STA2500D datasheet(35/57 Pages) STMICROELECTRONICS

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STA2500D

General specification

Doc ID 16067 Rev 1

35/57

Figure 10.

Deep sleep mode entry and wake-up through H4 SPI

Deep sleep mode entry and wake-up through H4 UART or H4 SPI with

handshake

This method is supported by both H4 UART and H4 SPI. The description below is for H4

UART.

It requires BT_CLK_REQ_OUT_1, BT_WAKEUP and BT_HOST_WAKEUP. The

BT_WAKEUP is used as wake-up signal from the Host, the BT_CLK_REQ_OUT_1 requires

the clock from the Host and BT_HOST_WAKEUP is used as a wake-up signal from the

Bluetooth Controller.

●

Deep sleep mode entry

The Host tells the STA2500D that it can go in Deep Sleep mode by forcing the

BT_WAKEUP of the STA2500D to ‘0’. The STA2500D decides to go in Deep Sleep

mode, or not, depending on its scheduled activity and on the number of events or data

packets to be sent to the Host. In case it decides to go in Deep Sleep mode, it asserts

BT_CLK_REQ_OUT_1 low to tell the Host that it does not need the clock anymore. On

the contrary, if it still wants the interface active for up-transmission, it keeps

BT_HOST_WAKEUP to ‘1’ as long as needed before de-asserting

BT_CLK_REQ_OUT_1. This is illustrated in Figure 11.

●

Deep sleep mode wake-up

The wake-up procedure can be initiated by the Host or by the STA2500D. In the latter

case, it can be with or without communication, depending if there are data to be

transmitted to the Host.

Wake-up initiated by the Host

The Host sets the BT_WAKEUP pin of the STA2500D to ‘1’. Then the STA2500D asks

the Host to restart the system clock by setting BT_CLK_REQ_OUT_1 to ‘1’. When the

clock is available and stable, the STA2500D puts BT_UART_RTS low to allow

communication. In case the STA2500D wants to send events to the Host, it then puts

Active

Sleep Mode

Mode

SPI off

SPI on

HOST_WAKEUP=‘ 1’ or ‘ 0’

CLK_REQ_OUT_1 = ‘ A’ :

Active

high/low

‘ P’ :

Passive

low/high

Active

Sleep Mode

Host:

BT_WAKEUP=‘0’

SPI off

Host:

BT_WAKEUP=‘1’

BT Controller:SPI_INT=‘ 1’

HOST_WAKEUP=‘ 0’

Host:

BT_WAKEUP=‘1’

AND

BT Controller: CLK_REQ_OUT_1=‘ A ’

Active

Sleep Mode

Deep Sleep

Mode

SPI off

SPI on

HOST_WAKEUP =‘ 1’ or ‘ 0’

CLK_REQ_OUT_1 = ‘ A’ :

Active

high/low

‘ P’ :

Passive

low/high

Active

Sleep Mode

Host:

BT_WAKEUP=‘0’

SPI off

Host:

BT_WAKEUP=‘1’

BT Controller: BT_SPI_INT =‘ 1 ’

HOST_WAKEUP=‘ 0’

Host:

BT_WAKEUP=‘1’

AND

BT Controller:BT_CLK_ REQ_OUT_1=‘ A’

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