Minimum RESET pulse

piebat
Posts: 5
Joined: Mon Oct 26, 2015 8:32 pm

Minimum RESET pulse

Postby piebat » Fri Dec 11, 2015 2:08 am

To wake after a deepsleep and before it expire, I would like use a reset pulse generator like CAT871. This is necessary because I want wake up the ESP8266 when a free fall interupt is generated by an accelerometer and this interrupt is a latched signal and not a pulse.
Please coud you tel me what has to be the minimum negative pulse lenght?
I can select between 2.2 ms and 70ms.
Thenks and regards.

chaeplin
Posts: 4
Joined: Wed Dec 02, 2015 5:29 pm

Re: Minimum RESET pulse

Postby chaeplin » Mon Dec 14, 2015 12:47 am

I think a pulse is needed.
When reset pin is in low, esp is in reset state and clock is not running.
I have a dash like button using reset and deepsleep.
With following circuit, if switch is on, esp is in reset state and not running code. After releasing switch, esp start.

https://raw.githubusercontent.com/chaep ... /npntr.png

more:
external one shot reset using monostable flip flop ( http://www.bowdenshobbycircuits.info/page9.htm )
- pin 16 go LOW while running(digitalwrite to low) to prevent more reset.
https://raw.githubusercontent.com/chaep ... _schem.png


ref: viewtopic.php?f=7&t=259&p=1023&hilit=reset+pulse#p1023

piebat
Posts: 5
Joined: Mon Oct 26, 2015 8:32 pm

Re: Minimum RESET pulse

Postby piebat » Mon Dec 14, 2015 5:21 pm

Thanks for help. I need that the reset pulse is generated even if the line is kept low, because I need to verify from where came the reset, when the system wakeup. So I found the answer: "how long at least shoud be low the reset to achieve it?" at http://bbs.espressif.com/viewtopic.php?p=5027#p5027, it is 100us, and I think that the CAT871 IC could work fine if I use two line as manual reset.

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