Other Parts Discussed in Thread: TLIN1431-Q1
- pin mode:
From datasheet, we can see pin mode watchdog will be window mode. If WDT=GND, the total window will be min =32ms, norm=40ms, and max=48ms.
If use norm=40ms as reference, then we can see that window tolerance will be +/-20%. 40ms*(1-20%)=32ms and 40ms*(1+20%)=48ms.
- SPI mode:
Page 34, it says the internal oscillator with a +/-10% accuracy range. But when it calculates the minimum/maximum closed or open window time, it actually uses 10% of total window and another 10% of half window. We can see that 64ms*(1-10%)= 57.6ms, 64ms*(1+10%)=70.4ms. For closed/open window, max = 70.4ms/2=35.2ms, min=57.6ms/2-64ms*10%=28.8ms-6.4ms=22.4ms . this 22.4ms is not from half of the 10% tolerance of 64ms. The half of 10% of 64ms = 28.8ms.
- why do the pin mode and the SPI mode have different tolerance for window time? do they use different method internally?
- the below is the diagram for window timing. We set it to pin mode with 32ms~48ms window timing,
My calculation is that we need send WDI trigger at 28ms+/-4ms, which means that we need change WDI high/low state every 24ms~32ms to keep no watchdog reset. Am I right?
- the graphic showing our plan for WDI trigger event timing diagram based on my understanding.
Please confirm if my calculation and plan for 32ms~48ms pin mode setting is correct. Thanks so lot!
- watchdog won’t activate until the first watchdog pulse is serviced. Does this mean that the chip stays at the force normal mode before the first watchdog pulse is serviced and We don’t need worry about the watchdog reset during SW development before SW is ready to service watchdog pulse?
- how to handle the watchdog service during the CAN reflash? If item 6 answer is yes, then we don’t need worry about watchdog service as long as the flash memory can be erased within watchdog window time 24ms ( our instance safe window 24ms~32ms as above ) .
