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| projects:electronics:tirepressuresensor [2008/04/14 21:42] – photonicsguy | projects:electronics:tirepressuresensor [2014/11/13 10:50] (current) – external edit 127.0.0.1 |
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| ==== Tire Pressure Sensor ==== | ====== Tire Pressure Sensor ====== |
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| 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. | 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. |
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| === Prototype === | ===== Prototype ===== |
| Coming soon | {{:projects:electronics:tirepressuresensor:pconbrdtop.jpg?300|}} |
| | {{:projects:electronics:tirepressuresensor:pconbrdbottom.jpg?300|}} |
| | {{:projects:electronics:18f_control_board.jpg?300|}} |
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| === Development === | {{:projects:electronics:18f_control_board_etch.pdf|}} |
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| | ===== 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> | |
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| | ===== 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. | 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. |
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| {{:projects:electronics:mpx5700.pdf|MPX5700 Datasheet}} | {{:projects:electronics:mpx5700.pdf|MPX5700 Datasheet}} |
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| {{:projects:electronics:p1020101.jpg|}} | {{:projects:electronics:p1020101.jpg?300|}}{{:projects:electronics:7segdisplay:display_working.jpg?300|}} |