Cold Start Reset duration

[Vu TRAN]

Posted on February 02, 2011 at 23:58

Cold Start Reset duration

[luca239955_stm1_st]

Posted on May 17, 2011 at 15:11

Hi,

if you are using a startup file that does initialize the RAM you could probably save time by skipping this step (if that's acceptable for your application).

[Vu TRAN]

Posted on May 17, 2011 at 15:11

Hi Luca,

Many thank for your quick reaction. Great idea, I try it but the gain is only about 150us (I am using IAR EW 120). As you can see in the attached file, the internal Reset\ signal goes High only after 2500us. I used MSP430 & ATTINY device where the cold start delay may be set to only 10us or 50 us... I don't know if there is a possibility to set up the device with the option register (or any thing else) to accelerate the start up time ?

Kind regards & thanks in advance for thoughts

[brazov22]

Posted on May 17, 2011 at 15:11

Hi,

you can try to trimmer the value of resistor and capacitor you have on the board for the reset pin, but I doubt you can go less the 80 us. brazov

[Vu TRAN]

Posted on May 17, 2011 at 15:11Hi Brazov

Good idea, but the reset pin is actually left open, Nothing connected to it. It will try to disable the internal BOR, just to see what happens.

Thanks.

[Vu TRAN]

Posted on May 17, 2011 at 15:11

Hi brazov,

I use STVP utility to disable BOR in  Option register but nothing changed ! in the reference manual RM0031 rev 6, you can read at paragraph 8.3.1 that '' the POR is held for a specified time '' but I never found the name of this parameter neither its spec. It will be great if you know it.

Regards

[brazov22]

Posted on May 17, 2011 at 15:11

Hi,

your idea can be good, but BOR can be disabled only by option byte and at this time it's to late to save time for start-up. brazov

[brazov22]

Posted on May 17, 2011 at 15:11

Hi,

have a look on datasheet -> POR is power on reset and BOR brownout reset. At power-on, BOR is always active, and ensures proper operation starting from 1.8 V. After the 1.8 V BOR threshold is reached, the option byte loading process starts, either to confirm or modify default thresholds, or to disable BOR permanently (in which case, the VDD min value at power down is 1.65 V). At start-up there is no way to disable BOR, according what I read on datasheet :(

brazov

[Vu TRAN]

Posted on May 17, 2011 at 15:11

Hi Brazov,

The concerned Option byte is in EEPROM partition. You can set or clear the bit BOR_ON in a non volatile way. By the way do you have an example code to put the device in Halt mode with the lowest consumption ? I can not reach the 350nA mentionned in the datasheet. In fact In halt mode with Flash memeory on I can only reach 2uA never lower even with all default peripheral OFF.

Regards.

[brazov22]

Posted on May 17, 2011 at 15:11

Hi,

you have to disconnect all from the board except the micro and use an amperometer able to measure current in the order of pico ampere. Also don't forget to put regulator in ULP mode.

PWR_UltraLowPowerCmd(Enable);

PWR_PVDCmd(Disable);

brazov