Atmospheric pressure and temperature measurement

[Vermes]

Presented device is a tool for pressure and temperature measurement based on digital converter MS5534 from Intersema Sensoric.

Elements of the construction:

• converter MS5534
• processor PIC16F628
• LCD display 2x 16 characters
• two capacitors
• LED
• mounting potentiometer (to adjust the display contrast)

Program which controls the converter and the LCD display was written in C for Microchip processors. Documentation of MS5534 (with control algorithms and examples of procedures used to write the converter control application in a version for PC parallel LPT port) was useful during writing the program.
In order to make the construction easier, processor PIC16F628 was used. It can work with internal 4MHz oscillator. Also there is a built-in PWM generator of the processor, which clocks the converter MS5534 by 32kHz signal.

Two programs were made. First of them (in resulting version ms5534_rej.hex) reads the content of calibration registers of the MS5534 and displays their value on the LCD display. When you know the value of the calibration registers, you can compile another program (ms5534_lite.c) based on them, which displays pressure and temperature. After a small mofication of the program, the device can function as a barometric altimeter.

The converter system must be powered with a voltage no greater than 3,3V, so adjustment of control voltages was carried out as follows:

System MS5534 and the processor are powered by a voltage of 3,3V, obtained after reducing the supply voltage by connecting a LED in series with a voltage drop of about 1,7V. The LCD display works with 5V power voltage. Despite the differences of the supply voltage of the processor and the display, the system works properly.

The device can be even more simplified by replacing a LED with a jumper, and powering the system with 3V, when your display has low operating voltage.

This simple system can be mounted on a universal board.



Link to original thread (useful attachment) – Pomiar ciśnienia atmosferycznego i temperatury wersji lite