Show pageOld revisionsBacklinksBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ====== Tire Pressure Sensor ====== The pressure is determined by the formula, <m>P=0.145*{{{ADC/2^10}-0.04}/0.0012858}</m> where ADC is the value from the 10-bit DAC and P is the pressure in PSI. The pressure sensor is ratiometric with respect to V<sub>dd</sub> which makes it easy to interface to the PIC. Instead of the LCD display the finished project will use the [[7segdisplay]] to make it easier to read under different lighting conditions. Also, I have not been able to locate a small, backlight display, or even a small single line display that is inexpensive. ===== Prototype ===== {{:projects:electronics:tirepressuresensor:pconbrdtop.jpg?300|}} {{:projects:electronics:tirepressuresensor:pconbrdbottom.jpg?300|}} {{:projects:electronics:18f_control_board.jpg?300|}} {{:projects:electronics:18f_control_board_etch.pdf|}} ===== Parts ===== ^ Part# ^ Description ^ Source ^ Cost ^ |MPX5700DP-ND|0-101.5PSI Pressure sensor|[[http://www.digikey.ca/|Digikey]]|$16| | |2 Ft 1/4ID hose|Home Hardware|$1.50| | |2 crimp style hose clamps|Home Hardware|$1.60| | |Barbed hose connector|Home Hardware|$1.19| | |Compression fitting|Home Hardware|$1.95| | |Street Elbow|Home Hardware|$2.29| | |Barbed hose connector|Home Hardware|$1.19| | |Click on air chuck for valve stem |Princess Auto|$3| | |1/8NPT tank valve|Princess Auto|$2.50| | Total ||| $<php>print 16+17;</php> | ===== Development ===== Here are the {{:projects:electronics:excel_calculations.pdf|calculations}} I did for the module using a spreadsheet to graph the transfer function, then working out the math to something which can be easily done in assembly. {{:projects:electronics:mpx5700.pdf|MPX5700 Datasheet}} {{:projects:electronics:p1020101.jpg?300|}}{{:projects:electronics:7segdisplay:display_working.jpg?300|}} projects/electronics/tirepressuresensor.txt Last modified: 2014/11/13 10:50by 127.0.0.1