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Why is the reset pin driven high instead of left floating when unasserted? #474

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GMMan opened this issue Dec 18, 2019 · 5 comments · Fixed by #479
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Why is the reset pin driven high instead of left floating when unasserted? #474

GMMan opened this issue Dec 18, 2019 · 5 comments · Fixed by #479

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@GMMan
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GMMan commented Dec 18, 2019

I recently flashed esp-link to a D1 Mini clone and wired it into a consumer product that has an AllWinner R16 SoC and AXP233 PMIC. Everything worked fine out of the box except I had to issue a uC reset to get the SoC to actually enter FEL mode after setting it up to do so. I found that esp-link driving the RESET/PWROK line high was interfering with the SoC's watchdog reset. I changed all instances where esp-link drives the reset pin high to disabling output so it floats, and now the SoC is entering FEL mode as expected.

My question is why has esp-link been designed to drive reset high while idle? If a uC requires a specific powerup sequence, this would interfere with that. If the uC doesn't require a powerup sequence, the reset pin would have been pulled high on the board the uC is attached to anyway.

@tve
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tve commented Dec 20, 2019

Makes sense, didn't think of it and it never came up as a problem...

@uzi18
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uzi18 commented Dec 24, 2019

@GMMan @tve can look at it, should be possible to fix

Do you want to test bins? what flash files you usually use for module?

@GMMan
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GMMan commented Dec 24, 2019

This is what I'm using currently: https://github.com/GMMan/esp-link/tree/v3.0.14-floating-reset

My module is 4MB:512/512.

@uzi18
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uzi18 commented Dec 24, 2019

that's exactly what I wanted to do :) (change reset pin to input when not used)
so if it works for you please create PR

@GMMan
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GMMan commented Dec 25, 2019

Should I rebase it on the master branch?

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3 participants