# Problem Look at the `TIM7_IRQHandler` function in `stm32f4xx_it.c`. How does it work in conjunction with `SysTick_Handler`? Use the debugger as needed to investigate. # Process The `TIM7_IRQHandler` advances through the `Music` struct array by incrementing the `INDEX` variable. `SysTick_Handler` uses the `INDEX` variable to get the current `Music` struct which it then applies vibrato to. It saves the original pitch of a note by storing the value in `Save_Note`, which `SysTick_Handler` uses in applying vibrato. # Answer ...