Emdad
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Raspberry pi 3b+ pmic

Sun May 05, 2019 12:36 pm

I shorts my rpi 3b+ pmic..i want to replace it with arduino board. can i do it??so i need some information that how to managed the power for rpi all sections. What's the logic to manage the power??

LTolledo
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Re: Raspberry pi 3b+ pmic

Sun May 05, 2019 1:23 pm

... to "attemp repair" your damaged RPi3B+ due to shorting 3.3v to 5v rail?

better buy a brand new RPi3B+ ($35) than spend more money and countless hair-pulling-frustrating hours on something that may not work.
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

Will5455
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Re: Raspberry pi 3b+ pmic

Sun May 05, 2019 1:23 pm

Emdad wrote:
Sun May 05, 2019 12:36 pm
I shorts my rpi 3b+ pmic..i want to replace it with arduino board. can i do it??so i need some information that how to managed the power for rpi all sections. What's the logic to manage the power??
no I do not think so. certainly not without A few diodes.
I do strange things and am sometimes the techhead stereotype.
deal with it!

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mahjongg
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Re: Raspberry pi 3b+ pmic

Sun May 05, 2019 1:40 pm

If you power both an RPI and an Arduino, and want to combine them, power both RPI and Arduino separately, and only connect GND (grounds) together.

if you connect a (5V) Arduino to a RPI GPIO pin, you MUST divide the 5V signal with a resistor divider to 3V, as putting 5V on a GPIO pin will instantly destroy your RPI )cause a latch-up in the SOC chip.

If you have damaged the voltage regulator of your PI by making a connection between its 3V3 and 5V signal, you can throw away your RPI, and buy a new one, RPI's PMIC voltage regulator cannot handle that, and is destroyed.

An RPI is NOT a drop in replacement for an Arduino.
and the "the logic to manage the power??" probably exists only in your imagination.
do you care to explain what you mean by "logic to manage the power" ? what is there to manage? :roll: :)

LTolledo
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Re: Raspberry pi 3b+ pmic

Sun May 05, 2019 2:13 pm

As I understood it, the OP want to use a $15 self-custom-programmed 5v-powered arduino as a replacement for the damaged PMIC on his $35 RPi3B+
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

hippy
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Re: Raspberry pi 3b+ pmic

Sun May 05, 2019 2:30 pm

LTolledo wrote:
Sun May 05, 2019 2:13 pm
As I understood it, the OP want to use a $15 self-custom-programmed 5v-powered arduino as a replacement for the damaged PMIC on his $35 RPi3B+
It's an interesting option, and should work. It won't be simple though.

The logic however should be; power-up the supplies, one at a time, highest voltage first.

If one had four bench supplies, one could probably do it with an Arduino switching relays. That's all the PMIC is in essence. Though a lot more than that in reality.

One probably won't be able to interface with the proprietary code in the binary blob on the Pi so the end result may not be ideal. I believe the Pi communicates with the PMIC, receiving status back, and setting the various voltage levels depending on loading and how it's configuring the SoC. Until the PMIC bricks itself that is.

It would be easier just to ask the Foundation to sell a replacement MxL704-R3 or failing that buy an MxL7704-AQB which would do all one would be trying to achieve with an Arduino.

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