USB thermometer using DS18B20 as a temperature sensor. PIC C code and a circuit diagram.
The temperature can be displayed in Chrome, Edge and Opera browsers https://developer.chrome.com/ . Run the PIC connected via USB to Serial Adapter, open file web_thermo.html in the browser and click Connect. For temperature below zero the display is in blue. The html includes javascript.
USB-UART can be bought from eBay: https://www.ebay.co.uk/
You are free to use the circuit diagram and the code with no limitations.

USB thermometer using DS18B20 as a temperature sensor.
The temperature can be displayed in Chrome, Edge and Opera browsers https://developer.chrome.com/ . Run the Arduino connected to PC, open file web_thermo.html in the browser and click Connect. For temperature below zero the display is in blue. The html includes javascript.
Arduino lib. https://github.com/
You are free to use the circuit diagram and the code with no limitations.

CH341 module (from eBay) converts USB to I2C/SPI/EPP. MAX6675 K type thermocouple module. Temperature range is 0-1024 °C with resolution of 1/4 degree. The MAX6675 SPI sends 2 bytes of data.
PC app is in Visual Basic-VS2010. The module links are set to 5V and i2c-spi.
MAX6675 can be bought from eBay: https://www.ebay.co.uk/
The VB wrapping of DLL is taken from GitHub https://github.com/ . DLL is installed to PC by setup.exe in downloaded driver CH341PAR.ZIP https://www.wch.cn/

Thermometer using CH341 module (from eBay) converts USB to I2C/SPI/EPP. The module links are set to 3.3V and i2c-spi. The VB wrapping of DLL is taken from GitHub https://github.com/aa4e/ch341_vb . DLL is installed to PC by setup.exe in downloaded driver CH341PAR.ZIP https://www.wch.cn/
Temperature / humidity sensor AHT21b ranging -40 to 120. The CH341 sends measurement trigger and sensor sends back 1 byte of state, 5 bytes of data for temperatue and humidity and 1 byte CRC. Sensor accuracy is 1% for humidity and 2 degrees for temperature.
Ebay: https://www.ebay.co.uk
Windows app code is in Visual basic in freeVisual Studio 2010.

You are free to use the circuit diagram and the code with no limitations.

Thermometer using MAX6675 K type thermocouple module. Temperature range is 0-1023 °C with resolution of 1/4 degree. The UART module reads the 16 bits of data by bit banging the MAX6675. Supply of 3.3V to the MAX6675 is from the UART module.
Windows app code is in Visual basic in freeVisual Studio 2010.
The USB to Serial I used is: https://www.ebay.co.uk/
MAX6675 can be bought from eBay: https://www.ebay.co.uk/

You are free to use the circuit diagram and the code with no limitations.

USB thermometer using DS18B20 as a temperature sensor. Included VS2010 vb code, PIC C code and a circuit diagram. The PIC sends 2 bytes of temperature and the USB to UART opens a serial port in the PC. The VB app lets you select the active port.
Software is for PIC16F1827 and PIC16F628A, the VB app and circuit are for both PICs. Windows app code is in Visual basic in freeVisual Studio 2010.
USB-UART can be bought from eBay: https://www.ebay.co.uk/
You are free to use the circuit diagram and the code with no limitations.

USB thermometer using diodes as a temperature sensor. Included VS2005 C# code, PIC ASM code, PIC C code and a circuit diagram. The PIC microcontroller has 10 bit analogue to digital converter. The circuit is powered by the USB. The interface to the PC is HID class.
Diode make linear temperature sensor, the junction voltage changes at about 2.32mV/centigrade. The sensor is 4 diodes 1N4148 in series.
CALIBRATION: The calibration of the sensor and other components in the circuit is done in the PC application. When you start the application for the first time it creates a file 'cal.dat' in the same folder. The file has the actual temp entered by the user. Type the actual temp from another thermometer that you know reads correctly and press 'Calibrate'.
HID class (human interface device) is a class of devices like the mouse and the keyboard, the data transfer rate is limited to 64KB/S.
C# code is modified Microchip code from the USB framework, Microchip Solutions v2012-04-03.
The source code is derived from freeware from these sources: http://janaxelson.com/usb.htm , http://openprog.altervista.org/
Code was written on MPLAB 8x and compiled with C18 ver 3.30. PIC18F2550 was programmed using Velleman K8076.
Software includes PIC code and C# code. You are free to use the circuit diagram and the C# with no limitations.

USB thermometer DS18B20 temperature sensor. Included Visual Basic 6 software, Visual Studio 2005 C# code, PIC C code and a circuit diagram. The PIC interface to the PC is HID class.
The DS18B20 sensor has a range of -55 to 125 centigrade in accuracy of 0.5 degree and resolution of 9 to 12 bits. The interface to the pic is via one digital line, the 1 and 0 is determined by pulse duration. The code includes the commands to read temperature and set the resolution.
HID class (human interface device) is a class of devices like the mouse and the keyboard, the data transfer rate is limited to 64KB/S. The PC already has a driver for HID USB.
C# code is modified Microchip code from the USB framework, Microchip Solutions v2012-04-03.
VB6 code includes guidance to setting up the PC. The PC register the PID (Product ID) and VID (Vendor ID) of the USB device when it's plugged, the VB code uses these ID's to communicate with the device. For commercial VID it is needed to buy it from USB-IF, but in your lab you can use any number.
The source code is derived from freeware from these sources: http://janaxelson.com/ , http://openprog.altervista.org/
You are free to use the circuit diagram and the VB software with no limitations.