L9662 datasheet(62/80 Pages) STMICROELECTRONICS

62 / 80 page

Functional description

L9662

62/80

DocID028325 Rev 1

The ASIC shall supports a Satellite Protocol-B, which is based on Bosch sensors

PAS3/PAS4 protocols. The default for the device is to perform parity decoding on all

messages. The device has the option not to perform the CRC decoding and pass the

satellite message, excluding the 2 start bits, over the MISO. Parity decoding can be

disabled/enabled by writing to the appropriate bit in the CCR register.

For the parity mode the error detection code used for processing the message is even. If the

device is in CRC mode it will process all incoming messages and report an error via SPI2 in

case of a parity mismatch. The parity check is performed after a complete message is

received and, in case of an error, the device sets a fault code in the SR word.

The message data sent over SPI2 is MSB first.

Protocol C: PSI5 mode - parity protocol

The data received from satellite receiver block has to be decoded in the digital block. The

data received from the satellite is LSB first followed by the Parity bit. The protocol format is

defined below for the 4 different message lengths.

Figure 18. PSI5 – parity satellite protocol

When the PSI5 parity protocol is selected, the ASIC performs a parity check then passes the

satellite message, excluding the 2 start bits and parity bit over the MISO on SPI2. For parity

protocol, the error detection code used for processing the message is even. The parity

check is performed and in case of an error, the device sets a fault code in the SR word.

When commanded, the message data excluding the start bits and parity bit is sent

over SPI2 MSB first.

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