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Arduino thermometer with DS18B20 sensor
Creating a thermometer with Arduino, a DS18B20 temperature sensor, and a 7-segment display module.
I had a spare Arduino UNO and a DS18B20 temperature sensor and I decided to build an accurate thermometer (something I wanted to develop for a long time). As I wanted to be portable I attached a 9V battery to power the Arduino. To display the temperature I used a 3 digit 7-segment display module which has 3 74HC595 shift registers integrated and can managed only by 3 cables. I advice you to use the module and not 3 individual shift registers to avoid the soldering (too many connections must be made). I use 1 decimal point to display temperatures in Celsius except for temperatures below -9.9 (because I would need one more digit). So, the display shows temperatures from -99 to -10, then from -9.9 to 0.0 and then up to 99.0. As for the look I wanted to look a little wild and harsh, so I ended up to a walkie-talkie style (someone can say that it looks like a bomb). Personally, I love it.
PCF8574 chip, Python and Raspberry Pi 5
I2C communication in Raspberry Pi 5 with PCF8574 and Python.
On Raspberry Pi 4 I was using the Python library pcf8574-io for I2C communication using the PCF8574 chip. However this library does not work on the newer Raspberry Pi 5. To be accurate, you can install it in RPi 5 using pip3 in a virtual environment (venv), however in my case I wanted my script to run as a service in global scope. So a virtual environment was not a choice. Most of the PCF8574 related code I found on the internet was outdated for Rpi4. After some search I found a Python library from jhaubrich on github which actually works. In this article I will give you a how-to guide for having I2C communication with PCF8574 chip and Python on Raspberry Pi 5. I access Raspberry from a terminal window using SSH (use PuTTY or other client).
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Projects
Projects completed
IOS Hotels v3.6
Charge per person, unique features, HTML emails, new payment methodsMarch 29, 2026IOS Rentals v4.0
Automatic coupon generation, software editionsFebruary 11, 2026IOS Reservations 6.0
Various improvements. Required for IOS Rentals 4.0+February 05, 2026IOS Rentals v3.8
Paypal checkout, diagnostic check and moreNovember 29, 2025Open Shop 4.0, 4.1, 4.2
Removal of inline events, Paypal Checkout, dialog messages, myPOSNovember 19, 2025IOS Rentals v3.7
Vehicle damages management, Digital client List support for AADE (Greek companies)June 28, 2025IOS Rentals v3.6
Export/import data, booking options, global overview and NBG.April 16, 2025IOS Hotels 3.5
Reviews, affiliates, IOS Sync, Global overviewMarch 29, 2025Open Shop 3.9
Improvements in shipping and payment methods as well as in orders management.February 28, 2025Affiliate bookings plugin
Plugins for Elxis and wordpress to display IOS Rentals affiliate reservationsJanuary 10, 2025
