AN3324 datasheet(21/37 Pages) STMICROELECTRONICS

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AN3324

Module software requirements for non applicative peripherals

Doc ID 18311 Rev 2

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3.11

Temperature sensors

There are two temperature sensors: temperature sensor 0 mapped to ADC_0 channel 15

and temperature sensor 1 mapped to ADC_1 channel 15.

During power up, user software has to read temperature sensors and verify that the values

are similar as means of assessing the functionality of the sensors.

Note:

In case of a fault, software must trigger the appropriate reaction. To set a proper threshold

the customer must consider that the maximum operating junction temperature is 150 °C, for

details please refer to SPC56EL60 datasheet (see B.1: Reference documents in Appendix

B) and the temperature sensor accuracy is 10 °C.

It is mandatory to read the 2 sensors synchronously or with a reduced time interval.

Note:

It is important to note that the ADC is part of the temperature measuring safety integrity

function, and it is therefore required that the BIST of the ADC must be executed once after

the boot even if the ADC is not in application use.

3.12

Software Watchdog Timer (SWT)

The SWT has to be enabled and configuration registers have to be hard-locked against

manipulation.

The time window settings of the SWT have to be set to a value less than the PST(e) (process

safety time). Detection latency is smaller than process safety time.

Before the safety function is executed, the software must verify that the SWT is enabled by

reading the SWT control register (SWT_CR).

Note:

To enable the SWT and to hard-lock the configuration register, the WEN and HLK flags of

the SWT control register (SWT_CR) must be asserted. The timeout register (SWT_TO)

must contain a 32-bit value that represents a timeout less than the process safety time.

Caution:

SWT must be refreshed with a timeline that depends by setted timeout (SWT_TO value).

For this reason it should be configured properly when MCU execute uninterruptible tasks

(see Section 3.10.1: Array integrity self check procedure) to avoid application reset.

PST is strictly application dependant.

AN3324 Datasheet(PDF) 21 Page - STMicroelectronics