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Prop wash destroys the pressure readings.
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Hi @Arnold
I have the sensor in the little white radiation shield on the top of the mast in this picture.
From lots of flights I worked out the sensor needs to be at least a blade diameter above the plane of the blades. So if you run 12" blades, the mast needs to be at least that otherwise you get bad pressure values.
Also the mast needs to be as light as possible and as stiff as possible. Otherwise you can get lots of nasty pendulum effects which make it impossible to fly.
Let us know how you get on.
Cheers
Ian
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Not had any time past week or so @Gordon, been away working. Hope to be home again next week and get back on it.
The program and module code I posted as Gists above is my latest (links below). So if you want to take that and spend some time on it, you are more than welcome. My aim was to eventually replicate what Ian did with his Arduino example.
I just recently got the "Humidity Most Accurate" working as well, so only "Pressure" and "Pressure More Accurate" needs fixing although they look OK comparing my code with Ian's, the data sheet from Bosch and Bosch's code, so suspect a rounding issue or similar.
Current test prog is here
Current module code is hereOutput currently looks like this:
_____ _ | __|___ ___ ___ _ _|_|___ ___ | __|_ -| . | _| | | | | . | |_____|___| _|_| |___|_|_|_|___| |_| http://espruino.com 1v77 Copyright 2015 G.Williams >echo(0); ChipID : 96 CtrlMeas : 36 Measuring... . . . . Done !!! ---------------------------------------------------------- Temperature : 21.9 Humidity : 45.8583984375 Pressure (Suspect) : -126.86268593172 ---------------------------------------------------------- Pressure More Accurate (Suspect) : 85.15359374999 ---------------------------------------------------------- Temperature Most Accurate : 21.90582997486 Humidity Most Accurate : 45.85865386029 Pressure Most Accurate : 1006.10934649366 ---------------------------------------------------------- { "i2c": { "_options": { "scl": B6, "sda": B7, "bitrate": 100000 } }, "compParams": { "dig_T1": 28415, "dig_T2": 26397, "dig_T3": 50, "dig_P1": 37393, "dig_P2": -10875, "dig_P3": 3024, "dig_P4": 6654, "dig_P5": 13, "dig_P6": -7, "dig_P7": 9900, "dig_P8": -10230, "dig_P9": 4285, "dig_H1": 75, "dig_H2": 356, "dig_H3": 0, "dig_H4": 335, "dig_H5": 0, "dig_H6": 30 }, "t_fine": 112157.84947130654, "adc_t": 524245, "adc_p": 336661, "adc_h": 29806 } ----------------------------------------------------------Cheers
Ian
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Probably not much help, but I have run the main Espruino board, single I2C board for pressure, temp and humidity and NEO6 GPS all logging every second to microSD card for 24 hours (so little sleep) from a 1000mAh 3.7v LiPo with power to spare, though not much.
So assuming you can power down external kit while sleeping, battery requirements won't be huge I would have thought.
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@LawrenceGrif I don't know, never used them. Most do have time limits though.
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http://www.carphonewarehouse.com/sims/pay-as-you-go/pay-as-you-go-sims most come with call minutes and texts as well but fairly cheap.
GiffGaff do SIM deals with data only and can be topped up or contract starting at £5 for 500mb.
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OK, it's all working, sort of...
Couple of the values coming back are suspect but I need to go through each function and check each one to ensure it's doing the right thing. I suspect it is just some rounding issues or other gotchas going from C to JS.
Some output from my test rig:
_____ _ | __|___ ___ ___ _ _|_|___ ___ | __|_ -| . | _| | | | | . | |_____|___| _|_| |___|_|_|_|___| |_| http://espruino.com 1v76 Copyright 2015 G.Williams >echo(0); ChipID : 96 CtrlMeas : 36 Measuring... . . . . Done !!! ---------------------------------------------------------- { "i2c": { "_options": { "scl": B6, "sda": B7, "bitrate": 100000 } }, "compParams": { "dig_T1": 28415, "dig_T2": 26397, "dig_T3": 50, "dig_P1": 37393, "dig_P2": -10875, "dig_P3": 3024, "dig_P4": 6654, "dig_P5": 13, "dig_P6": -7, "dig_P7": 9900, "dig_P8": -10230, "dig_P9": 4285, "dig_H1": 75, "dig_H2": 356, "dig_H3": 0, "dig_H4": 335, "dig_H5": 0, "dig_H6": 30 }, "t_fine": 0, "adc_t": 525584, "adc_p": 335232, "adc_h": 30412 } ---------------------------------------------------------- Temperature : 22.33 Humidity : 49.2021484375 Pressure (Suspect) : -124.63193742510 Pressure More Accurate (Suspect) : -116.96609374999 Temperature Most Accurate : 22.32728913521 Humidity Most Accurate (Suspect) : NaN Pressure Most Accurate : 1009.19167457070 ----------------------------------------------------------Current test prog is here
Current module code is hereMore when I've had time to work the functions and improve the code a bit. But still happy for anyone to chip in with improvement ideas.
Cheers
Ian
Above it only needs to be twice the prop diameter.
Below is needs to the best part of 15 times that as the craft produces 7kg of thrust at full power.
While the craft is climbing, the sensors on the mast are in clean air.