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Found 1 result

  1. I have to mention RobG and cubeberg have helped with this. THANKS!!!! What it is, is one pressure sensor affecting two, 16 bit DAC output channels. What it will do (hopefully ;-)) is read an (automotive) industry standard MAP (manifold absolute pressure) sensor- in this case an MPX4250A 20-250 kPa (kilo Pascal) / 2.9-36.3 PSI sensor (~100 kPa / 14.7 PSI is ambient pressure at sea level), and appear as up to two potentially different sensors. Possible uses could include: replacing obsolete MAP sensors with more readily available ones because of different output range / scaling; fooling a vehicle's engine control unit to allow for bigger injectors or turbocharging; splitting one MAP signal for two purposes; or affecting pressure controlled devices. The aforementioned MAP sensor will be connected to whatever vacuum / pressure source. The MCU will sample that and generate an output. But instead of doing a mathematical conversion, there will be look-up tables. This will permit non-linear adjustments to be made, allowing for compensation factors to be applied to the output, tuning. What I am uploading now, is a Booster Pack version of this, which should be usable with MSP430 and Stellaris/Tiva LaunchPads. Eventually, I want to have a complete stand-alone, with software to interface with it from a PC. I think we are close to that too; but still some details to work out. Hardware is: - MPX4250AP absolute pressure sensor- http://www.freescale.com/files/sensors/doc/data_sheet/MPX4250A.pdf - AD8644A quad op-amp- http://www.analog.com/static/imported-files/data_sheets/AD8614_8644.pdf - LTC2602IM dual-channel, 16 bit DAC- http://cds.linear.com/docs/en/datasheet/2602fa.pdf - 25AA512 eeprom- http://ww1.microchip.com/downloads/en/DeviceDoc/22021F.pdf - supporting resistors, capacitors, do dad's and whatnot's. Should probably mention I have added jumpers to disconnect V+ from either of the output sensor connections... the board is meant to be connected to the sensors and use their 5V+ to power the op-amp and provide external voltage reference for the ADC, but on my motorcycle one of the sensors has 12v and an internal voltage regulator. Therefore, I put the jumpers in so any sensor with inappropriate V+ could be kept out of the system. I've also put a jumper between the 5v from the sensors and the 3.3v LDO so that the LDO can be disabled if the LaunchPad is operating off USB. I do not have any presentable code to offer at the moment but am working on it; suggestions will be appreciated... and I'm working in Energia, which might have been evident with my post in the Energia forum: http://forum.43oh.com/topic/4292-multiple-slaves-on-spi/, so be kind. ;-) SingleBP.brdSingleBP.sch Comments and suggestions greatly appreciated. * Please ignore the name "SingleBP". I used that because the 500T version of my motorcycle uses 4 MAP sensors, and the 650T uses two. So "Single" means one unit needed for the 650T.
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