[PSUBS-MAILIST] instrument and environment display

Thu Jul 16 09:41:25 EDT 2015

Jon - sounds like an interesting project. I've never played around with any of those low cost / DIY solutions, but it sounds like they're rapidly closing the performance gap with true industrial systems.

At work, I do a lot of data acquisition and embedded controller development using National Instruments hardware, particularly on the CompactRIO hardware platform, which combines deterministic real-time processing with FPGAs for high speed low level I/O. I'd probably still be inclined to go that route (real-time vs pre-emptive OS) for a critical application (life support, excursion control, etc.), but the barriers to entry are high. The last small system I built was about $4000 for the controller and FPGA, exclusive of I/O modules.

Accessible technologies like BASIC stamps, Arduinos and Raspberry PI are generating a ton of impressive DIY projects these days, and might be perfect for a PSub.

Sean

On July 15, 2015 9:25:04 PM MDT, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>Steve,
>
>An arduino microprocessor captures the data from various sensors and 
>sends it to the display processor (tablet or PI) via serial 
>communication.  The graphics come from a programming language called 
>processing which is basically a front-end to JAVA.  I got this working 
>on a raspberry PI which means a tablet is no longer necessary although 
>it still may be worth spending the extra money for it.  I was concerned
>
>the PI would not handle the load but the latest version has a 1ghz 
>quad-core and proved to be very capable.  Total cost will be around
>$200 
>with a 7-10 inch display.  Cheaper if the display does not have 
>touchscreen functionality but touchscreen will allow doing things like 
>turning on lights, fans, acting as a safety ignition-switch for the 
>motors.  Add wi-fi and you could use your i-phone to operate the sub.
>
>The PI is easier on the pocketbook to lose if water infiltration or 
>condensation gets to the electronics, but a tablet would be more 
>versatile since you could use it for a lot more than just submarine 
>operation.  Then again, for the price of a tablet you could have a
>spare 
>PI and display on board ready to plug in and go.  Anyway, I'll make a 
>final decision on hardware later.  Just a matter of personal choice 
>really...the software will work on anything although things like font 
>selection are sometimes not portable between hardware.
>
>Jon
>
>
>On 7/15/2015 8:19 PM, Steve McQueen via Personal_Submersibles wrote:
>> Jon, very cool. What application creates the new graphics?
>> Steve
>>
>> On Mon, Jul 13, 2015 at 3:09 PM, Jon Wallace via
>Personal_Submersibles 
>> <personal_submersibles at psubs.org 
>> <mailto:personal_submersibles at psubs.org>> wrote:
>>
>>
>>     I am going to move to complete computerized display of sensors
>>     (depth, temp, compass, etc).  My original plan was to feed a bank
>>     of 7-segment LCD displays (see attached image) but the cost of
>>     moving to a tablet is going to be less than double and the
>>     tradeoff of a superior display is worth that extra cost.  If I
>can
>>     find a reasonable priced 10 inch (or so) touchscreen display I
>>     could even use a raspberry-pi instead of a tablet.  I may try
>this
>>     first since I already have a PI.
>>
>>     I've got a prototype for the graphics available at
>>     https://www.youtube.com/watch?v=t9X5iX5pRjM which includes depth,
>>     vertical rate, pitch, roll, and compass heading modeled after an
>>     aircraft multi-function display (MFD).  Note that in the demo
>code
>>     the depth and vrate are not synchronized, nor are the green
>>     up/down indicators associated with VRATE.  I've set a yellow
>alert
>>     at 500 foot depth and a red alarm at 600 feet depth.  I've also
>>     set a yellow alert at 60 feet-per-minute vertical rate and a red
>>     alarm at 90 feet-per-minute vertical rate. Remember Matilda? 
>This
>>     is where her sultry voice will gently reinforce the prospect of
>>     impending doom if the visual alarms are missed (or ignored).
>>
>>     I will be adding cabin/water temperature, humidity, cabin
>>     pressure, O2 and CO2 levels and a clock to the display as soon as
>>     I can figure out what I want them to look like. Might be simple
>>     dials, might be graduated bars...we'll see.
>>
>>     Jon
>>
>
>
>
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>
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