Reset POR signal 5s in i.MX6

[janexu]

Hi,

We found that the display will no output sometimes when power on. and even if power off and then power on. the display is same. but if we press reset button 5s and provide POR 5s input. the display will back to normal.

We can accept if the display can back to normal with some method. our question is why it can be recovered by press reset button 5s, the reset button connect i.MX6 POR pad and also PMIC reset output.

Best Regards,

Jane Xu

[janexu]

Hi igor,

I don't find long crystal start-up time in i.mx6 datasheet. Can you tell me where I can find it?  We need press at least 5s to solve this issue.

Best Regards,

Jane Xu

[igorpadykov]

Hi Jane

crystal start-up time is defined in crystal datasheet, not i.MX6.

Best regards
igor

[janexu]

Hi igor,

I study the documents about crystal and oscillator, normally kHz crystal start up time is about 200 ~ 400 ms. Does this start up time special for i.MX6?

And another question is when reset signal is pull low by press the reset button, the i.MX6 PLL still work? My understanding is PLL will work after we release the reset button, am I right?

Best Regards,

Jane Xu

[igorpadykov]

Hi Jane

you can analyze timings adding gpio toggling in source codes

and observe it with oscilloscope.

>when reset signal is pull low by press the reset button, the i.MX6 PLL still work?

no.

>My understanding is PLL will work after we release the reset button, am I right?

right.

Best regards
igor

[igorpadykov]

Hi Jane

reason may be long crystals (24MHz, 32.768KHZ) start-up times, other

reason (after power off and then power on) is that board capacitors were

not fully discharged before power on, that is processor starts up having some

residual voltages. According to power up sequence it should start up from zero

voltages on all its pins (except VDD_SNVS_IN, USB_OTG/_H1_VBUS) .

Best regards
igor
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