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Re: [Paparazzi-devel] Booz Barometer R1, R2, and Rs Values?


From: Jayson MacKiddie
Subject: Re: [Paparazzi-devel] Booz Barometer R1, R2, and Rs Values?
Date: Sun, 28 Feb 2010 19:56:59 -0500

Hello Poine,

Much obliged! :) Thank you. Could I trouble you for an MPX 6115 part number? There are many options in the series and I'd like to make sure I've got it right. I've narrowed it down quite a bit, but I'm probably better off just asking.

Regards,
Jay


On Sun, Feb 28, 2010 at 7:41 PM, antoine drouin <address@hidden> wrote:
Don't populate the 24 bits ADC (U$9) and associated parts ( R38, R39,
R40, U$10, C33, C34)
We use the LPC2148 internal ADC, hence the variable offset amplifier

On Mon, Mar 1, 2010 at 1:24 AM, Jayson MacKiddie
<address@hidden> wrote:
> Hello Poine and David,
>
> Thank you! Poine, do you have values for R38, R39, and R40 in the adjustable
> voltage referance circuit to the -VREF terminal of the ADC? Or do I need to
> determine an appropriate value according to the MPX 6115 output at our
> altitude. I'd be happy with a value you're using at the moment and we could
> tweak things once we get ourselves flying.
>
> Regards,
> Jay
>
>
> On Sun, Feb 28, 2010 at 6:18 PM, antoine drouin <address@hidden> wrote:
>>
>> Hello
>>
>> There is a little scilab script  (
>> paparazzi4/trunk/hw/booz/baro_amp.sce ) which you can use to play with
>> the values of the resistors.
>>
>> The values on the schematics, ie
>>  R10 = 27e3;
>>  R5  = 390;
>>  R6  = 12e3;
>>  R20 = 560;
>>  R21 = 680;
>> gives you an altitude range of -500m:930m ( with ground pressure at
>> 1013 ) which is a bit silly
>>
>> You might want to lower R20, for example
>>  R10 = 27e3;
>>  R5  = 390;
>>  R6  = 12e3;
>>  R20 = 220;
>>  R21 = 680;
>> gives you an altitude range of -380m to 1530m which is a bit better (
>> you want the negative value if you want to be able to fly at sea level
>> on a high pressure day )
>>
>> There is a slightly better script in
>> paparazzi4/trunk/hw/lisa/pressure.sce which takes sea level pressure
>> into account ( the one in booz doesn't, feel free to improve it )
>>
>> Regards
>>
>> Poine
>>
>>
>>
>> On Sun, Feb 28, 2010 at 9:28 PM, Jayson MacKiddie
>> <address@hidden> wrote:
>> > Hello all,
>> >
>> > We have decided to add the booz barometer to our Booz main boards. We
>> > have
>> > the parts list but what are the values of R38=Rs, R39=R2, and R40=R1 in
>> > the
>> > adjustable voltage referance circuit to the barometer? Are they to be
>> > specified based on local altitude to take full advantage of ADC
>> > resolution?
>> > Regards,
>> > Jayson MacKiddie
>> >
>> > _______________________________________________
>> > Paparazzi-devel mailing list
>> > address@hidden
>> > http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>> >
>> >
>>
>>
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>
>
>
> --
> Jayson MacKiddie
>
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>
>


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