5.2. I have tried it with both STANDALONE=y and STANDALONE=n to no avail.
I would have thought that writing to the UART would be one of the simpler things to do, but I am totally stumped! Is there something that I'm missing? Some special incarnation of that make command that will allow it to work?