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FS6500 Long duration timer

Question asked by Tibor Csecsei on May 3, 2019
Latest reply on May 12, 2019 by G.w. Sun

We are using our FS6500 (exactly MC33FS6520CAE) SBC for our automotive project.
IO and CAN wake-up sources can be configurable and working as we expect, but we cannot set "LONG_DURATION_TIMER" register by SPI. I mean all register can be changed by our SPI commands (incl. INIT_VREG, INIT_WU and LDT_AFTER_RUN, LDT_WAKE_UP and other registers too), but when we try to write 0x66 to register #6, it stays 0x04.

If we try to modify it in INIT state, we get SPI_REQ error as it have to be, but when we try to write it in NORMAL state, we do not get any error back. After that (when we read the value back) it stays 0x04 in all cases. We tried Function1, Function2, Function4 with configured 10-20-32 seconds, but when Function1 or 2 is selected, the counter does not starts to count and the SBC never enters to LPOFF. When Function4 is selected and we set SBC to LPOFF mode, 5V output switches off, but never wakes up (only after power cycle).

We tried to set LDT_WAKE_UP_1 to 10 and others are 0 and set LDT_WAKE_UP_3 to 10 and others to 0 too.

We are using this IC in our other project, but the circuit differs (both are made by our partners).


Thank you for your support.