L9654 datasheet(56/59 Pages) STMICROELECTRONICS

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Functional description

L9654

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Buffer data values from $0 to $1F are reserved and not transmitted by the "A" Manchester

data sensor. All "A" satellite sensors use values between $020 and $FFF, therefore values

fallen within this range are interpreted by the system software as satellite only data. If a

satellite data is found to be in the range between $00 to $01F the IC asserts the reserved

message error flag or fault code. In case there is no fault condition present, the device

returns to $000.

Data is lost when a data word is written to a full buffer. To alarm the user for this condition

the DL (buffer data lost) flag shall be set.

Table 47. Satellites fault codes definition supporting "B" protocol

Bit D11:0 value

Fault definition

Function

No Faults (FIFO empty value)

Global Fault Codes Definition

(Reported back for CH1 only &

latched only once)

Unassigned

Bad MOSI Bit Count

$3 - $F

Unassigned

$10

High-side Current Limit Exceeded

Channel Fault Codes

$11

Unassigned

$12

SPI Odd Parity Communication error

$13 - $17

Unassigned

$18

Unassigned

$19

Manchester Bit Time Error OR Too Few Bits

$1A

Too Many Bits

$1B

Reserved

$1C

Satellite Communication Parity error

$800 - $FFF

Manchester sensor’s data range D11 shall be

set to 1 by the IC when receiving sensor data.

When reporting faults D11 shall be set

internally by the IC to 0

Manchester Data

As mentioned earlier the L9654 supports "B" Manchester data protocol, the data field for this

protocol can be configured to any number of bits between 8 to 11 bits. Incoming data from

the sensor using "B" protocol shall be right justified by the IC. For example if the incoming

message has only 8 bits in the data filed, the device transmits this message on MISO so that

it occupies bits <7:0> bits 8, 9 and 10 are set to 000.

Too Many Bits and Too Few Bits faults can be calculated based on the number of bits in the

data field. So if we consider the 8 bit "B" protocol example discussed above a message with

9 bits in the data field should set the too many bits fault flag, on the other hand a message

with 7 bits in the data field should set the too few bits fault flag. When the L9654 is

configured to use a the Manchester "B" protocol, the device set SPI MOSI D11 to 0 when

reporting fault data and to 1 when reporting satellite data. This operation should allow both

sensors "A" based or "B" based to use the same fault codes.

Upon power on, after a reset or POR conditions the MISO data is initialized as follows:



CH1 returns to MCR configuration in report mode with parity bit set accordingly



CH2 returns $E000.

L9654 Datasheet(PDF) 56 Page - STMicroelectronics

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