stop mode

[ben2]

Posted on October 26, 2005 at 05:24

stop mode

[ben2]

Posted on July 15, 2005 at 09:55

I am having problems entering stop mode, or more precisely on leaving stop mode.

I am trying the following:- code running from 4Mhz oscillator MCLK 48Mhz using PLL. switch clock source to 32 khz oscillator. stop PLL turn off external 4Mhz oscillator, (controlled via I/O pin). go into stop mode turn on external oscillator. enable PLL and wait for lock switch clock source to PLL. This does not work. The data sheet is not very clear on Stop mode. It appears that the CPU goes into stop. I can see the current consumption drop. I can get the CPU to come out of stop mode, the current consumption rises, however the program does not run. It appears the core has locked up in some way. If I follow the above stop procedure, but DONT stop the 4Mhz oscillator every things works as it should. I can only assume that in STOP mode the clock gets switched back to using the external osciallator(not using CK_AF), but nowhere in the datasheet does it mention this. Can anyone help me out ? many thanks Ben.

[anis_ben_abdallah]

Posted on July 15, 2005 at 11:27

Hi Ben,

I confirm, you can't exit STOP mode while the external oscillator is stopped, in fact you have to reenable the external oscillator '' externaly'' before exiting the STOP mode. If this is not possible in your application, then you will have to use the LPWFI mode which have power consumption not so far from the STOP one. In fact in LPWFI you can wake up the MCU while the external oscillator is stopped. Ciao Programmer 😉

[ben2]

Posted on July 15, 2005 at 13:58

Ok thank you.

Perhaps the Data sheet could be updated to make this a little clearer

[hichem2]

Posted on July 19, 2005 at 11:17

Hi all,

Yes you are right and the following note will be added in the next reference manual version: The external oscillator must be present in order to exit from STOP mode. With best regards, Hich 😉