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hamishcunningham / pi-tronics

Source code for Raspberry Pi GATE projects.
http://pi.gate.ac.uk/
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Voltage measurement starts at 5.07V - why is this? #35

Closed wayner9 closed 9 years ago

wayner9 commented 9 years ago

I have placed an A+ with a MoPI, a battery on one MoPi input and 2x3V solar cells (connected in series) on the second input. This Pi is in my greenhouse where the ambient temperature is very low right now - around -12C plus any heat generated by the sun. It looks like I get a reading of 0 from the input voltage of the solar cells until there is enough light to get the solar cells to 5.07V. Then I get valid readings until later in the day when the sun starts to set.

Is there a technical reason why voltage measurement starts at this level? Or was this a design choice? It might be nice to also read lower voltage levels when using solar cells.

hamishcunningham commented 9 years ago

the specified lowest operational voltage of mopi is 6.2V -- results that you might get below there are unpredictable! best h

On 3 February 2015 at 14:57, wayner9 notifications@github.com wrote:

I have placed an A+ with a MoPI, a battery on one MoPi input and 2x3V solar cells (connected in series) on the second input. This Pi is in my greenhouse where the ambient temperature is very low right now - around -12C plus any heat generated by the sun. It looks like I get a reading of 0 from the input voltage of the solar cells until there is enough light to get the solar cells to 5.07V. Then I get valid readings until later in the day when the sun starts to set.

Is there a technical reason why voltage measurement starts at this level? Or was this a design choice? It might be nice to also read lower voltage levels when using solar cells.

— Reply to this email directly or view it on GitHub https://github.com/hamishcunningham/pi-tronics/issues/35.

Hamish Cunningham Professor of Computer Science, University of Sheffield, UK +44 7920 765 455 http://twitter.com/@HCunningham hamish@gate.ac.uk http://pi.gate.ac.uk http://hamish.gate.ac.uk http://gate.ac.uk

wayner9 commented 9 years ago

Ok, thanks Hamish. My 15V solar cells arrived from China last night. I will be writing some code to log the voltage readings to a database and report through a web UI. Do you think this is something that other folks will find useful? If so where should I post it? Here at Github? Or is there a more centralized place where people can find MoPi related project?

hamishcunningham commented 9 years ago

yes, sounds great; if you want to do a draft in .mkd format I can post it on pi.gate.ac.uk ? best h

On 4 February 2015 at 14:43, wayner9 notifications@github.com wrote:

Ok, thanks Hamish. My 15V solar cells arrived from China last night. I will be writing some code to log the voltage readings to a database and report through a web UI. Do you think this is something that other folks will find useful? If so where should I post it? Here at Github? Or is there a more centralized place where people can find MoPi related project?

— Reply to this email directly or view it on GitHub https://github.com/hamishcunningham/pi-tronics/issues/35#issuecomment-72865313 .

Hamish Cunningham Professor of Computer Science, University of Sheffield, UK +44 7920 765 455 http://twitter.com/@HCunningham hamish@gate.ac.uk http://pi.gate.ac.uk http://hamish.gate.ac.uk http://gate.ac.uk

wayner9 commented 9 years ago

I am not familiar with mkd - I was going to have python code and a bit of textual documentation.

My code will be based off of these two web pages but will focus on logging voltage rather than temperature: http://raspberrywebserver.com/cgiscripting/rpi-temperature-logger/building-an-sqlite-temperature-logger.html http://raspberrywebserver.com/cgiscripting/rpi-temperature-logger/building-a-web-user-interface-for-the-temperature-monitor.html

hamishcunningham commented 9 years ago

cool -- mkd is markdown, which is used by github and others

but any format is ok really :-)

just let me know what you;d like to do! best h

On 4 February 2015 at 14:58, wayner9 notifications@github.com wrote:

I am not familiar with mkd - I was going to have python code and a bit of textual documentation.

My code will be based off of these two web pages but will focus on logging voltage rather than temperature:

http://raspberrywebserver.com/cgiscripting/rpi-temperature-logger/building-an-sqlite-temperature-logger.html

http://raspberrywebserver.com/cgiscripting/rpi-temperature-logger/building-a-web-user-interface-for-the-temperature-monitor.html

— Reply to this email directly or view it on GitHub https://github.com/hamishcunningham/pi-tronics/issues/35#issuecomment-72868689 .

Hamish Cunningham Professor of Computer Science, University of Sheffield, UK +44 7920 765 455 http://twitter.com/@HCunningham hamish@gate.ac.uk http://pi.gate.ac.uk http://hamish.gate.ac.uk http://gate.ac.uk