Category: Uncategorized

For most private homes in my area a good and quick internet is a challenge, optics is not an option most of the time and only quick connectivity I am left with is 5G (which is not a bad option). Problem with this choice that windows facing 5G tower are on 2nd floor and I have to figure way how to deliver wired connection from 2nd floor where 5G router is located to the 1st floor where all home devices are connected.

I have found out that there is option to use adapters connected at both ends of coax cable to pass through Ethernet connection at claimed speeds reaching 1Gb. This sounded great, because I have coax cables going all through the house, this allows me to have 5G router connected to one end of coax cable and the other end connected to the rest of existing home network, connecting both floors by wire.

According to labels on the box adapters should be able to reach 1 Gb/s speeds and I wanted to test this out. iPerf application can be used to measure maximum achievable bandwidth on your network. For this to work you have to set up a server on one of the devices you are testing connectivity and on the other device you are using as client and application is evaluating bandwidth speed between those two devices.

I did a few tests, first I tired measuring what are speeds passing throughout coax cable and best speeds I have achieved was 285 Mbits/sec although between two points that are connected by LAN I have measured over 900 Mbits/sec

Conclusions

I am satisfied with the speeds I have managed to measure, although manufacturer is noting that adapters are capable reaching 1 Gigabit speeds, there can be different reasons that can have an affect on decrease for bandwidth speed. Still being able to get up to 285 Mbits/sec from 2nd floor to the 1st, where I have all the devices linked is more than enough as it is unlikely that my internet connection will be getting up to that limit.

I have started building this prototype to automate carbon fiber tube winding process. Currently at the end of the task I have to apply shrink-tape by manually holding the roll in hand and guide that along the mandrel. Significant improvement would be applying same tape using machine gantry which is feeding the tape on mandrel with constant force. For constant feeding force I would need drag torque on shrink-tape roll axis.

Unfortunately my attempt described in this post failed and I will have to look for another option, anyway it was interesting to fail and now it is more clearer.

Before I was starting building prototype I did calculations to estimate needed torque to hold required tension force. Although stepper used for this prototype does not hold needed torque, my intention here was to test the idea. Another benefit that I expected to have with this variant was some degree of control when variable resistor is connected to motor wounds and when resistance is changed torque changes. A day before I have experimentally found needed resistor range which was from 0 ohms to 500 ohms.

All calculation values were captured and a graph was drafted where on Y-axis you can see calculated torque value. When tube is wound shrink-tape roll diameter changes what gives torque increase and different color lines represent different tension forces for different diameters when tape is unwinding.

Afterwards CAD model was created with Fusion 360 and parts produced using some plastic material laying somewhere in workshop. Here below is fabricated one of the pulleys.

When all was assembled I could give it a try, after light pull I understood that idea has failed. Braking unit was not holding torque, as I was pulling the tape, I was feeling some resistance, but as I increased speed torque disappeared and it started to slip. I had a slight doubt that this could happen, but I was hopeful. It worked for small speeds, but was not working for my application.

Concept was tested and showed not to be working for this application, I have feedback now, I can readjust and attempt another option. Now I am thinking of making a torque motor with large diameter with opposite rotation direction. Have to do some calculations, some search and thinking. Till later!

I am currently working on a project related with smart home and for my use-case I have chosen Siemens Logo 8 controller as a main brain device. One thing that I like very much about this Logo generation over previous, that it comes with integrated Modbus TCP functionality. This is very useful, because instead of interfacing with device using digital inputs and outputs I am able to transfer flag and numeric values through Modbus TCP connection to any device which is supporting this protocol. This helps building custom HMI with specific functionality or expand with custom peripheral devices or connecting industrial equipment through Modbus TCP.

My setup consists of Logo 8 controller together with 24V power source. Using Ethernet cable it is connected to home TP 10/100 switch which is linking Raspberry Pi LCD and my laptop.

For Logo I have added 7 input buttons and one analogue input which is connected to variable resistor, for now all relay outputs are not connected to anything, but their operation can be spotted by sound which is made when contact is made and that is enough for me at this point.

To interface with Logo device I am using Python library uModbus that creates connection and is communicating values between devices. With Python I am changing or reading specified memory section which is reserved on Logo, all memory mapping information can be found in Siemens Logo datasheet.

In Logo program above I have added digital Input M1 which is changed from Modbus TCP client (in this case Raspberry Pi) and then turning on/off the relay. Modbus TCP packets can be transferred ower ordinary Ethernet network.

Following code is taken from uModbus description page example code and adjusted for my setup. In example above I am reading analogue value from my A1 (analogue input 1), when variable resistor is turned, then changed value is reflected on Python console screen. Below Python code example.

Reading analogue values code example

import socket
from umodbus import conf
from umodbus.client import tcp
from time import sleep as wait

# Enable values to be signed (default is False).
conf.SIGNED_VALUES = True

### Creating connection
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(('192.168.0.3', 502))

### Reading Analogue value from associated Input Register
message = tcp.read_input_registers(slave_id=1, starting_address=0, quantity=1)

### Printing analogue values in Python console
for i in range(1, 100000):
    response = tcp.send_message(message, sock)
    print(response, i)
    wait(0.01)

sock.close()
print("Transfer ended!")

Setting Logo coil value code example

import socket
from umodbus import conf
from umodbus.client import tcp

# Enable values to be signed (default is False).
conf.SIGNED_VALUES = True

### Creating connection
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(('192.168.0.3', 502))

message = tcp.write_multiple_coils(slave_id=1, starting_address=8256, values=[1, 0, 0, 0])

# Response depends on Modbus function code. This particular returns the
# amount of coils written, in this case it is.
response = tcp.send_message(message, sock)
print(response)
sock.close()
print("Transfer finished")

In conclusion – Modbus TCP functionality in Logo controller is very powerful thing, that expands Siemens Logo controller integration with different devices that are supporting this interface. It gives you more flexibility in choosing peripherals and one can develop own HMI solutions.

One thing that I have not added to this stage of the project was VPN connectivity to this workbench. For that I am missing router that is supporting PPTP connectivity. PPTP client connection would enable controlling this setup remotely from any part of the world, this enables monitoring different statuses of logs, capturing and storing different analogue and flag values in database.

For easier Python code transfer to Raspberry Pi I suggest setting shareable folder on Raspberry Pi that can be accessed on devices on local network.

Source

• Python Modbus TCP library used – https://pypi.org/project/uModbus/
• Shareable Folder on Pi – https://raspberrypihq.com/how-to-share-a-folder-with-a-windows-computer-from-a-raspberry-pi/
• PPTP – https://en.wikipedia.org/wiki/Point-to-Point_Tunneling_Protocol

This was a quick project making a Bluetooth audio box for the workshop, because old radio device was drifting away from station all the time. It took me some time to ripe for this as it is time consuming and costs extra money to get speakers, power unit and some buttons. The audio Bluetooth module has been laying around for some time already on the table waiting for the right moment.

Initially it was planned to add a USB fast charging port, but it took too long to arrive and I have skipped this idea, but if you plan to replicate same you definitely should add one, then you can charge your phone while listening to music.

In this post I have listed some images on how it was made and box drawings as well as list of components used, in case you plan to replicate the same.

Link to drawings of box assembly.

Components:

• Bluetooth audio module – eBay link
• Power source 24V 4.5A – https://www.lemona.lv/?page=item&i_id=215500
• 30 W speakers – https://www.kenwood.eu/car/speakers/e_series/KFC-S1366/?view=details
• 5x NO Switches
• 9 mm plywood
• Main switch – had one laying around
• Main 220 V wire
• 3 mm plastic for back palate

If you need additional information, other drawings or assembly file do not hesitate, let me know.

Already some time ago I have purchased Raspberry PI zero w a small computer with WiFi connectivity and I have paid for it not more than 20 EUR together with shipping, it is small but with rich number of applications. In this case I came up with an idea to build IoT that will be logging environment at my workshop and all will be neatly displayed in Google spreadsheet.

When I was starting winter was just coming and with such device I could monitor temperature in workshop and if it drops below some certain point I will know that I have to turn on heating. Data is being written in Google spreadsheet it is possible to add Google Apps scripts and receive notifications if a certain condition is met, then you will never miss when heating has to be turned on.

To add some senses to my “Zero” device I have added to it Enviro Phat then by importing python library I was able to read temperature, light and pressure values, but it was missing humidity readings. For humidity readings I am using DHT22, which gives humidity value together with temperature value.

To give assembly some structure and protection I have decided to enclose electronics with poly-carbonate sheets. Parts was milled on my router here below from material which was laying in workshop.

For this project I have chosen to have simple protection for the electrical components stacked them in poly-carbonate layers.

This is how all looks together. One note here, initially I had difficulties with temperature readings because when Raspberry PI and Enviro Phat are stacked closely together it gives wrong temperature readings due to small proximity of pi chip. During normal operation it heats up so in normal room temperature reads about 35 C degrees, that is why it was needed to increase distance between these components and I have used middle poly-carbonate part to minimize error.

So when hardware is in place i can proceed with developing python code for the device.

In python I have written code that every 30 min reads environment variables and writes these values in google spreadsheet. To set up Envro Phat it was necessary to import its library. Details on how to do that are here. And for DHT22 have installed this library. To ensure that my script is executed with 30 min frequency I am using crontab that launches python script every 30 minutes and command for that is:

00,30 * * * * (cd ~/Environment/factory/ && python environmentLog.py)

crontab -e

Use command: pip install gspread oauth2client

End words

have been reading MIT Technology Review newsletter for some time already and it would be more convenient to read news on my Kindle device, but to do that I need manually load files to device and that is much work to do. Challenge was spotted, I have to automate this!

What is needed?

1. Kindle device;
2. Subscription to a newsletter (it can be any subscription, because script is creating HTML file from message body);
3. Account in Google mail;

My first approach was to subscribe Kindle email directly to newsletter, but it failed because this mail is used to send documents in range of formats not plain email text  and all mails were rejected, I learned that i have to send files. One of formats accepted by Kindle is *.html, that was good news because message bodies contain html tags I only need to pack all content in html file. Solution here was to use Google script to retrieve emails one by one, then create from message body html file and then send it to kindle. As easy it sound here as easy it was to accomplish that.

Script reads emails from designated folder converts message body to *.html file which is sent to Kindle email. Then message is deleted as well as file from Google drive. I have not seen any newsletter they all are handled now they are piling up in my Kindle device. Script has one function to which trigger has been set  to run it in mornings from 6:00 to 7:00.

function send2Kindle() {

   var label = GmailApp.getUserLabelByName(“MIT newsletter”);//Folder name in email mails are read.

 var threads = label.getThreads();

   var emailTo = “your_kindle_mail@kindle.com”, subject;

 var msgStart1 = “<html><head><title>”, msgStart2 = “</title><head><body>”, msgEnd = “</body></html>”; //Had to add these tags for html file for Kindle to recognise that this is HTML file.

 // Getting newsletter

 for (var i = 0; i < threads.length; i++) {

   var msg = threads[i].getMessages(), subject = msg[0].getSubject(), body = msg[0].getBody();

   //Creating the file

   var letterFile = DriveApp.createFile(subject + ’.html’, msgStart1 + subject + msgStart2 + body + msgEnd, MimeType.html);

   //Sending mail

   MailApp.sendEmail(emailTo, subject, ‘Have a goood read! Kind regards!’, {attachments: [letterFile]});

   //Removing file

   DriveApp.removeFile(letterFile);

   //Removing message

   GmailApp.moveThreadToTrash(threads[i]);

 }

//END

}

In my mail account all newsletters from MIT Technology review are stored in separate folder and archived, I don’t even see them in my inbox. At the bottom I have picture illustrating that. Basically this folder is empty all the time because it is cleared in mornings.

This is  device I am using,  it may be old but I like the design of it. This Kindle does not have a touchscreen, sometimes it may be frustrating to write a WIFI name together with password using only 5 buttons.

Results: Google script successfully picks up newsletters and creates *.html file and then it is sent to Kindle email as a document attachment. Then Kindle is able to load file and lastly I am able to read news. Hope this was helpful to you, cheers!