Simple LED Circuits explains calculating resistance for single LEDs as well as in series and parallel.
Powering LEDs on Breadboard
Most of the information I saw about testing LEDs with a breadboard using 220Ohm or 330Ohm resistors. I had some 2.2k resistors, so that is what I tried, and it works. Any generic LED can be used, you can use a resistance calculator to confirm what you need.
- GND to LED cathode (shorter leg)
- LED anode (longer leg) to 2.2k resistor
- Resistor to PA6
#!/usr/bin/python from pyA20.gpio import gpio from pyA20.gpio import port import time LED = port.PA6 gpio.init() gpio.setcfg(LED, gpio.OUTPUT) print("LED on.") gpio.output(LED,gpio.HIGH) time.sleep(1) print("LED off.") gpio.output(LED,gpio.LOW)
For multiple LEDs, try this and this.
Alternating LEDs with transistor
Switching between a green and red LED by turning the GPIO high or low. [Source]
Experimenting with having an LED fade in and out using pulse width modulation. [Source]
from pyA20.gpio import gpio from pyA20.gpio import port from orangepwm import * from time import sleep LED = port.PA6 gpio.init() pwm = OrangePwm(100, LED) val = 100 pwm.start(val) while True: for i in range(0,100): val-=5 pwm.changeDutyCycle(val) print(val) sleep(0.1) if not val: break for i in range(0,100): val +=5 pwm.changeDutyCycle(val) print(val) sleep(0.1) if val == 100: break pwm.stop()
I got some more blinkies, including a pair of RGB cathode LEDs. These LEDs have 4 pins. I actually had to test these to figure out the pin order, which is Red, GND, Green, Blue. You can blend colors. It looks like a microcontroller is the way to go for anything more complex than a basic circuit.