DocID024648 Rev 4

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AIS1200PS

Mechanical and electrical specifications

2.4.4

Initialization

After each power-on or undervoltage reset, the sensor performs an internal initialization

which is divided into three phases.

Figure 6. Initialization of the sensor

ID blocks and data blocks are sent in an alternating sequence, 3 times each. The block

identifiers are used for numbering of the following data nibbles. After any power-on or

undervoltage reset, the internal logic starts up with an initialization program.

During the first initialization phase, no data is transmitted and the ECU can perform a

connectivity test.

During the second initialization phase, the sensor transmits sensor and application-specific

information to the ECU. During the third initialization phase, the sensor transmits “Sensor

Ready”, “Sensor Defect” or other optional status data. If the sensor is defective, it will

continue to send the “sensor defect” messages and other optional status data until it is

powered off. The sensor status information must consist of data words out of data range 2

and 3. Usage of sensor output signal data words out of data range 1 is not allowed during

initialization phases II and III.

If the initialization is finished successfully, the sensor goes into run mode and starts

transmitting sensor signal data or optional status data until it is switched off or an internal

error is detected.

In the AIS1200PS, phase 1 has a typical duration of 121 ms, and phase 2 of 43 ms. Phase

3 duration may vary, depending on the number of iterations needed to pass the self-test

routine.

If the self-test fails, the self-test routine is repeated until it passes, up to 5 times. If the self-

test does not pass after 5 attempts, it will transmit a message of sensor failure.

After phase 3 is passed successfully, the sensor goes into run mode and starts transmitting

sensor signal data.

The actual duration of all phases depends on the oscillator period, which has a tolerance of

±5% (see Table 5).

For the AIS1200PS device, k = 3

121ms

448

s

43ms