I have a multi-file project and in main.c I have a global array to store a string of characters. In my main function I call function i2c_send from another file(i2c.c) that sends this string over i2c. Naturally, my i2c isr is in i2c.c, and naturally it needs to write the string into the i2c buffer for the transmission to begin. Since I can't pass the string into the isr as a parameter, the string within i2c has to be a global. Short of doing a strcpy in my i2c_send function, what can I do to let my isr refer to the string in main.c and copy that into the i2c buffer?