topic Re: FXTH87 STOP1 RTI Error in Sensors

FXTH87 STOP1 RTI Error

mhusthutchinson — Tue, 03 Feb 2026 21:05:22 GMT

Hey,

I'm using FXTH8711 with RTI to 32ms and PWU wake-up mode to 1 second. These 2 timers use LFO clock (always ON in RUN/STOPx modes).

I have one specific processus for RTI and one other for PWU.

With the PWU: the TPMS wake-up and resets from reset-vector and when in my application I enable INTERRUPT (CLI) it enters in PWU handler. It is OK.

With the RTI the TPMS stays in STOP1 mode and when it resets (PWU timeout reached) the RTI interrupt flag is not set.

Is RTI timer running in STOP1 mode ? In the datasheet it is written that RTI timer can be used (with LFO clock) to wake-up from STOP1 because of interrupt event. It is indicated too that any reset (example: wake-up from STOP1 mode) clears the RTIF (RTI Flag pending event) so in my application I can never check if this timeout has been reached to execute a specific processus associated to RTI.

Can you help me please ?

Best regards,

Romain

Re: FXTH87 STOP1 RTI Error

TomasVaverka — Mon, 03 Sep 2018 10:12:15 GMT

Hi Romain,

Yes, the RTI can be used as wake-up source from STOP1.

Below is an example of initialization to use the RTI as wake up source from STOP4 or STOP1:

// First clear flag

SRTISC_RTIACK = SET;

// Select LFO as clock

SRTISC_RTICLKS = CLEAR;

SRTISC_RTIS = period; // where period takes one of the values specified in Table 24

// Enable interrupt // No effect for wake up from STOP1

SRTISC_RTIE = SET;

It is correct that upon wake up from STOP1 on RTI interrupt, there will be no associated flag in TPMS_INTERRUPT_FLAG or SIMSES register.

This fact can be used to determine if the wake up from STOP1 was due to RTI or not; for example the following can be done upon wake up from STOP1: if SPMSC2_PDF is set, TPMS_INTERRUPT_FLAG and SIMSES are clear and RTI interrupt was enabled before entering STOP1 (this information can be stored in a variable in the PARAM section) then the wake up was due to RTI and the specific process can be executed.

Best regards,

Tomas

Re: FXTH87 STOP1 RTI Error

mhusthutchinson — Mon, 03 Sep 2018 12:18:31 GMT

Hi Tomas,

Thanks for your help.

Best regards,

Romain