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Thread: Share the data not the cells

  1. #1
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    Lightbulb Share the data not the cells

    I've been thinking about DIY electronics for a DIY rebreather project.
    Many commercial units share the cells with many controllers/handsets.

    I thought about using only one cell per display/controller. The HUD got one cell, the handset got one cell and the buddy display got one cell. No cells are shared.

    Data between displays/controllers are shared so each display/controller can show the PO2 from all 3 cells. If the data connection is totally lost you can still use all cells but have to check all displays.

    The data is shared via an optically coupled link in a star or a ring topology. Using low speed UART, SPI or I2C would be nice since they are integrated in many microcontrollers.

    External decocomputers can be attached to the system via a data to voltage converter. It has a IR receiver and converts the data to the millivolt range used in O2 cells. It either converts data from all 3 cells, one cell only or from the closest 2 cells.

    Any further ideas or comments?

  2. #2
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Share the data not the cells

    Very interesting idea. To go one step further (or backwards) if you are using a manual system the cell data does not even need to be shared it can be independent


    Quote Originally Posted by plazma  View Original Post
    I've been thinking about DIY electronics for a DIY rebreather project.
    Many commercial units share the cells with many controllers/handsets.

    I thought about using only one cell per display/controller. The HUD got one cell, the handset got one cell and the buddy display got one cell. No cells are shared.

    Data between displays/controllers are shared so each display/controller can show the PO2 from all 3 cells. If the data connection is totally lost you can still use all cells but have to check all displays.

    The data is shared via an optically coupled link in a star or a ring topology. Using low speed UART, SPI or I2C would be nice since they are integrated in many microcontrollers.

    External decocomputers can be attached to the system via a data to voltage converter. It has a IR receiver and converts the data to the millivolt range used in O2 cells. It either converts data from all 3 cells, one cell only or from the closest 2 cells.

    Any further ideas or comments?
    Cheers,

    Dave....

    www.wedivebc.com

  3. #3
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    Re: Share the data not the cells

    Quote Originally Posted by plazma  View Original Post
    I've been thinking about DIY electronics for a DIY rebreather project.
    Many commercial units share the cells with many controllers/handsets.

    I thought about using only one cell per display/controller. The HUD got one cell, the handset got one cell and the buddy display got one cell. No cells are shared.

    Data between displays/controllers are shared so each display/controller can show the PO2 from all 3 cells. If the data connection is totally lost you can still use all cells but have to check all displays.

    The data is shared via an optically coupled link in a star or a ring topology. Using low speed UART, SPI or I2C would be nice since they are integrated in many microcontrollers.

    External decocomputers can be attached to the system via a data to voltage converter. It has a IR receiver and converts the data to the millivolt range used in O2 cells. It either converts data from all 3 cells, one cell only or from the closest 2 cells.

    Any further ideas or comments?
    If the optical link is located within the loop, wouldn't the humidity induce condensation on the optics and cause connection problems?


    Best regards,
    SS

  4. #4
    RBW Member Mike_Eitel is an unknown quantity at this point Mike_Eitel's Avatar
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    Re: Share the data not the cells

    Hi
    My five cents

    Use an opam directly on each cell, sperated batteries .. and sharing is no problem. If you take low power opam... Cheep batterie last > 1 year.

    Optical.... do you have any expirience with water absortion of the fibre ??

    Mike

  5. #5
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    Re: Share the data not the cells

    Quote Originally Posted by Mike_Eitel  View Original Post
    Hi
    My five cents

    Use an opam directly on each cell, sperated batteries .. and sharing is no problem. If you take low power opam... Cheep batterie last > 1 year.

    Optical.... do you have any expirience with water absortion of the fibre ??

    Mike
    Agreed that opamps protect the input but don't opto isolators require less power, and have faster response time? I also thought opto isolators were sealed and were not effected by the ambient environment.
    Cheers,

    Dave....

    www.wedivebc.com

  6. #6
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    Re: Share the data not the cells

    I also believe that the thread opener referred to optical couplers that are enclosed in a plastic housing which is not affected by ambient pressure/humidity. Also what he meant about using opto couplers is to provide 100% physical separation between the circuits.Correct me if I'm wrong.

    VR

    Roland

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    RBW Member anarchista is an unknown quantity at this point anarchista's Avatar
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    Re: Share the data not the cells

    Quote Originally Posted by plazma  View Original Post
    Any further ideas or comments?
    It was fitting to start with the design assumptions of the whole structure.
    Ways of achieving the objectives are many,
    but the basis is the idea.

    How are you going to process information about the size ppO2 to signal the opening of the electromagnetic valve? There are many ways that is closest to you and why?
    Forget for a moment to change the dosage to hasten the ascent ppO2 setting in circulation, or with equations describing this process (is simple).

    greet rc (pozdrawiam rc)
    Last edited by anarchista; 9th May 2011 at 20:13.

  8. #8
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    Re: Share the data not the cells

    Quote Originally Posted by anarchista  View Original Post
    It was fitting to start with the design assumptions of the whole structure.

    Ways of achieving the objectives are many,
    but the basis is the idea.
    Did you learn English from reading fortune cookies?

  9. #9
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    Re: Share the data not the cells

    I'm interested to hear/read the opinion of the manufacturers,homebuilders, experts!

    VR

    Roland

  10. #10
    Just add ice & water plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma is a name known to all plazma's Avatar
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    Re: Share the data not the cells

    Quote Originally Posted by seasick  View Original Post
    If the optical link is located within the loop, wouldn't the humidity induce condensation on the optics and cause connection problems?
    There is two options. Sealed optocouplers or led+sensor. The first is sealed from environment and the latter may be affected by moisture or not. Testing required.

    Quote Originally Posted by Mike_Eitel  View Original Post
    Hi
    My five cents

    Use an opam directly on each cell, sperated batteries .. and sharing is no problem. If you take low power opam... Cheep batterie last > 1 year.

    Optical.... do you have any expirience with water absortion of the fibre ?
    You need 3x3=9 OP amps to separate them all and the GND stays common.

    Quote Originally Posted by rolanddiver  View Original Post
    I also believe that the thread opener referred to optical couplers that are enclosed in a plastic housing which is not affected by ambient pressure/humidity. Also what he meant about using opto couplers is to provide 100% physical separation between the circuits.Correct me if I'm wrong.
    Right. 100% physical separation and true independent monitors with the benefit of showing all cells is what I'm after.

    Quote Originally Posted by Andy T  View Original Post
    Did you learn English from reading fortune cookies?
    I bet he writes better English than you write Polish.

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