Other Parts Discussed in Thread: TMS320F28335
I have few circuit boards with TMS320F28335 on it. Some of them work correctly, as expected (figure 1), but couple set XRS pin to low level after power up for a short-term (figure 2-4). It seems like watchdog reset, but only 4-5 clock pulses preceded to this (figure 5) and watchdog was disabled by software (program runs from FLASH, it is same for all boards). I tried to compare supply voltages on different boards and it looks identical on boards with reset on start (figure 6) and without it (figure 7).
Figures 8 and 9 show XSR level and clocks from external generator (ASEMB-20.000MHZ-XY) to the board with reset and without it respectively.
May you explain me what kind of reset occurs during power up and what I have to do to discard it?
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9