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AM2434: RTI features

Tony Tang
Mastermind 28112 points
Part Number: AM2434

Tool/software:

#1. What is mean of the CAUTION Notes? only as a Digital Windowed Watchdog? can only be Watchdog?

#2. What is mean of Real time interrupt functionality, different with interrupt functionality?

#3. How to understand not support Periodic interrupt? can't auto reload period value?

#4. About the time out interrupt, When it trigger interrupt in different window size?

#5. Take 100 Window,  When it generate interrupt, then how about 50%?

#6. in my customer use case, configured as 1000ms interrupt interval, but it is about 754ms interval from test result.

#6. Also captured RTI8 registers if needed, I checked not find big problem, just the period is (2+1)*2^13/25MHz, which is about 960ms. 

  • 0 in reply to Tony Tang
    TI__Mastermind 39521 points

    Hello Tony,

    Sorry for delayed replies and thread seems assigned to wrong Engineer .

    Tony Tang said:
    in my customer use case, configured as 1000ms interrupt interval, but it is about 754ms interval from test result.

    I assume that for the first time WDT is configured to around 750msec and loaded the example 

    Next, again changing the WDT time expired to 1000msec and loaded the example from CCS.

    Can you please confirm for every WDT expiration change did you perform Warm Reset / POR ?

    Since , the watchdog expiration configures one time only.

    And, I have seen the above code where customers do the Software Reset in the watchdog ISR routine and this is not correct procedure.

    If core in exception, any IRQ's will not trigger. So, device may not Reset.

    To avoid this problem, we need to go with AUTO Reset the SOC when the watchdog expires.

    Please look at the FAQ link for AUTO RESET SOC when the watchdog expires.

    https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1283237/faq-am64x-am62x-how-to-reset-the-soc-when-wdt-timer-expires-in-am64x-and-am62x

    Tony Tang said:
    Take 100 Window,  When it generate interrupt, then how about 50%?
    Tony Tang said:

    #4. About the time out interrupt, When it trigger interrupt in different window size?

    If you configure the 100% window, then you need to feed Watchdog keys from 0 to 100% window time then WDT restart the count freshly .

    If you don't feed keys before the WDT expiration time, then exactly WDT will generate an interrupt after the expiration time.

    If you configure the 50% window, then you need to feed Watchdog keys from 50 to 100% window time.

    If you feed keys before the 50 % window WDT expiration time, this is not the correct method to feed watchdog keys.

    So, exactly WDT will generate an interrupt .

    If you feed keys in between the 50 % to 100% window, WDT expiration time will start freshly and this is correct method .

    If you don't feed keys in between the 50 % to 100% window, then WDT interrupts its exactly at expiration time .

    Tony Tang said:
    What is mean of the CAUTION Notes? only as a Digital Windowed Watchdog? can only be Watchdog?

    If you configure the window size as 100%, then the watchdog can acts as like a normal watchdog.So, the user can feed Watchdog keys the between 0 to 100% window and there are no issues.

    If user configures other than 100%window size, then users need to give keys in between windows only.

    This is called digital windowed watchdog.

    Tony Tang said:

    #3. How to understand not support Periodic interrupt? can't auto reload period value?

    Yes, this is not supported ... Once the time expires to particular value, then there is no register to to load the the count value to trigger the next time interrupt.

    Tony Tang said:
    What is mean of Real time interrupt functionality, different with interrupt functionality?

    I am not sure what is real time interrupt functionality .

    As per TRM, this real time functions mainly belong to OSEK automotive specific applications.

    Regards,

    Anil.