PIC THERMOMETER FOR CHROME BROWSER
ARDUINO THERMOMETER FOR CHROME BROWSER
CH341 USB THERMOCOUPLE THERMOMETER 1024 °C
AHT21B SENSOR THERMOMETER USING CH341
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/downloads/CH341PAR_ZIP.html
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.
LCD THERMOCOUPLE THERMOMETER 1023 °C
Thermometer using
MAX6675 K type thermocouple module. 16x2 LCD display. Temperature range is 0-1023 °C with resolution of 1/4 degree. The MAX6675 SPI sends 2 bytes of data.
Software is for PIC16F1827 and PIC16F628A, circuit is for both PICs.
MAX6675 can be bought from eBay: https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2332490.m570.l1313&_nkw=max6675&_sacat=0
The LCD module has to be HD44780 compatible.
You are free to use the circuit diagram and the code with no
limitations.
THERMOCOUPLE THERMOMETER 1023 °C FOR PC
USB THERMOMETER FOR PC
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/sch/i.html?_from=R40&_trksid=p3519243.m570.l1311&_nkw=usb+to+uart
You are free to use the circuit diagram and the code with no
limitations.
USB THERMOMETER
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/USB_firm_eng.html
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.
Circuit Description
See also Technical Tips
PIC18F2550
Pin 3 is the analogue input. Input voltage range is +Vref minus
-Vref.
Pin 4 is the -Vref, Pin 5 is the +Vref, at 2.5V .
LM385 2.5 is a precision zener, equivalent can be used.
Pin 14 is 3.3V internal supply for the USB transceiver.
Pins 15,16 are the data lines to the USB connector on the PC.
Pin 20 is the PC 5V powering the PIC. It is limited to 100mA by
the PC. 0.47uF is for decoupling.
For USB wiring info: http://www.interfacebus.com/Design_Connector_USB.html
SENSOR
4 of 1N4148 diodes in series. When soldered with the diodes body next to each other you get small size sensor.
USB THERMOMETER USING DS18B20 SENSOR
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/usb.htm , http://openprog.altervista.org/USB_firm_eng.html
You are free to use the circuit diagram and the VB software with no
limitations.
Circuit Description
See also Technical Tips
PIC18F2550
Pin 14 is 3.3V internal supply for the USB transceiver.
Pins 15,16 are the data lines to the USB connector on the PC.
Pin 20 is the PC 5V powering the PIC. It is limited to 100mA by
the PC. 0.47uF is for decoupling.
For USB wiring info: http://www.interfacebus.com/Design_Connector_USB.html
DS18B20 SENSOR
Any type of case can be used. |