Standby mode and alarm strange problem

sami · ‎2013-07-25

Posted on July 25, 2013 at 10:11

Hello

After producing the first 100 products for the customer , we noticed that 10% of the products around 10 units getting faults.

Our products wakeup from wakeup pin then after operation it goes to standby mode waiting again a wakeup button to be pressed , and also everyday at certian fix time it wakes up from the alarm of RTC . we noticed about 10 % of the units when wakes from RTC alarm the stm32f407 get stucks some where .. and cannot be closed waiting a reset only ...

the strange thing when waking up from wakeup pin all is ok ... and no problem .

we have been duging for a week.. is it bug of STM32f4 with RTC alarm and standby .. or what i am doing wrong here ..

Thank you in advanced

Nickname12657_O · ‎2013-07-25

Posted on July 25, 2013 at 22:49

Dear gentlemen,

Yes, we confirm the limitation. We recently ( 2 months ago ) added in our official errata

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/errata_sheet/DM00037591.pdfhttp://

Details in Section 2.1.5, We have a solution or let's say a workaround to modify the sequence of entry code to Standby mode to avoid that lockup situation. the entry logic is level sensitive and not edge, So if the external source is high, the RTC alarm will not be seen and also other sources, except reset.

Cheers,

STOne-32