DIY Dive Computer

[MaxAlegraD]

Why are you guys not using C??? Microchip/Atmel Controllers??? We are not turning a stepper motor here........

Are any floating point calculations required?? Data bus size, memory requirements???

PADISCUBAPRO has made some very good analysis of the cpu power to run an advanced deco model.

I have to agree with him that some analysis and investigation on this is necessary if the project goals is to have a breakthrough solution.

BX24 was choosen simply because I have a couple around and I wanted to get familiar with the sensors and the waterproof casing of this project. And in fact BX24 is an Atmel AVR... And programming in basic is a lot easier than ASM :10:

As far as I understood models such as VPM-B and RGBM would require a lot of cpu power, 32bit in order to make floating point with double precision and some memory.

I did some research and found the HITACHI SH-4 but it is not yet available for the market.

Even Atmel ATMEGA128 is 8 bit so would be a challange to develop or adapt a model.

Well, I have already ordered a couple of Intersema MS5535 sensors as well as Metallux MSG3500 for air integration.

 

[ShakaZulu]

Hope this device will DL the dive profile via infra red................nice.

 

[DJ69]

I'm thinking more on th basic (not programing language) side of things.
Assuming that CPU power is not the issue,
When you look at programs such as the open source VPM-B code you input the dive profile in advance. This give you the option to asses your profile prior to inputing it and marking the frames as "ascent or descent", "constant depth", "decompression" or "offgassing", while the computer need to decide at what stage it is in an run the coressponding functions.

offgassing is easy, if the depth is '0'
descent is easy. current depth is more then last registered depth.
but how will you deside if an ascent is part of the dive or you need to switch to the decompression functions ?

 

[padiscubapro]

I'm thinking more on th basic (not programing language) side of things.
Assuming that CPU power is not the issue,
When you look at programs such as the open source VPM-B code you input the dive profile in advance. This give you the option to asses your profile prior to inputing it and marking the frames as "ascent or descent", "constant depth", "decompression" or "offgassing", while the computer need to decide at what stage it is in an run the coressponding functions.

offgassing is easy, if the depth is '0'
descent is easy. current depth is more then last registered depth.
but how will you deside if an ascent is part of the dive or you need to switch to the decompression functions ?

The program must constantly do "test ascents" to determine the deco ceiling.. also the program has to constantly sample the depth and see if you are the same, deeper or shallower.. the tissue compartments misy be continually updated.. all three are handled by the Schreiner equation for calculating the current loading or unloading of a segment..

Another think to note.. anyone doing a model for dive computer use should be using the bulhlman 16c coefficients not the more commonly use "b" varient.. "b" is for tables and "c" is for computers.

 

[tfunk]

Learning is certainly one of the goals of this project. Adding new features such as Accelerometers would also be a nice challange. DAN phone numbers can be easely solved with a panic BUTTON we can even put a speaker to create a Divers Alert...

We could also make a some sort of underwater network of divers so if a buddy is consuming too much this information would be passed to his buddy or the boat.

So ideas are endless thats the beauty we can create our own system.

But my original idea was to build a computer that we could really have control over the firmware. I'm sure that most technical divers have found some sort of lack of knowledge over what is happenning with the decompression tables, would like to tweak parameters, etc.

So this project would build a platform (HARDWARE) and a RTDOS (Real Time Diving Operating System) that divers could interface with software to plan and deploy diving profiles.

For most divers this project is really a non-sense since it would require building a computer or acquiring a HOME MADE assembled kit that is non-branded.

But several years ago this same non-sense started several interesting projects and opened the black box that most companies sell to us.

I'm sure someone could start an open-source/hardware project with an FPGA board with a few sensors attached to it. It shouldn't be a problem for an electrical engineer that knows what he's doing.

 

[DJ69]

The program must constantly do "test ascents" to determine the deco ceiling.. also the program has to constantly sample the depth and see if you are the same, deeper or shallower.. the tissue compartments misy be continually updated.. all three are handled by the Schreiner equation for calculating the current loading or unloading of a segment..

At this stage I don't care about the test ascents and deco ceilings. just about the tissue loading/unloading. and it becom more complicatd then just running the Schreiner and Haldane equations. I am going to see a guy who actually know about the subject and he promised to work with me on the project from the phisiological part of the things. (Hell, maybe I will get the RGBM algo' instead of the VPM.....)

 

[Alessio]

With the advent of highly sofisticated microchip technology such as ATMEL AVR, PIC, etc. I was wondering if someone tried to actually build a dive computer ?

All we need a pressure sensor for measuring the depth, pressure sensor for air integration, timer circuit and a case.

The programming could be made in GNU C for Atmel AVR and since most of the chips have internal flash memory and serial ports we can do all sorts of hacking.

The display could be a normal LCD inside the case with 2 or 3 buttons to control the whole gizmo.

Roughly speaking I would estimate the total cost of less than USD 100. Considering the sensors would be the most expensive items.

We can even insert some games for long lasting decompression

Any ideas ? Thoughts ?

Man, about 3 weeks ago I accompanied my girlfriend on her first dive, she was going to take the certification test.

We had a nice weekend at the place where they take the test, I did some diving myself. The guy who runs the outings to the places where we dive has a bus that he uses to takes us to different places to dive. He is an electronic engineer and the owner, operator and master instructor something (what ever the title is) tech diver, blah, blah. He is very cool, has his own shop and knows a lot.

As were coming back home, I was looking at my watch, it is a new casio (pretty cool) with digital compass,, depth gauge, baro, etc. and it reads “triple sensor” then I thought of how “elemental” a watch is this days, compared to what one could make with a commodore 64’s microchip. I never read “triple sensor” on any dive computer (they may have 50, but I never read it on the casing) and I though, I should make a dive computer.

How hard can it be, REALLY, I thought, sensor for the air pressure from the tank, no, 2 sensors then 3 for the water pressure, that makes it 5, then 2 for temperature, hey, seven.

I have been working with computers for a long time, I am director of MIS for the company I work for an even though I am mainly in the management side of the house now, I still play with gadgets and keep in touch with our programming guys in the company. My “right hand” guy in the IT department is an electronic engineer. So I thought, how hard is this project from others I have worked on before? Really? Not that hard.

So I turned around on my seat, in the buss, coming back home with 20 new divers (including my girlfriend) and I started a conversation with the owner of the shop “Hey, why don’t we make a dive computer, imagine, if we get buy a chip, LCD, researchable batteries, some sensors, a nice water proof case, you have experience with scuba equipment, and all that, I can get some people to take care of the hardware and the software, it would rock” ….

Well, it turns out 2 of the guys in the buss were software engineers, in the next 15 minutes, I had 20 guys laughing at me and/or accusing them of being suicidal or trying to murder people with my “dive computer” . There were talks about me breaking laws of Intellectual Property of diving tables, royalties, etc. I thought I was going to jail for a second

So, I let it go and came home and started thinking on how to do it on my own with the help of my team, then I got busy with other things and never got around to working on it.

I empathize with you on the little support you got from some people in this forum, needless to say, I take it for granted that you were at no point asking anybody to break the world record on the first time this computer was to be tested and relying only on this prototype, of course it would be first be tested in the kitchen sink, then bathtub, then swimming pools, and so on, checking it against all kinds of other computers and analog gouges. Of course …

As far as I what I can do for you? You tell me. Software, hardware, share costs, ideas?

I am currently living in Argentina, but usually I live in Miami, but there is fedex.

Good luck and I hope to hear from you, listen to no negative charged comment and pursue original ideas all your life, no matter what anybody says … you are trying to do a good thing here.

Hope to hear from you.

Alessio
Alessio@iNorak.com

 

[FSUDive]

Didn't find this thread until I had already started my own fire over on the computer page. But we have had some intersting discussion on the feasibilty of adapting a pocket pc into a dive computer.

http://www.scubaboard.com/showthread.php?t=117683

 

[Bo Danker]

Didn't find this thread until I had already started my own fire over on the computer page. But we have had some intersting discussion on the feasibilty of adapting a pocket pc into a dive computer.

http://www.scubaboard.com/showthread.php?t=117683

since anyone posted. Any updates? Status reports? hrm...

 

[aabond]

I was going to ask the same question. This thread looks dead, but maybe there's been a little progress.