3.3V Output

[M11]

Hello,

Just a quick question: I need 3.3V output to use for a seperate small board to operate in combination with the CORE2-ROS. Is it recommended to use the PWM of pin 1 of the hServo port, and use 100% duty cycle?

Edit:
Or can I use the 3.3V output pin from the Raspberry Pi of the CORE2-ROS?

Regards,

Mike

[radeknh]

Hi,

if your external module need no more than 1mA and the total capacitance at the supply input is no higher than 470nF, you can supply it from the pin. You should keep in mind that there is also a series resistor. It is 330R on hSensor port pins, and 1k on hServo signal pins. With 330R and 1mA you will lose 0,33V, so the effective voltage will be between 2,8 and 3V.

The second idea is much better, the only challenge is that you have to solder wires there. But you can draw 50mA from there, or even 250mA for the newer versions of Raspberry.

[M11]

Hello,

Thanks for the reply. I will solder it to the Raspberry Pi then.

so the effective voltage will be between 2,8 and 3V.

This got my attention. For a different device (a motor controller for a stepper motor) we need to control the direction and the steps. The direction is straightforward. But the steps are not. The motor controller can take a PWM signal as pulses for the steps, it needs to be between 3.3V and 24V. I want to use the PWM signal from the hServo port for that, because all hMotor ports are being used already. I can try this on thursday, but maybe you could directly tell me if that will work. Powering the motor controller is being taken care of in a different manner.

Regards,

Mike

[radeknh]

I would give a 70% of chance that it will work. If not, you can add three additional transistors, like it is shown in the controller documentation.