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WT21-A-HCI

BLUETOOTH HCI MODULE

Unspecified 

7.2

SDIO Interface

This is a host interface which allows a Secure Digital Input Output(SDIO) host to gain access to

the internals of the chip. It provides all defined slave modes (SPI, SD 1bit, SD 4bit), but not SD

host function.

The function provided includes generating responses to each command in hardware and

implementing the state machines defined in the SDIO specification. Within the various modes of

operation, it provides initialisation functions (cmds 0, 3, 5, 7, 15, 59) and two other functions:



Function 1 provides Bluetooth type A support, and follows that specification



Function 2 provides generic register access(cmd52 (byte read/write))

For more information, see the following specifications:



SD Specifications Part 1 Physical Layer Specification v.1.10



SD Specification Part E1 SDIO Specification v.1.10



SDIO Card Part E2 Type-A Specification for Bluetooth v.1.00

7.2.1 SDIO/CSPI Deep-Sleep Control Schemes

This is the lowest power mode, where the processor, the internal reference (fast) clock, and

much of the digital and analogue hardware are shut down. To support this power consumption

reduction solution and to prevent any errors arising on the SDIO host interface there are two

Deep-Sleep control schemes.



Scheme 1: The host retransmits any packets that Bluecore was unable to receive

as a result of being in Deep-Sleep



Scheme 2: Introduces additional signaling to prevent the need for retransmissions

During Deep-Sleep the internal reference clock is turned off. However, the host transport

protocols (SD/UART/CSPI) are driven from the SDIO clock and so continue to function during

Deep-Sleep, enabling access to the function 0 interface, but not the function 1 interface.

7.2.2 Retransmission

Bluecore enters Deep-Sleep whenever it becomes idle after which time, when the host transmits

a message on function 1 an illegal command error will be signaled. The activity that this

initiates on the SDIO Interface provokes Bluecore into wakeup after which the host re-transmits

the original message.

Bluecore will wait for a configurable period of time before re-entering Deep-Sleep, thus ensuring

that the original packet is sent/received on retransmission. This control scheme is the default

mode of operation.

7.2.3 Signaling

Signalling between the host and Bluecore enables host control over Bluecore Deep-Sleep mode.

Consequently the host is aware of when it is appropriate to send Bluecore HCI traffic over

function 1.

The signals used by this scheme are Host wakeup and Ready status interrupt select,

implemented as register bit in the vendor unique area of function 0.

Bluegiga Technologies Oy

Page 26 of 56

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