L9654 datasheet(34/59 Pages) STMICROELECTRONICS

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Functional description

L9654

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DocID14218 Rev 3

Bit D9 and bit D8 are used to set the period of pulse stretch timer.

The device have 8 independent timers. Either a valid arming signal or a SPI deployment

command is able to start the pulse stretch timer. These bits sets the timer duration. These

values default to ‘00’ after a POR event.

Table 17. Pulse stretch timer table

Bit D9

Bit D8

Stretch period (ms)

7.5

Bit D7 through bit D0 are used for a soft reset sequence. The soft reset for the deployment

driver is achieved by writing $AA and $55 within two subsequent 16-bit SPI transmissions. If

the sequence is broken, the processor is required to re-transmit the sequence.

L9654 does not reset if the sequence is not completed within two subsequent 16-bit SPI

transmissions. This soft reset function is available only to deployment drivers.

When soft reset command is received, the device resets its deployment driver’s internal

logic and timer. The effects of soft reset to the deployment driver is the same as the one of

POR event, except for MISO response.

During a deployment, soft reset sequence is ignored.

4.11.3

Deployment driver command mode

Command Mode message is defined as shown below.

Table 18. MOSI command mode message definition

Bit

State

Description

D15

Mode bits

D14

D13

Odd Parity

D12

Don’t Care

D11

Don’t Care

D10

Don’t Care

Channel 7 Idle (default)

Deploy Channel 7

Channel 6 Idle (default)

Deploy Channel 6

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