Resolved! I want to use DMA for UART receive. How do I generate an interrupt using the HAL for idle line? The UART Callbacks are disabled in the HAL when you use DMA. And it does not look like there is a call back for idle_line in the HAL.
When I setup the UART i activated both DMA TX and RX, and I turned on the UART Interrupt in the MX program. Looking at the code in stm32f4xx_hal_uart.h Around line 680/* Callbacks Register/UnRegister functions ***********************************/#if ...