Tag: programming

Raspberry Pi Project Progress— LCD Screen PT 3

Posted on by Kristina

To catch you up on parts one and two: setting up the LCD screen I had with a pin adapter (to use only 4 instead of 16) was trickier than anticipated. Most of the code I was using had been with the 16 pins in mind and not my particular setup with the extension board. So, I was stuck for a few days with one “dead end” of an error code.

After a much needed break, I processed all that I had learned, read, and tested during my previous attempts. This morning I didn’t intend to mess around with the Raspberry Pi, but after taking a few classes on Team Treehouse, I felt inspired to give it another go.

With a fresh mind, I decided to go back to the original source I was following for my particular kit and setup. The reason why I hadn’t used this code in the first place was because it was for a more complicated program than what I was trying to setup. But then I went back to the instructions and tried to setup the more complicated program. Although that still didn’t run, it did help me create a must-needed file for my setup.

Then, after trial and error of various forms of code, I noticed that the LCD screen began to blink. The blinking matched up to the code of five seconds. Finally, I had received some sign that the communication between the components was working. But, the screen was too bright and there was no text. Then, I remembered from all of my reading the previous days from various sources and forum responses that the nob on the back of the LCD screen needs to be adjusted sometimes. So, I adjusted it, and black text boxes appeared. One step closer!

Finally, I looked at the code for the more complicated program and started deleting the stuff that I didn’t think I needed. After more trial and error of deleting, altering, and re-entering code, the LCD screen finally lit up with the famous words: Hello World!

But it wasn’t perfect. There were some strings of code running across the screen that shouldn’t have been there. After I finally isolated the code that ended up working and saving a new file, I tested it again to see if the fix was complete. After a couple of more trial and errors, unpinning and re-pinning the wires…it finally worked!

Here were the main issues:

  • This setup required a code specifically for the GPIO extension board and ic2 connection. Out of all the sources I had researched online, none had the exact address specifications that this required except for the example code in the ultimate beginner kit tutorial book.
  • This here was the key factor in getting the code to run:

PCF8574_address = 0x27  # I2C address of the PCF8574 chip.
PCF8574A_address = 0x3F  # I2C address of the PCF8574A chip.
# Create PCF8574 GPIO adapter.
try:
mcp = PCF8574_GPIO(PCF8574_address)
except:
try:
mcp = PCF8574_GPIO(PCF8574A_address)
except:
print (‘I2C Address Error !’)
exit(1)

  • I had also created another file titled PCF8574.py with code from GitHub by Freenove.
  • Another step that was important were these imports:

from PCF8574 import PCF8574_GPIO
from Adafruit_LCD1602 import Adafruit_CharLCD

Admittedly, my best friend was FaceTiming me as I was doing this, and when the code ran the second time across the LCD screen I was so happy to share that moment with someone. I screamed in excitement and showed my friend the words across the screen, and she called over her daughter to see as well.

Small backstory: My best friend’s daughter is incredibly smart, and a Minecraft Master, so I’ve been trying to pass on the coding bug to her through Minecraft. I sent her the whole code of Minecraft and told her to just read it and see if it made any sense. When she came over to the screen to see the Raspberry Pi, I showed her the code and explained what the experiment was and how it worked.

But we all know that seeing is believing. So I told Sammy that I would make the screen say her name. A couple of clicks later, the screen displayed “Hello Sammy!” and I showed it to her. She was elated with a big smile, as if I had performed a magic trick!

What a rewarding moment. I had imagined what the moment would be like when I got this to work, I had even accepted the fact that it may not work, and that I would have to try a different route completely, but I never expected it all to have unfolded in such a beautiful way.

I think what made this time different than the previous was that I wasn’t going by too many forums or outside advice. I just used the one code from the direct source, all I had learned from, and tried to get it to work from there the way I wanted. And it did!

Through this project I realized my pattern for learning will be exactly this: study through online sources like Team Treehouse and Udemy, and then take “breaks” with Raspberry Pi projects. The back and forth of the two helps me not rush through the online programs too fast. I don’t want to just pretend like I’ve learned this, I want to really learn this, and therefore I want to pace it in a way that truly allows my brain to digest all of the new information.

I ended the fun project by sharing the news with my friend and the forum I had gone to help for in the previous attempt. I’ve never really been an active forum member before, but I see now how some online communities can be really comforting and helpful!

Now, onto the next project!

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Errno 121 – The Error Code that Haunts Me

Posted on by Kristina

This is an update from my previous post about the live update project with the Raspberry Pi and LCD screen. Since that post, I’ve spent hours free-falling down the rabbit hole of troubleshooting.

Here’s what happened. Turns out the LCD screen I have has an adapter already soldered onto it (which most instructional websites have the type that requires you to solder yourself) and only requires four pins / wires instead of the usual sixteen. That may sound as if this would be easier since soldering comes with risks for those who are new at it, but alas, it is not!

Finally, I was getting close. I hooked up the Raspberry Pi to a monitor and began inputting the code. Like I said, I’m new at this, so although I was able to follow the steps (and at this point, memorize half of them) I still need to do some digging later on to understand why I was following those steps.

I enabled the i2c using the raspi-config, installed smbus and the i2c python library, tested and re-tested the hardware with sudo i2cdetect -y 1 and did a bunch of updates and reboots, amongst other steps.

Little by little, some steps that hadn’t worked previously were . actually working, which showed some promise. However, no matter the steps taken and those that passed onto the next step, I was continuously met with the same exact error code:

Eventually, I had to use some lifelines. I asked a friend. Okay, I asked many friends because one was a real human who I actually know (who I am eternally grateful for!), and the other was the internet (aka Reddit). Although it wasn’t my original goal to set up remote capabilities as part of this project, it was a positive outcome that was necessary regardless! My friend had remotely logged into my Raspberry Pi to see if he could figure out the issue. Alas, the night ended with everyone stumped, and we decided to take a break and re-group.

Intuitively, I think that the issue is something small I am missing, perhaps something with the way the site-package files are being read on my Raspberry Pi, that I’m unable to see. Or, something with the “__init__” part, but I’ll need to do some more reading on this particular type of error message. Or, perhaps I need to edit some lines in that file path? Hmm.

Even though I have not yet had the “payoff” of seeing the text display onto the LCD screen, I have already learned so much through troubleshooting this project.

Most importantly, I take this as an important test and “rite of passage” for my journey into the programming world; error messages will happen, so I better get used to it (and love the process of fixing them) if I want to succeed and continue to grow in this field.

After years of undergraduate, graduate school, and working full-time, I’ve learned that (for myself, at least) mental breaks are needed in order to re-approach a challenge. Today, I’m going to let everything that happened yesterday and the night before sink in. I’ve also come to accept that my most-likely route will involve me disconnecting everything and starting fresh, from the beginning.

It’s funny how this reminds me a lot of my creative work; when my novel or short-story draft reached it’s own “dead end” (creative error code?) I did the same thing: learn from it, and start over.

This is probably why my husband says I’m the right type of detailed-oriented and determined (translation: obsessive and a little crazy) for this field.

I’m used to spending hundreds of hours on a writing project, just to find out that something in its approach is fundamentally wrong and needs to be reworked. So instead of that deterring me, I’m actually very used to it. For example, I’ve spent the past three years in graduate school re-writing one novel, from different perspectives. I must have written at least a thousand pages by now between drafts and re-writes. That does not include the amount of drafts I have written since high school, during undergrad and afterwards of other writing projects.

With that being said, as I let yesterday’s lessons absorb into my mind, I’ll be flexing the other side of my brain today by writing my new thesis draft #9682967, but who can keep count? (Maybe I’ll make that into a program one day: a draft counter that will tell me exactly how many pages I’ve written between all of my combined documents).

Lastly, it has been really nice to engage with the community more through online sources. It’s been intimidating to “expose myself” as such a new beginner, and I definitely feel the fear of asking a dumb question, but I know it’s an important step regardless. Virtual hugs to all those who have commented on my questions with thoughtful responses! And, it was fun for me to see that I could actually hold up a conversation with people and utilize some of the new terms I’m learning.

I definitely went to sleep last night with error codes floating around my brain, but I’m happy to have woken up excited to try again!

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