Topics

new 3-day graph of barometric pressure


Barry Hansen
 

New feature: a graph of barometric pressure over the most recent 2-3 days is now built in to the main Griduino program v0.32.

Visit Griduino/downloads to read the changelog and download griduino_v032.uf2.

To install the new firmware see the Programming instructions.

The air-pressure graph will automatically scale itself to the measurements; the graph always looks pretty lively but that’s because it expands the peaks and valleys to fill the vertical space. Give it a few hours or days to collect data and see the graph emerge. Note that its days and times are in GMT.

A picture containing chart

Description automatically generated

I’d like to hear about any bugs, usability quirks or feature requests, thanks!

Icon

Description automatically generated
Barry Hansen K7BWH

griduino@...
barry@...


Mihai W4MHI
 

Super cool! I tried to determine altitude and I find it very hard. 
This is really nice. 

73,
Mihai (W4MHI) 


-------- Original message --------
From: Barry Hansen <barry@...>
Date: 2/3/21 5:37 PM (GMT-08:00)
To: Griduino@groups.io
Subject: [Griduino] new 3-day graph of barometric pressure

New feature: a graph of barometric pressure over the most recent 2-3 days is now built in to the main Griduino program v0.32.

Visit Griduino/downloads to read the changelog and download griduino_v032.uf2.

To install the new firmware see the Programming instructions.

The air-pressure graph will automatically scale itself to the measurements; the graph always looks pretty lively but that’s because it expands the peaks and valleys to fill the vertical space. Give it a few hours or days to collect data and see the graph emerge. Note that its days and times are in GMT.


I’d like to hear about any bugs, usability quirks or feature requests, thanks!


Barry Hansen K7BWH

griduino@...
barry@...


Barry Hansen
 

Computing altitude from the barometer really is very hard. The underlying equation is complicated and nonlinear. Fortunately, the necessary algorithm is built into the Bosche BMP388 sensor and it compensates for temperature automatically and reports altitude directly. All I have to do is tell it the current sea level pressure, like this

              altitudeMeters = baro.readAltitude(gSeaLevelPressure);

 

The fun part is to compare the barometer’s altimeter to the GPS hardware’s altimeter. Hilarity ensues. The GPS’s reported altitude is variable according to the whirling overhead satellites. My house is about 35’ asl but my GPS reading swings from +300’ to -50’. The negative results are a little disconcerting when I’m practically at Lake Washington’s level already.

You can try it yourself. I wrote an example program; download it from GitHub at examples/Altimeter and compile it. A sample screen shot is below. Use the up/down buttons to adjust the barometer’s reading.

I’d like to write altimeter features for SOTA Activation Zones but I’ll need to work this out very carefully.

 

Barry Hansen K7BWH

barry@... and griduino@...

mobile 425-503-5548

Seattle, WA  CN87us

 

Graphical user interface, chat or text message

Description automatically generated

 

From: Griduino@groups.io <Griduino@groups.io> On Behalf Of Mihai W4MHI via groups.io
Sent: Wednesday, February 03, 2021 6:17 PM
To: Griduino@groups.io
Subject: Re: [Griduino] new 3-day graph of barometric pressure

 

Super cool! I tried to determine altitude and I find it very hard. 

This is really nice. 

 

73, Mihai (W4MHI) 

-------- Original message --------

From: Barry Hansen <barry@...>

Date: 2/3/21 5:37 PM (GMT-08:00)

Subject: [Griduino] new 3-day graph of barometric pressure

New feature: a graph of barometric pressure over the most recent 2-3 days is now built in to the main Griduino program v0.32.

Visit Griduino/downloads to read the changelog and download griduino_v032.uf2.

To install the new firmware see the Programming instructions.

The air-pressure graph will automatically scale itself to the measurements; the graph always looks pretty lively but that’s because it expands the peaks and valleys to fill the vertical space. Give it a few hours or days to collect data and see the graph emerge. Note that its days and times are in GMT.

I’d like to hear about any bugs, usability quirks or feature requests, thanks!


Barry Hansen K7BWH

griduino@...
barry@...


Mihai W4MHI
 

I wrote a small program and yes, it is frustrated when I saw negative values. 
I will try your code and see how close I was. 

Thank you very much! 

73,
Mihai (W4MHI) 


-------- Original message --------
From: Barry Hansen <barry@...>
Date: 2/3/21 7:00 PM (GMT-08:00)
To: Griduino@groups.io
Subject: Re: [Griduino] new 3-day graph of barometric pressure

Computing altitude from the barometer really is very hard. The underlying equation is complicated and nonlinear. Fortunately, the necessary algorithm is built into the Bosche BMP388 sensor and it compensates for temperature automatically and reports altitude directly. All I have to do is tell it the current sea level pressure, like this

              altitudeMeters = baro.readAltitude(gSeaLevelPressure);

 

The fun part is to compare the barometer’s altimeter to the GPS hardware’s altimeter. Hilarity ensues. The GPS’s reported altitude is variable according to the whirling overhead satellites. My house is about 35’ asl but my GPS reading swings from +300’ to -50’. The negative results are a little disconcerting when I’m practically at Lake Washington’s level already.

You can try it yourself. I wrote an example program; download it from GitHub at examples/Altimeter and compile it. A sample screen shot is below. Use the up/down buttons to adjust the barometer’s reading.

I’d like to write altimeter features for SOTA Activation Zones but I’ll need to work this out very carefully.

 

Barry Hansen K7BWH

barry@... and griduino@...

mobile 425-503-5548

Seattle, WA  CN87us

 


 

From: Griduino@groups.io <Griduino@groups.io> On Behalf Of Mihai W4MHI via groups.io
Sent: Wednesday, February 03, 2021 6:17 PM
To: Griduino@groups.io
Subject: Re: [Griduino] new 3-day graph of barometric pressure

 

Super cool! I tried to determine altitude and I find it very hard. 

This is really nice. 

 

73, Mihai (W4MHI) 

-------- Original message --------

From: Barry Hansen <barry@...>

Date: 2/3/21 5:37 PM (GMT-08:00)

Subject: [Griduino] new 3-day graph of barometric pressure

New feature: a graph of barometric pressure over the most recent 2-3 days is now built in to the main Griduino program v0.32.

Visit Griduino/downloads to read the changelog and download griduino_v032.uf2.

To install the new firmware see the Programming instructions.

The air-pressure graph will automatically scale itself to the measurements; the graph always looks pretty lively but that’s because it expands the peaks and valleys to fill the vertical space. Give it a few hours or days to collect data and see the graph emerge. Note that its days and times are in GMT.

I’d like to hear about any bugs, usability quirks or feature requests, thanks!


Barry Hansen K7BWH

griduino@...
barry@...