SolutionsToNopLEDsAndNopNeoPixel < IoT_Course

Tags: view all tags

---+ Solutions to Exercise 2: LEDs
---++ Exercise 1:

Here is the screen dump of a REPL session switching the builtin LED on and off:

<img alt="builtinLED.png" height="152" src="%ATTACHURL%/builtinLED.png" title="builtinLED.png" width="576" />
---++ Exercise 2:

This is the most simple program in embedded systems. So... nothing much to say!

%ATTACHURL%/blink.py.txt
---++ Exercise 3:

Exercise 3 is not much more difficult neither. We create a function called <i>pulse, </i>which takes a !<i>pulseLength</i> as parameter. This function switches the LED on for pulseLength seconds and off again for another pulseLength seconds. This function is called 3 times with a short !<i>pulseLength,</i> 3 times with a long _pulseLength_ and again 3 times with a short _pulseLength_.

Here is the code:

%ATTACHURL%/sos.py.txt
---++ Exercise 4:

This was an exercise we did during the !IoT workshop at the African Internet Summit 2019 in Kampala, Uganda and the solution comes from this workshop.

It defines a function intensityCycle, which increases the PWM duty cycle in steps given by the _resolution_ parameter and keeps this intensity stable for a duration given by the duration parameter. It does so for duty cycle 0 up to duty cycle 1 and then back to duty cyle 0.

At the Kampala workshop we also had a demo program cycling the intensity not in a linear but a sinusoidal fashion. Both programs are given here:

%ATTACHURL%/pwmExerciseSol.py.txt : the linear cycle and

%ATTACHURL%/pwmLED.py.txt : the sinusoidal cycle
---++ Exercise 5:

Switching on the LEDs one by one we see that
   * address 0 corresponds to the middle LED
   * address 1 to the top LED
   * and the others in clockwise progressing around the circle
%ATTACHURL%/ws2812Addresses.py.txt
---++ Exercise 6 and 7:

Once we know the LED addresses it is easy to switch them on clockwise and anticlockwise

%ATTACHURL%/ws2812Colors.py.txt

%ATTACHURL%/ws2812ColorsCCW.py.txt

Changing the colors is done by passing the corresponding RGB (Red,Green,Blue) values to the WS2812 driver.

-- %USERSIG{UliRaich - 2020-05-06}%

---++ Comments

%COMMENT%

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
txt	blink.py.txt	r1	manage	0.6 K	2020-05-06 - 10:00	UliRaich
png	builtinLED.png	r1	manage	17.8 K	2020-05-06 - 09:47	UliRaich
txt	pwmExerciseSol.py.txt	r1	manage	1.3 K	2020-05-30 - 15:05	UliRaich
txt	pwmLED.py.txt	r1	manage	1.0 K	2020-05-30 - 15:05	UliRaich
txt	sos.py.txt	r1	manage	0.9 K	2020-05-30 - 15:05	UliRaich
txt	ws2812Addresses.py.txt	r1	manage	1.1 K	2020-05-30 - 15:05	UliRaich
txt	ws2812Colors.py.txt	r1	manage	1.3 K	2020-05-30 - 15:05	UliRaich
txt	ws2812ColorsCCW.py.txt	r1	manage	1.5 K	2020-05-30 - 15:05	UliRaich

Topic revision: r2 - 2020-05-30 - UliRaich