Serial thermometer using transistor as a temperature sensor and MCP3201. Included Visual Basic 6 code and a circuit diagram.
The MCP3201 is a micro-power 12 bit analogue to digital converter. The supply to the circuit is via the 12V at pin 7 that is switched to logic high by the software (RTS enabled).
The communication to the PC is bit banging the Hardware Controls, the DTR is used for clocking the ADC and the CTS is used for data input.
NPN transistor with the collector and the base linked makes linear temperature sensor, the junction voltage changes at 2.25mV/centigrade with a negative coefficient. For quicker response use a small package i.e. TO92.
CALIBRATION: The calibration of the sensor and other components in the circuit is done in the VB application. When you start the VB application for the first time it creates a text file 'cal.txt' in the same folder. The file has 2 numbers that represent the sensor readings at 0 and 100 Centigrade. Because the voltages of different sensors vary it needs recording the voltages of the sensor in use. Record the voltages this way:
1. Cool the sensor to temperature near zero, ice mixed with water is 0 centigrade.
2. Click the 0 °C button, the application will update the file 'cal.txt' with a new value of the sensor reading.
3. Use boiling water to heat the sensor to 100 centigrade
4. Click the 100 °C button to update 'cal.txt' file with the new value.
You can read more about serial interface in http://www.beyondlogic.org/spp/serial.htm
Data sheet for the MCP3201 can be downloaded from here. LTC1285, ADS7822 are direct replacement to MCP3201.
VB6 code download. You are free to use the circuit diagram and the VB software with no limitations.

MCP3201
Pin 2 is the analogue input. Input voltage range of +Vref (about 1 V) is equal to digital 4096.
Pin 1 is the +Vref =1V . 10K and 2K7 metal film resistors will give better temperature stability.
Pin 8 is the 5 V supply to the IC. LP2950 is a Low Dropout 5V regulator, you can use either LP2950ACZ-5 or TS2950CT-5 or LM2931Z-5 or equivalent.
Pin 6 is the serial data out of the ADC, BC237 and BC327 are a level shift from 0-5V to -8 to +8V which is the voltage required for the serial connector.
Pin 7 is the clock for reading the data and pin 5 is the Chip Select. The 22K resistors are for lowering the 12V out of the serial port to 5V level of the ADC.

SENSOR
MTS102 could be hard to find, but any NPN transistor, TO92 or smaller package will give good response.

Serial thermostat using transistor as a temperature sensor and MCP3201. Included Visual Basic 6 code and a circuit diagram. The MCP3201 is a micro-power 12 bit analogue to digital converter. The supply to the circuit is from external 12V .
The communication to the PC is bit banging the Hardware Controls, the DTR is used for clocking the ADC and the CTS is used for data input. RTS at pin 7 is the drive for the relay. The relay changes when temperature is more than 0.5 degree from the set temperature.
NPN transistor with the collector and the base linked makes linear temperature sensor, the junction voltage changes at 2.25mV/centigrade with a negative coefficient. For quicker response use a small package i.e. TO92.
CALIBRATION: The calibration of the sensor and other components in the circuit is done in the VB application. When you start the VB application for the first time it creates a text file 'cal.txt' in the same folder. The file has 2 numbers that represent the sensor readings at 0 and 100 Centigrade. Because the voltages of different sensors vary it needs recording the voltages of the sensor in use. Record the voltages this way:
1. Cool the sensor to temperature near zero, ice mixed with water is 0 centigrade.
2. Click the 0 °C button, the application will update the file 'cal.txt' with a new value of the sensor reading.
3. Use boiling water to heat the sensor to 100 centigrade
4. Click the 100 °C button to update 'cal.txt' file with the new value.
You can read more about serial interface in http://www.beyondlogic.org/spp/serial.htm
Data sheet for the MCP3201 can be downloaded from here
VB6 code download. You are free to use the circuit diagram and the VB software with no limitations.

The serial port drives and powers PIC16F870. 4 analogue inputs, 6 digital inputs and 6 outputs are serially interfaced between the PC and the PIC. Included a VB6 software, Visual Studio 2005 C# code, PIC C code and a circuit diagram. The application transmits 1 byte of PIC outputs data and receives 9 bytes of data from the PIC.
The PC application can be changed or replaced if the inputs or outputs are to drive other software on the PC.
You can read more about serial interface in http://www.beyondlogic.org/spp/serial.htm
VB6, C#, PIC code and circuit diagram download. You are free to use the circuit diagram and the VB software with no limitations.

LCD TFT is digital display at its best, it displays versatile clear picture. The picture is built by entering the address and the color of a pixel or rectangle, so it's simple to use too.
LCD TFT to display text using PIC16F876A . Included C code and circuit diagram. The LCD TFT module is a 1.8" 128 X160 pixel. The LCD is driven by SPI.
The text is sent to the TFT via the serial port. Each character is 8x12 pixels stored in the VB6 application; there is no memory enough in this pic for the data. For each character the VB transmit 12 bytes.
LCD TFT modules vary depending on the drive IC. The module in the project has the driver ST7735 . I bought this module directly from China because the price was more sensible.
Code was written on MPLAB and compiled with the free HI TECH C compiler V9.80
Software includes PIC code. You are free to use the circuit diagram and the software with no limitations.

The serial port drives and powers an LCD module of 16X2 characters. Included a VB6 software, PIC C code and a circuit diagram. The VB application transmit only the last input byte to avoid overflow of the receive register of the PIC16F628A.
The serial port can source about 4 mA which is enough to drive the pic and the LCD module. The serial port can't power LCD with LED back light.
You can read more about serial interface in http://www.beyondlogic.org/spp/serial.htm
VB6 code, PIC code and circuit diagram download (20KB). You are free to use the circuit diagram and the VB software with no limitations.

This project is for connecting analogue signal to serial port. Included a VB6 software, PIC assembly, C code and a circuit diagram. The PIC12F675 micro controller is programmed to convert the analogue input to 10 bit digital and transmit it in UART protocol to the serial port. The microcontroller is powered by the signals of the serial port, so no external power supply is needed.
You can read more about serial interface in http://www.beyondlogic.org/spp/serial.htm
Software includes PIC code and VB6 code (20KB). You are free to use the circuit diagram and the software with no limitations.