Which Micro controller for a rechargeable project

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Darkstar_Traceur
 
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Which Micro controller for a rechargeable project

Post by Darkstar_Traceur »

Hi everyone, Im currently building a portable LED project using ardunio, and I would love some help on discovering which micro controllers can recharge lithium batteries.


One of the things that really interested me is the trinket has a "USB+ (power out)". If I understand this, This pin only outputs 5V if plugged into a USB. Therefore you can attach a separate lithium charging circuit to this port and it will come alive and charge the battery only when the microprocessor is plugged in though the USB.
So far I know you can pair a Trinket with a charge backpack.
https://www.adafruit.com/products/2124

Seemingly even better the Lily Pad, seems to have a built in recharge circuit, but unfortunately wouldn't fit in my tube like designs, and it doesnt have a USB port
https://www.arduino.cc/en/Main/ArduinoB ... yPadSimple

So can anyone help me? Im definitely interested in becoming more informed?
Do other micro controllers have a "USB+ (power out)" pin like the trinket, allowing you to attach your own lithium charger?
Do any other micro controllers have a built in charge circuit?
Can it be done pragmatically? [if (USBPower==true) then digitalWrite(pin6, HIGH);]

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adafruit_support_mike
 
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Re: Which Micro controller for a rechargeable project

Post by adafruit_support_mike »

There are a total of three chips that will be involved.

The microcontroller handles the programmable logic, but can't regulate voltage or charge a LiPo.

The USB spec requires hubs to provide well-regulated 5v power, so boards with a USB connection usually connect a pin to the USB jack for 5v output. Boards that take power from other sources use a 5v regulator to reduce voltages higher than 5v to a smooth 5v rail.

The regulator can't charge a LiPo either though. The LiPo charging cycle is complicated, and batteries can be damaged or catch fire if they aren't charged properly. There are lots of dedicated chips to control a LiPo charging cycle though, so you just include one of those on the board if you want to charge the batteries.

Darkstar_Traceur
 
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Re: Which Micro controller for a rechargeable project

Post by Darkstar_Traceur »

Yes. I understand their are multiple chips involved.
However, im afraid dont feel like my question has been answered.

Im searching around to get and Idea of my alternatives are.
For example
1. There are some single units which have a USB hub, micro controler and lipo charger. (E.G. Arduino Fio https://www.sparkfun.com/products/10116 ... 1435709359)

2. Some boards have a USB+ (power out)" pin like the trinket, allowing you to attach your own lithium charger?

3. Can this USB+ port be created pragmatically on any board E.g. [if (USBPower==true) then digitalWrite(pin6, HIGH);]

These are my questions.
A) Are there any other pre-made boards like the Fio
B) Are there any other boards like the tinket that have the USB+ pin
C) Can the USB+ pin be simulated on any micro controller with a USB hub and how?

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adafruit_support_mike
 
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Re: Which Micro controller for a rechargeable project

Post by adafruit_support_mike »

Darkstar_Traceur wrote:1. There are some single units which have a USB hub, micro controler and lipo charger. (E.G. Arduino Fio https://www.sparkfun.com/products/10116 ... 1435709359)
The Fio isn't a USB hub. You can't even program it directly from a USB cable. You need an external USB-to-Serial adapter.

The Fio does have a LiPo charger on the board, and will charge a LiPo when the USB cable is connected.
Darkstar_Traceur wrote:2. Some boards have a USB+ (power out)" pin like the trinket, allowing you to attach your own lithium charger?
Yes, most development boards have some kind of pin connected to the main power rail, which will route power from the USB port when that's connected. You can connect a LiPo charger to that pin and charge a LiPo.
Darkstar_Traceur wrote:3. Can this USB+ port be created pragmatically on any board E.g. [if (USBPower==true) then digitalWrite(pin6, HIGH);]
No. A digital pin is limited to an output current of about 30mA. A LiPo charger will want between 100mA and 1000mA, depending on how it's configured.

If you're looking for a simple LiPo charger, we have the Pro Trinket LiPo Backpack which rides just above any of our Pro Trinket boards: https://www.adafruit.com/products/2124

Darkstar_Traceur
 
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Re: Which Micro controller for a rechargeable project

Post by Darkstar_Traceur »

Thank you so much :D

Im most interested with your answer to question 2
Yes, most development boards have some kind of pin connected to the main power rail, which will route power from the USB port when that's connected. You can connect a LiPo charger to that pin and charge a LiPo.
Is it possible that you could provide a list of common bords like the trinket that have this pin, for example I have never been able to identify it on the Arduino Uno, or Nano

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Franklin97355
 
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Re: Which Micro controller for a rechargeable project

Post by Franklin97355 »

I have never been able to identify it on the Arduino Uno, or Nano
That would be the 5V pin on those.

Darkstar_Traceur
 
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Re: Which Micro controller for a rechargeable project

Post by Darkstar_Traceur »

Im afraid I appear to have made an error or you may be incorrect.

As you can see in the following photo I have wired up a lipo battery to a Arduino Nano, and checked the 5V pin.
And while the Arduino only has a 3.7V source to draw upon (This battery is low) , it is still attempting to output thought the 5V pin.

This is not useful as it means the battery, will power the 5V pin, which will power the recharge circuit, which will attempt to recharge the battery.
Essentially the battery will attempt to recharge itself, which is a waste of the limited times a battery can be recharged.

Have I understood this correctly? Could you please tell me if its still possible, (A pin which only outputs when plugged in to a USB)?

Image


To summarise my understanding up until this point
Darkstar_Traceur wrote:
2. Some boards have a USB+ (power out)" pin like the trinket, allowing you to attach your own lithium charger?
Yes, most development boards have some kind of pin connected to the main power rail, which will route power from the USB port when that's connected. You can connect a LiPo charger to that pin and charge a LiPo.
Is it possible that you could provide a list of common bords like the trinket that have this pin, for example I have never been able to identify it on the Arduino Uno, or Nano
That would be the 5V pin on those.

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Franklin97355
 
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Re: Which Micro controller for a rechargeable project

Post by Franklin97355 »

You are correct, there is no pin connected only to the USB 5 volt input on the Nano and the Uno.

Darkstar_Traceur
 
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Re: Which Micro controller for a rechargeable project

Post by Darkstar_Traceur »

That is what this post is all about.
adafruit_support_mike wrote: Yes, most development boards have some kind of pin connected to the main power rail, which will route power from the USB port when that's connected. You can connect a LiPo charger to that pin and charge a LiPo.
Could you please provide me with a list of boards that do?
(For example the Trinket, etc...)

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Franklin97355
 
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Re: Which Micro controller for a rechargeable project

Post by Franklin97355 »

There is no list that I know of. You would have to check the schematics to be sure.

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