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Can a GPIO drive a 20mA led?
Since the device will be running off battery, keeping the power use low (Zero maybe) while the LED is off as a priority. The GPIO supplies 3.3V when turned on and 0.0V votes when turned off. It also has a limit of a maximum of 4mA. The LED has a forward current of 20mA and a desired forward voltage of 2.0V.
How to choose the right resistor for GPIO?
To choose the right resistor (R1 and R? in the schematic) you will need to know: The voltage of the GPIO pins (normally 5V for Arduino and 3.3V for Raspberry Pi) The forward voltage drop of the LED (1.8V – 3.3V for low powered ones) The current of the LED (around 20mA for a low power one)
How is the led current set in a GPIO?
Select a FET with a threshold voltage about 1V below your supply voltage to ensure that it will be well into saturation when turned on, and then the voltage drop across the MOSFET will be low. (MOSFETs make very good switches.) The LED current will be set by ILED = (VCC – Vf – Vds)/R.
Is there a limit to the 4MA Max GPIO?
It also has a limit of a maximum of 4mA. The LED has a forward current of 20mA and a desired forward voltage of 2.0V. When the LED is turned on it will most likely be blinking (using PWM) in the low kilohertz range. After poking around I believe this may be the type of circuit I need.
Can you connect a GPIO pin to an led?
Connecting an LED to a GPIO pin can be done and is frequently done. But this will only work if the LED has a forward voltage drop of less than 5V (or 3.3V with some GPIO (some even as low as 1.1V!)).
What is the forward voltage of a GPIO led?
The GPIO supplies 3.3V when turned on and 0.0V votes when turned off. It also has a limit of a maximum of 4mA. The LED has a forward current of 20mA and a desired forward voltage of 2.0V. When the LED is turned on it will most likely be blinking (using PWM) in the low kilohertz range.