Espressif ESP32 Technical Reference Manual page 163

8 SDIO Slave Controller
composed of three words, as shown in Figure 8-4.
• Owner: The allowed operator of the buffer that corresponds to the current linked list. 0: CPU is the
allowed operator; 1: DMA is the allowed operator.
• Eof: End-of-file marker, indicating that this linked-list element is the last element of the data packet.
• Length: The number of valid bytes in the buffer, i.e., the number of bytes that should be accessed from
the buffer for reading/writing.
• Size: The maximum number of available buffers.
• Buffer Address Pointer: The address of the data buffer as seen by the CPU (according to the RAM
address space).
• Next Descriptor Address: The address of the next linked-list element in the CPU RAM address space. If
the current linked list is the last one, the Eof bit should be 1, and the last descriptor address should be 0.
The Slave's linked-list chain is shown in Figure 8-5:
8.3.5 Packet-Sending/-Receiving Procedure
The SDIO Host and Slave devices need to follow specific data transfer procedures to successfully exchange
data over the SDIO interface.
Espressif Systems
Figure 8-4. SDIO Slave DMA Linked List Structure
Figure 8-5. SDIO Slave Linked List
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