Is brownout detection usable now?

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urbanze
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Re: Is brownout detection usable now?

Postby urbanze » Wed Aug 22, 2018 5:58 pm

What is the maximum value can I get to trigger BOD? In menuconfig, maximum is ~2.7V (7<<bit) == (10000000), but whats happen if write (11111111)? I would like to get ~3V, this is possible?

WiFive
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Re: Is brownout detection usable now?

Postby WiFive » Wed Aug 22, 2018 9:44 pm

It is a 3 bit value so 7 is max

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urbanze
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Re: Is brownout detection usable now?

Postby urbanze » Wed Aug 22, 2018 10:04 pm

WiFive wrote:It is a 3 bit value so 7 is max
Oh sorry, bodwait_reg is larger. My mistake. But if 7 is max, I should 3V is impossible... Thanks.


I testing my own isr to write some data in flash in case BOD trigger, but I think that nvs API is little slow. What API can I use to write in flash with velocity focus?

ESP_igrr
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Re: Is brownout detection usable now?

Postby ESP_igrr » Wed Aug 22, 2018 10:59 pm

When brownout is detected, it is very likely that reliable flash writes are already impossible (unless you have a 1.8V capable part). In fact, in many cases it is the flash chip that browns out first.

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urbanze
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Re: Is brownout detection usable now?

Postby urbanze » Wed Aug 22, 2018 11:03 pm

ESP_igrr wrote:When brownout is detected, it is very likely that reliable flash writes are already impossible (unless you have a 1.8V capable part). In fact, in many cases it is the flash chip that browns out first.
:( Can you say any "internal" method to write data to avoid lost data in ram?

ESP_igrr
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Re: Is brownout detection usable now?

Postby ESP_igrr » Wed Aug 22, 2018 11:05 pm

Possibly RTC memory via RTC_NOINIT_ATTR, but it may be lost if the supply voltage drops below about 1V.

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urbanze
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Re: Is brownout detection usable now?

Postby urbanze » Wed Aug 22, 2018 11:12 pm

ESP_igrr wrote:Possibly RTC memory via RTC_NOINIT_ATTR, but it may be lost if the supply voltage drops below about 1V.
Ya, this is my last ideia but with power off, all ram is lost. I will try tomorrow.

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urbanze
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Re: Is brownout detection usable now?

Postby urbanze » Thu Aug 23, 2018 12:35 pm

I testing velocity of BOD comparator but with ~2.7V +- 0.05V make little hard to find specific latency.

What's the latency of BOD since threshold AND isr? In some PIC's is ~500ns + 2 cycles + X cycles to handle isr... And in esp32?

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