MPC5746C fails to enter STANDBY mode

[1045302770]

I found that the MPC5746C fails to enter STANDBY mode while the WKPU registers of a wakeup pad are configured as follows:

1) WKPU_WISR, WKPU_WRER, WKPU_WIREER, WKPU_WIFFER of the wakeup pad is set to '0'

2) WKPU_WIPER of the wakeup pad is set to '1'

3) Please notice that this wakeup pad is a FLEXCAN RXD pad, and before the mode transition request, no Rx or Tx interrupt was generated 

4) I am sure that there is no interrupt and wakeup event of other wakeup pads

However, I tried to set WKPU_WIPER of the wakeup pad  to '0' , and other conditions keep the same as above, it enters STANDBY mode normally.

I want to know why the configuraion of WKPU_WIPER have a influence on the mode entry process. 

[lukaszadrapa]

Hi,

if disabling of internal pull resistor solves this problem, I would check the voltage level on this pin by oscilloscope. It looks like there's no valid voltage level, so the output may be switching between '0' and '1'. Stronger external pull resistor may be needed to ensure appropriate voltage level.

Regards,

Lukas