ET Airspeed sensor protocol

[PulseFusion]

So does anyone know how to interface with the Eagletree Airspeed sensor yet?

There's a lot of discussion of I2C and addresses and registers etc but nobody seems to have been able to do it?

I want to be able to use the sensor to be able to sweep wings on an Su-24 Fencer proportional to airspeed and this thing is a really good sensor so I was wanting to use it.

Basically i want to be able to plug in a micro between this sensor and the wing sweep servo(s) and use the airspeed as an input.

So. I now have one:
'ETS Airspeed Microsensor V3'
rev on board: Micro V3 Rev B3

opening it up you can read the following off the parts:

Differential sensor: ETS-170 Airspeed
7 segment display: BL-S28E-11UHR-21
Micro: Microchip PIC16F677

My guess is that the micro is in place to poll the sensor and then hold the data such that the ET logger polls it and the airspeed sensor sends it as an I2C slave?

So how to get the data out of the airspeed sensor?

[FAKHREALAM]

So does anyone know how to interface with the Eagletree Airspeed sensor yet?

There's a lot of discussion of I2C and addresses and registers etc but nobody seems to have been able to do it?


Why even use Eagletree, You can use PIC32 or any PIC or any other as long it supports math.h, use the thread below, formula I used, comes form NASA. Good to go, you can buy the pcb or complete board just connect to SPI port or ADC. Put the value to formula and get you air speed. I am in process of building board with SPI, I2C, UART and seven segment display for under $40.00. Check this link, if u need eagle PCB layout its free.

http://www.rcgroups.com/forums/showthread.php?t=1081305

Fakhre Alam

[PulseFusion]

Interesting, yeah i was just going to use the eagle tree as it was what i had here handy...

thinking a bit more about it, it reckon i might just build one from scratch with an MPXV7002, i dont really need spi, if i'm going to drive the sensor itself i may as well put it straight into the adc of the micro... that way it cuts out a step.

and use the negative for altitude. with this sensor, the datasheet says +Vout and -Vout is that for the two halves of the sensor? are they both gauge or is it purely differential only? could i use -Vout for altitude and +Vout with the other for airspeed?

[ThermalSeeker]

I don't know the product but my guess is that if it's a differential pressure sensor for airspeed then the -V out is just that. It's a negative voltage proportional to the differential pressure, not an absolute pressure output that can be used for an altimeter. Take another look at the datasheet.

Mike


... with this sensor, the datasheet says +Vout and -Vout is that for the two halves of the sensor? are they both gauge or is it purely differential only? could i use -Vout for altitude and +Vout with the other for airspeed?

[PulseFusion]

http://www.freescale.com/files/sensors/doc/data_sheet/MPXV7002.pdf?pspll=1

yeah i dunno, if you have a look at page 8 it says there's a reference to style 1 and style 2... not sure what that means...

all good though as if i cant get altitude too i'm not fussed. i'm really only after airspeed anyway for the wing sweep.

it would seem kinda useless to output +v and -v equal and opposite to me?

[FAKHREALAM]

http://www.freescale.com/files/sensors/doc/data_sheet/MPXV7002.pdf?pspll=1

yeah i dunno, if you have a look at page 8 it says there's a reference to style 1 and style 2... not sure what that means...

all good though as if i cant get altitude too i'm not fussed. i'm really only after airspeed anyway for the wing sweep.

it would seem kinda useless to output +v and -v equal and opposite to me?

Its very simple, use style 2. MPXV3002DP, CASE 1351-01, my board also have just the sensor output, I will take the adc out. please email me at fakhre@rocketmail.com or pm me, its only for $15.00 without adc (sensor installed with connector and supporting parts). Up to u, u can make your own too, all needed info is present in that thread.

Fakhre Alam

[FAKHREALAM]

http://www.freescale.com/files/sensors/doc/data_sheet/MPXV7002.pdf?pspll=1

yeah i dunno, if you have a look at page 8 it says there's a reference to style 1 and style 2... not sure what that means...

all good though as if i cant get altitude too i'm not fussed. i'm really only after airspeed anyway for the wing sweep.

it would seem kinda useless to output +v and -v equal and opposite to me?

I answer all your questions in my last posting, if you need any help, let me know. The formula I wrote take pressure in kpa(+ve values only). You need to convert you adc value to kpa and pass to c function, it will return you speed MPH, KMH, KNOTS. I join this groups to learn and help.

Thanks.
Fakhre Alam