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--- haas:fall2020:common:projects:led0 [2020/08/25 09:31] – [Input and Output via the GPIO pins on the pi] wedge
+++ haas:fall2020:common:projects:led0 [2020/09/18 09:28] (current) – [The Circuit to Construct] wedge
@@ Line 3: / Line 3: @@
 =====Objective=====
-To create a program that generates a unique pattern of lit LEDs on your pi based on constraints
+To successfully interface an LED to your pi and control it via software (commands, provided program)
-{{page>haas:fall2020:common:projects:abstract}}
+We also further utilize enforced time constraints, tying project credit to your starting on the project before the deadline (so be sure to plan accordingly!)
+=====Abstraction=====
+{{page>haas:fall2020:common:projects:abstraction&noheader}}
 =====Locational Awareness=====
 {{page>haas:fall2020:common:projects:location&noheader}}
 =====Reading=====
@@ Line 27: / Line 29: @@
 Please note the orientation of the pi (ethernet/USB at bottom) to calibrate yourself to the location of pin 1 and all subsequent pins, along with their identified function (ie top left pin, pin 1, provides a constant 3.3v DC power)
+We can also get a live update on the state of each pin on our pi itself, using the '**gpio readall**' command at our pi prompt:
 <cli>
-yourpi:~/src/c4eng/led0$ gpio readall
+yourpi:~/src/desig/led0$ gpio readall
  +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+
  | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
@@ Line 56: / Line 60: @@
  | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
  +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+
-yourpi:~/src/c4eng/led0$
+yourpi:~/src/desig/led0$
 </cli>
-=====Program=====
+Yes, it may be packed with information, but it is an informative, technical reference.
-It is your task to write a program to interface with an LED (light emitting diode), a nice software-hardware connection, on your raspberry pi.
-====On your pi====
+Why is this so layered and directed, you may ask? Well, it is a matter of competing standards (approaches to identification of each pin, based on particular reference points).
-Develop, test, and run this program on your pi. When done, submit it on lab46.
-To utilize the needed functionality for this project, you will need to ensure you have the following packages installed:
+For example, the "Physical" columns (dead center) in the center conform to the image diagram I posted above of the 40 pins (where pin 1 is the top-left).
-  * **build-essential** (hopefully you took care of this in ntr0)
+The "BCM" columns (far left and far right) refer to the hardware identifications for each pin by the manufacturer. You might notice that BCM pin 17 (physical pin 11) corresponds to wPi pin 0.
-  * **wiringpi**
-===Installing wiringpi===
+And the "wPi" columns (second from left, and second from right), correspond to the pin identifications as use by the wiringPi library, which we are using here.
-An exception to the usual package installation process, especially for those with a Raspberry Pi model 4B: when you install **wiringpi** the usual way, we may end up with errors when proceeding further, such as the following:
+Additionally, we see "Mode" and "V" columns; mode informs us of the operating mode of that pin at present configuration (IN means it is configured for INPUT, OUT means it is configured for OUTPUT). V implies voltage on the pin (0 means no voltage, 1 means there is voltage present at time of checking). For this project, we will be configuring a specific pin to OUTPUT mode, and modulating it between a state of ON (1) and OFF (0).
+So, in exploring the use of the table: if we wanted to hook a component up to wiringPi pin #0, that corresponds to manufacturer (BCM) pin 17, which is physical pin 11.
+You will want to verify placement before supplying power, that is why we are taking things slow, and providing you opportunities to confirm (by posting pictures in the discord channel) before proceeding.
+It may seem a bit bewildering or overwhelming at first, but like anything, time and exposure will ensure it becomes increasingly second nature.
+=====Wiring up our first circuit=====
+Here we are, about to embark on our first foray into mixing with hardware and software.
+In this project, we will be hooking up a peripheral to a couple of our Raspberry Pi pins: a light emitting diode (LED) and supporting hardware, and then proceed to interface with it to control its state (of being ON or OFF).
+You have likely encountered LEDs endlessly in your everyday life: commonly used as a "power light", which when lit, indicates the device is powered on, among many, MANY, **MANY** other applications.
+For this endeavour, you will need to obtain the following items out of the electronics kit you obtained for the class:
+====(1) breadboard====
+In your electronics kit, what will serve as the base, or mounting point for our electronic circuits, will be the solderless breadboard, which resembles the following:
+{{ :haas:fall2020:common:projects:breadboard.jpg |}}
+<WRAP round info>We will be inserting the metal legs of various components in various holes on the breadboard, to connect our circuit together.</WRAP>
+On the breadboard, there are 2 different pathways of connectivity. If you look along the top and bottom of the breadboard, do you see the red and blue strip running horizontal across the board? That means that ALL pins in that row are hooked together (all the pins along the blue line are hooked together with each other, all the pins along the red lines are hooked together with each other). We will be using that to to provide things like a common voltage (+) or a common ground (-) to components that need such things.
+In the middle of the breadboard, separated by the valley in the plastic molding, are columns of connected pins (unique columns, also separate from the other side of the valley). Each group of those 5 pins is hooked together.
+You'll notice occasional "by 5" counting off silkscreened on the breadboard, which can be used to try to keep things organized.
+Here's a logical diagram of the breadboard layout:
+{{ :haas:fall2020:common:projects:breadboardlogic.png?400 |}}
+Here's a good video overview of the functionality of a breadboard:
+  * https://www.youtube.com/watch?v=6WReFkfrUIk
+====(1) T-cobbler and data cable====
+In your kit should be a T-shaped device (known as the "T-cobbler" with some aspect of pin names silkscreened on it, and a 40-pin ribbon cable). Colors may vary, but essentially it looks like this:
+{{ :haas:fall2020:common:projects:tcobbler.jpg?400 |}}
+<WRAP info>Note that the T-cobbler, on top has a set of pins, enclosed in a plastic rectangle, shaped to fit the ribbon cable.</WRAP>
+<WRAP info>The plastic rectangle should have a notch cut out from it, and notice that the ribbon cable connector has a notch included in it. That is a key to indicate how you need to connect the ribbon cable into the T-cobbler</WRAP>
+====(1) red LED====
+You have a few LEDs included in your kit, some of notably different colours. Go for one of the distinctly red looking ones, resembling the following:
+{{ :haas:fall2020:common:projects:redled.png?400 |}}
+Do note that the two legs of the LED are not equal in length.
+The longer leg is the positive side of the LED, called the “anode,” and the shorter leg is the negative side, called the “cathode.” Within an LED, current can only flow from the anode (positive side) to the cathode (negative side) and never in the opposite direction.
+====(1) 220 Ohm resistor====
+Your kit should come with 3-4 packs of differently rated resistors (220, 1K, and 10K). You want ONE of the lowest rated ones, the 220 ohm variety. You should see the value marked on the paper strip holding the legs of the resistors.
+{{ :haas:fall2020:common:projects:220ohm_resistor.jpg?400 |}}
+<WRAP round info>The color bands are important, not the body color itself. You resistor body may be beige, may be blue, but the color of the 4-5 rings is what is important. Here we have red (2), red (2), brown (x10); 22 * 10 = 220</WRAP>
+<WRAP round info>Unlike the LED, where the direction of connection matters, it does not matter which way you plug in a resistor. Its purpose is simply to resist.</WRAP>
+====male to male jumper wire, as needed====
+As a final piece of equipment you will need, locate and have a few male-to-male jumper wires handy for use in our circuit:
+{{ :haas:fall2020:common:projects:male_male_jumper.jpg?400 |}}
+=====The Circuit to Construct=====
+With those components, you will want to place them onto your breadboard in a manner similar to this:
+{{ :haas:fall2020:common:projects:led_circuit.png?400 |}}
+Take note of how everything is being plugged in, and what connection on the T-cobbler is being utilized.
+Notice how the circuit runs from ground to LED to resistor to pin "GPIO17/Physical pin 11/Wiring Pi pin 0"
+Before you seek to actually test your circuit, please get verification to proceed from the class channel on discord by posting a clear picture of everything. There are MANY moving parts, and especially as we have our first exposure, it is best to insert as many quality control checks as possible to ensure the greatest chances of mistakes are mitigated.
+====Testing connectivity====
+To verify whether everything is hooked up correctly (including the correct positioning of the LED), please try the following:
+===Set wiringPi pin 0 to OUTPUT mode===
+Remember in that big readout of all the gpio pins above? Take a look at the settings for wiringPi pin 0:
 <cli>
-yourpi:~/src/c4eng/led0$ gpio readall
+ +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+
-Oops - unable to determine board type... model: 17
+ | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
+ +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
+ | ...
+ |  17 |   0 | GPIO. 0 |   IN | 0 | 11 |
 </cli>
-What you will need to do is manually install an updated (and out of database) version of the **wiringpi** package, as follows (looking out for errors along the way):
+Note that, currently wPi pin 0 is set to INPUT (with no voltage). We need to change that to OUTPUT, which you can do by doing the following:
 <cli>
-yourpi:~/src/c4eng/led0$ wget https://project-downloads.drogon.net/wiringpi-latest.deb
+yourpi:~/src/desig/led0$ gpio mode 0 OUT
-...
-yourpi:~/src/c4eng/led0$ sudo dpkg -i wiringpi-latest.deb
-...
-yourpi:~/src/c4eng/led0$ rm -f wiringpi-latest.deb
 </cli>
-===The program (led0.c)===
+At which point that particular pin will be changed from IN to OUT:
-The program you will need is once again provided via a grabit on lab46, source code also included here for study:
-<code c>
+<cli>
-#include <stdio.h>     // include support for C standard library input/output functionality
+ +-----+-----+---------+------+---+---Pi 4B--+---+------+---------+-----+-----+
-#include <stdlib.h>    // include support for general C standard library functionality
+ | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
-#include <wiringPi.h>  // include support for wiringPi library functionality
+ +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
+ | ...
+ |  17 |   0 | GPIO. 0 |  OUT | 0 | 11 |
+</cli>
-int main (void)        // every program has a starting point, for us in C, it is main()
+Okay, output mode enabled, now to twiddle the bits off and on:
-{
-    //////////////////////////////////////////////////////////////////////////
-    //
-    // Declare variables
-    //
-    int gpio_pin  = 17;   // set to GPIO pin we are hooking LED circuit into
-    //////////////////////////////////////////////////////////////////////////
+<cli>
-    //
+yourpi:~/src/desig/led0$ gpio write 0 1      ## activate voltage on wiringpi pin 0 (turn on)
-    // Initialize wiringPi subsystem and verify no errors occurred
+yourpi:~/src/desig/led0$ gpio write 0 0      ## deactivate voltage on wiringpi pin 0 (turn off)
-    //
+</cli>
-    if (wiringPiSetup() == -1)
-    {
-        fprintf (stderr, "[error] wiringPi initialization has failed!\n");
-        exit (1);
-    }
-    //////////////////////////////////////////////////////////////////////////
+If your LED is hooked up correctly, the LED should light up, ideally during the ON line.
-    //
-    // Display usage information to the user
-    //
-    fprintf (stdout, "Starting program, interrupt to terminate (CTRL-c)\n");
-    //////////////////////////////////////////////////////////////////////////
+If you get no activity out of the LED, try reversing it and try again.
-    //
-    // Initialize utilized GPIO pin to OUTPUT mode
-    //
-    pinMode (gpio_pin, OUTPUT);
-    //////////////////////////////////////////////////////////////////////////
+=====Program=====
-    //
+It is your task to compile, run, and understand a program to interface with an LED (light emitting diode), a nice software-hardware connection, on your raspberry pi.
-    // Repeat until interrupted (CTRL-c to interrupt)
-    //
-    while (1)
-    {
-        digitalWrite (gpio_pin, LOW);   // set signal on gpio_pin LOW
-        delay (1000);                   // delay for 1000ms
-        digitalWrite (gpio_pin, HIGH);  // set signal on gpio_pin HIGH
-        delay (1000);                   // delay for 1000ms
-    }
-    return (0);
-}
-</code>
-The program for this project is complete. You merely have to get it on your pi, compile it, and run it, with the appropriate circuitry hooked up to the specified places. In future projects you will start implementing more logic to attain further functionality.
+The program files provided for this project are complete. You merely have to get it on your pi, compile it, and run it, with the appropriate circuitry hooked up to the specified places. You will want to make sure you UNDERSTAND what is going on.
-=====Specifications=====
-Your program should:
-  * have valid, descriptive variable names of length //no shorter than// 4 symbols
+In future projects you will start implementing more logic to attain further functionality.
-  * have consistent, well-defined indentation (no less than 4 spaces per level of indentation)
-    * all code within the same scope aligned to its indentation level
-  * have proximal comments explaining your rationale and what is going on, throughout your code
-  * perform the intended operation, outputting the correct/accurate information in indicated format
-  * at the end of your main() function, use a single return statement to conclude your code, return a 0 indicating successful operation
-=====Grabbing project resources=====
+====Grabbing project resources (on lab46)====
 I have prepared a **grabit** for resources related to this project. To obtain:
@@ Line 167: / Line 213: @@
 At which point you can change into the newly created and populated **led0** directory.
-=====Compiling=====
+====Getting project resources from lab46 to your pi====
-Since the grabit brought in a Makefile, you can compile your code simply by typing: **make**
+Okay, you've snagged the project files on lab46. Now, how to get them to your pi?
-Any compiler errors will go into a text file called **errors**
+The same way you've been juggling project files already, by using your mercurial repository!
-To do a full cleaning, run: **make clean** then **make** (or **make debug**)
+Using the **hg** tool, be sure to **add**, **commit**, and **push** successfully on lab46.
-If you'd like to see compiler messages as you compile, run: **make debug**
+Then, over on your pi, use **hg** to **pull** and **update** the new changes into place. Then you can proceed.
-When done and ready to submit, on lab46: **make submit**
+====On your pi====
+Study and run this program on your pi in conjunction with testing and verifying operation of your properly hooked up electronics circuit. When done, submit it on lab46.
-=====Layout=====
+To utilize the needed functionality for this project, you will need to ensure you have the following packages installed:
-This is the first project to dig into our electronics kit. You have been given a few weeks to get your pi up and running.
-You will need the following items from your electronics kit:
+  * **build-essential** (hopefully you took care of this in ntr0)
+  * **wiringpi**
-====(1) breadboard====
+===Installing wiringpi===
+An exception to the usual package installation process, especially for those with a Raspberry Pi model 4B: when you install **wiringpi** the usual way, we may end up with errors when proceeding further, such as the following:
-====(1) T-cobbler====
+<cli>
+yourpi:~/src/desig/led0$ gpio readall
+Oops - unable to determine board type... model: 17
+</cli>
-====(1) red LED====
+What you will need to do is manually install an updated (and out of database) version of the **wiringpi** package, as follows (looking out for errors along the way):
-====(1) 220 Ohm resistor====
+<cli>
+yourpi:~/src/desig/led0$ wget https://project-downloads.drogon.net/wiringpi-latest.deb
+...
+yourpi:~/src/desig/led0$ sudo dpkg -i wiringpi-latest.deb
+...
+yourpi:~/src/desig/led0$ rm -f wiringpi-latest.deb
+</cli>
-====male to male connector wire, as needed====
+=====Compiling=====
+Since the grabit brought in a Makefile, you can compile your code simply by typing: **make**
+Any compiler errors will go into a text file called **errors**
+To do a full cleaning, run: **make clean** then **make** (or **make debug**)
+If you'd like to see compiler messages as you compile, run: **make debug**
+When done and ready to submit, on lab46: **make submit**
 =====Submission=====
@@ Line 204: / Line 270: @@
   * Track/version the source code in a repository
   * Submit a copy of your source code to me using the **submit** tool.
+  * Post required images and obtain needed confirmation to proceed from me on class channel on discord.
 To submit this program to me using the **submit** tool, run the following command at your lab46 prompt:
@@ Line 221: / Line 288: @@
 <code>
 :led0:final tally of results (26/26)
-*:led0:post picture of unpowered layout to #desig and get approval [4/4]
+*:led0:post picture of unpowered layout to #desig and get approval [6/6]
-*:led0:post picture to #desig by Sunday before deadline [2/2]
+*:led0:post picture to #desig by Sunday before deadline [4/4]
-*:led0:post picture of powered LED to #desig [4/4]
+*:led0:post picture of powered LED to #desig [6/6]
-*:led0:grabit the code on lab46 by Sunday before deadline [2/2]
+*:led0:grabit the code on lab46 by Sunday before deadline [4/4]
 *:led0:code is pushed to lab46 repository [6/6]
-*:led0:no negative compiler messages for program [6/6]
 </code>