I want to send some data via UART directly to DMA without interruption. To solve this problem I use a custom FIFO stack from which the DMA feeds itself using its DMA interrupt-routine.
The stack is filled with data by the UART interrupt routine (if data arrives via uart). Unfortunately sometimes both interrupts DMA and UART occur simultaneously which means one interrupt routine has not finished its stack operation while the other routine starts a new one.
I was thinking to define a kind of USER – INTERRUPT of higher priority than UART and DMA to execute all stack operations if requested. Does anybody know how to implement an user interrupt, which can be fired from user code ?