A direct memory access (DMA) controller, an electronic device that uses the DMA controller, and a method of operating the DMA controller are provided. The DMA controller is configured to access a memory that contains a secure area and a non-secure area. The method of operating the DMA controller includes the following steps: searching for a DMA channel that is in an idle state in the DMA controller; setting a register value of a mode register of the DMA channel such that the DMA channel operates in a secure mode; setting a memory address register and a byte count register of the DMA channel; and controlling the DMA channel to transfer data based on the memory address register and the byte count register.