GPIO limits

[Ivan219]

Hello, I have some questions with gpio mA limits. I read that every digital GPIO have 16 mA limit, aren't I? 3,3V have 50 mA, yes?
And can I connecting LED (with a resistance of course) only to digital gpio?

[joan]

The overall limit for the 3V3 rail is not specified (for the A+/B+/Pi2). The limit for individual gpios is still 16mA.

What else would you want to connect a LED to?

[mahjongg]

The combined total limit of all GPIO's is limited to 50mA. Each GPIO is limited to 15mA.

[Ivan219]

What else would you want to connect a LED to?

Else I want connect motor but it is designed for 5 volts... And speaker I think it can be connect via digital gpio too? Can I connect speaker directly (without anything)?

[Ivan219]

The combined total limit of all GPIO's is limited to 50mA. Each GPIO is limited to 15mA.

If every led consumption 10 mA I can connect only five leds, yes?

[drgeoff]

What else would you want to connect a LED to?

Else I want connect motor but it is designed for 5 volts... And speaker I think it can be connect via digital gpio too? Can I connect speaker directly (without anything)?

There are very few motors which can do anything useful when run from 3.3 volts and not allowed to consume more than 15 mA. And any motor with brushes is liable to produce sparks which if they don't damage the SoC are likely to disrupt it.

Most speakers are low impedance, usually between 4 and 32 ohms. 32 ohms and 3.3 volts gives 100 mA.

So a motor or speaker is not suitable for direct connection to a GPIO.

[Ivan219]

And can I connect motor (from toy-car) to 5 volts gpio?
The limit in the amount of 50 mA applies to all pins gpio or for digital only?
I also had in mind the speaker of the toy car, small in size.

[joan]

And can I connect motor (from toy-car) to 5 volts gpio?
The limit in the amount of 50 mA applies to all pins gpio or for digital only?

The Pi has no 5V gpios.

All Pi gpios are digital.

[Ivan219]

The second connector is not 5 volt? Can I connect motor to 5 volt and next to gpio?

[joan]

The second connector is not 5 volt? Can I connect motor to 5 volt and next to gpio?

It is 5V. It is NOT a gpio.

[jojopi]

If every led consumption 10 mA I can connect only five leds, yes?

That is a correct calculation. However, you should find that modern LEDs are acceptably bright on a lot less than 10mA.

For red, yellow, and green LEDs try starting with a 1kΩ series resistor. Blue and white drop more voltage, so try 470Ω. This should keep the current below 2mA each, and then you can use as many LEDs as there are GPIOs.

[Ivan219]

If every led consumption 10 mA I can connect only five leds, yes?

That is a correct calculation. However, you should find that modern LEDs are acceptably bright on a lot less than 10mA.

For red, yellow, and green LEDs try starting with a 1kΩ series resistor. Blue and white drop more voltage, so try 470Ω. This should keep the current below 2mA each, and then you can use as many LEDs as there are GPIOs.

Thank you for information!

[Ivan219]

It is 5V. It is NOT a gpio.

Ok, I realized. No ways connect 5volts-motor-gpio, yes?

[mahjongg]

no, you cannot connect -anything- between the 5V power pin, and a GPIO, as this -will- leak 5V to the GPIO, and the PI does not tolerate 5V (more than 3.3V) on its GPO pins, as this will cause permeant damage to your PI to the level that the PI will be totally destroyed!

The correct way to control devices needing more than 3V3 or more than 15mA, is to use the GPIO to switch on a transistor, the transistor can then switch a 5V (or 12V) signal.

There are many examples in this forum and in books and magazines, like the free magpi magazine, for you to learn from.

[Ivan219]

Ok, I understand you. And the last question - I can't connect 5v to ground (NO gpio), yes?

[DougieLawson]

Ok, I understand you. And the last question - I can't connect 5v to ground (NO gpio), yes?

If you connect 5V0 to GND you'll create a short circuit across your power supply. The RPi will instantly shutdown (due to lack of power) and the power supply and cable will start to get hot. Do it for long enough and you'll cause serious damage to everything.

[Ivan219]

Ok, I understand you. And the last question - I can't connect 5v to ground (NO gpio), yes?

If you connect 5V0 to GND you'll create a short circuit across your power supply. The RPi will instantly shutdown (due to lack of power) and the power supply and cable will start to get hot. Do it for long enough and you'll cause serious damage to everything.

Yes, I know. I mean connect 5v-motor-ground.

[DougieLawson]

If you do that you'll risk destroying your RPi with the back EMF when the motor stops. You'll risk corrupting your SDCard if the motor draws more current than available and starves your RPi.

Use an entirely separate supply for the motor.

[boyoh]

Ivan , I suggest you get a book on simple basic electronics
in your language, and do some basic circuit building
You will then have a better understanding of of what
you want to do, You will learn how to apply Ohms Law.
Start with a bread board and a power supply.