Raspberry Pi Output Test 101

#!/usr/bin/python
''' rp_output_test101.py

use the Raspberry Pi computer to exercise an LED (light emitting diode)
turn on and off, blink and dim via Pulse Width Modulation

the black terminal strip is located on the upper side of the Raspberry B+ board
there a two rows of 20 physical pins each
the upper row starts with the even pins 2 (upper left corner, ulc) to 40
the lower row starts with the odd pins 1 (lower left corner, llc) to 39

We will be using the following pins:
GND (pin 9)
GPIO_17 (pin 11)
Connect the LED (cathode, flat spot, shorter lead toward GND) in series with
a 200 to 500 ohm current limiting resistor between GPIO_17 and GND

Note: each GPIO is limited to no more than 15mA current draw
the sum of all GPIO current draws is limited to 50mA

to execute this code run IDLE as a super user via terminal command
sudo idle

or from the terminal (needs shebang line)
assume that the code is in directory rpi_python ...
cd rpi_python
sudo python rp_output_test101.py

for parts used see ...
http://www.canakit.com/raspberry-pi-starter-ultimate-kit.html

To run from the LXTerminal -->
cd rpi_python
sudo python rp_output_test101.py

code stored at

'''

import RPi.GPIO as gpio
import time
from datetime import datetime as dt


def output_17_on():
    # GPIO_17 will go to about +3.3 volt
    # you can use gpio.HIGH, True, or 1
    gpio.output(17, gpio.HIGH)

def output_17_off():
    # GPIO_17 goes to 0 volt
    # you can use gpio.LOW, False, or 0
    gpio.output(17, gpio.LOW)

def output_17_blink(blinks, delay=1):
    for n in range(blinks):
        print("Blink {}".format(n+1))
        output_17_on()
        time.sleep(delay)
        output_17_off()
        time.sleep(delay)

# use Broadcom GPIO 00..nn numbers (recommended)
gpio.setmode(gpio.BCM)

# set GPIO_17 as an output
gpio.setup(17, gpio.OUT)

# let's do some blinking
blinks = 5
delay = 0.5
print("LED blinking {} times with {} second delay".format(blinks, delay))
output_17_blink(blinks, delay)

print("LED on for 5 seconds ...")
output_17_on()
# keep LED on for 5 seconds
time.sleep(5)
output_17_off()
# wait 1 second
time.sleep(1)

print("Use pulse width modulation to dim the LED ...")
# faster than the eye can detect
frequency = 60
# you can change it with
# pwm.ChangeFrequency(frequency)

pwm = gpio.PWM(17, frequency)

# the LED is off at a dutycycle of 0 and fully on at 100
dutycycle = 0
pwm.start(dutycycle)
for dutycycle in range(0, 101, 10):
    print("dutycycle = {}".format(dutycycle))
    pwm.ChangeDutyCycle(dutycycle)
    time.sleep(2.5)

# also turns LED off
pwm.stop()

# reset all GPIO channels
gpio.cleanup()

#help(gpio)


#help(gpio)