STA2500D datasheet(36/57 Pages) STMICROELECTRONICS

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General specification

STA2500D

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Doc ID 16067 Rev 1

BT_HOST_WAKEUP to ‘1’ in order to warm the Host and traffic starts when the Host

puts BT_UART_CTS to low. This is illustrated in Figure 12.

Autonomous wake-up with communication (i.e. initiated by the STA2500D)

The STA2500D first asks the Host to restart the system clock by setting

BT_CLK_REQ_OUT_1 to ‘1’.

When the clock is available, the STA2500D requests traffic by asserting

HOST_WAKEUP high. Then either it puts BT_UART_RTS low to start traffic exchange

directly or it waits for the Host to first assert BT_WAKEUP high. The selection in

between the two behaviours is done by a SW parameter in the Parameter File.

An autonomous wake-up without communication (i.e. initiated by the STA2500D)

The STA2500D asks the Host to restart the system clock by setting

BT_CLK_REQ_OUT_1 to ‘1’. The UART signals are not changing.

Figure 11.

Entering deep sleep mode, pending data on UART interface, through

UART with handshake

Host puts BT_WAKEUP low. BT Controller notices it. But as there is pending traffic to

be send to Host, it keeps HOST_WAKEUP high as long as needed for up-transmission

and then de-asserts HOST_WAKEUP, telling the Host there is nothing more to

transmit.

BT Controller puts UART_RTS high to set “flow off”. This is done in fixed number of

instructions.

Then BT Controller puts CLK_REQ_OUT_1 to ‘0’, telling the Host it can cut the clock.

This is done in fixed number of instructions.

There is no clock, BT is in Deep Sleep mode.

REF_CLK _IN

CLK _REQ _O UT_1

BT_WAKEUP

UART_RTS

HOST_WAKEUP

REF_CLK _IN

CLK _REQ _O UT_1

BT_WAKEUP

UART_RTS

HOST_WAKEUP

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