36.4.2.1 SQI Transfer Modes

The SQI module operates in three transfer modes: DMA, PIO, and XIP. As mentioned earlier, DMA and PIO modes are typically used to transfer data, whereas XIP mode is used to execute the code out of the attached serial Flash memory space. DMA mode uses the internal DMA engine and linked-list type of structures to transfer data between source and destination memory spaces, making it a little more automated, resulting in less software overhead and CPU intervention. DMA mode can be considered as a high throughput data transfer mode. In PIO mode, the CPU can access the contents of the attached serial memory device through the SQI transmit data and receive data registers with status and interrupt flag assistance.