AN3324 datasheet(24/37 Pages) STMICROELECTRONICS

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AN3324

Module software requirements for applicative peripherals

Doc ID 18311 Rev 2

24/37

Module software requirements for applicative

peripherals

The ADC, due to its analog part, is the only application peripheral that requires additional

hardware bist after the boot.

This module is part of the temperature measuring safety integrity function, and it is therefore

required that the HWBIST functions are executed once after the boot (please refer to

AN3077, see B.1: Reference documents in Appendix B).

4.1

Analog to Digital Converter (ADC)

After boot and before starting execution of any safety function, user has to execute ADC

HWBIST functions to check if the ADC is functioning correctly and to increase the diagnostic

coverage.

4.1.1

Self test algorithms

Three types of self testing algorithms have been implemented inside ADC analog.

●

Supply self test: Algorithm S.

It includes the conversion of the ADC internal bandgap voltage, ADC supply voltage,

and ADC reference voltage. It includes a sequence of 3 test conversions (steps). The

supply test conversions must be an atomic operation (no functional conversions

interleaved).

●

Resistive-Capacitive self test: Algorithm RC.

It includes a sequence of 19 test conversions (steps) by setting the ADC internal

resistive digital-to-analog converter (DAC).

●

Capacitive self test: Algorithm C.

It includes a sequence of 17 test conversions (steps) by setting the capacitive elements

comprising the sampling capacitor/ capacitive DAC.

The ADC implements an additional test channel dedicated for self testing. It also provides

signals to schedule self testing algorithms using configuration registers, monitors the

converted data using analog watchdog registers, flags the error to FCCU in case some

failure occurs in any of the algorithms.

Note:

User can execute these tests in CPU Mode (One shot or Scan Mode) and in CTU Mode

(see Figure 9: ADC self test in CPU mode using one shot sequence).

AN3324 Datasheet(PDF) 24 Page - STMicroelectronics