Any interest in developing an open source fuel economy gauge/computer?

[dcb]

I have a confession, I ordered both a serial and a USB, and the little $7 rs232 card for the usb model: http://www.nkcelectronics.com/rs232-...converter.html

I want the $17 one to work because that brings the mpg gauge cost down noticibly and has better reuse potential with older devices without additional costs.

I got the usb one because, well, that's what my blackberry uses. I don't know why I bought the rs232 board though

Re Power Supply voltage, the 7805 is rated for like 35 volts, so it can handle it electrically speaking. Mine didn't feel warm at all at 15 volts after being on for half an hour, but it was only blinking an LED. Dunno, I'd hate to be scared into buying unnecessary components on the one hand, and 7805s are pretty cheap if it does quit.

[s2man]

Yeah, it's rated for 35V. Sorry for the scare. What I read must have pertained to another regulator or 'duino clone.

That $17 Freeduino kit is a great deal. I haven't found a cheaper platform for the our gauge. The tiny Boarduino ($17.5) and Real Bare Bones Board ($15) don't come with serial ports, so folks would still need to buy a programmer. Plus, the Freeduino is the same form factor as the Arduino.

[MetroMPG]

Couple of things...

First..

Originally Posted by dcb

FYI, we have a discussion forum on sourceforge for OpenGauge
https://sourceforge.net/forum/forum.php?forum_id=801345

I exchanged PMs with dcb about sourceforge, and we decided based on the number of EM people who signed up there (4), compared to the number who have contributed to this thread (lots more than 4) that we're going to host the development thread here.

Tomorrow I'm going to add a new forum to EM: "Instrumentation" and start the development thread.

I'll also comb the forums and move all the relevant threads about the MID/SG/vac gauges etc. into the new forum.

dcb asked if I can make it so non-reg'd visitors can post in the OG/MPGuino thread. I can do that, if I make the opengauge/mpguino thread in a subforum of "Instrumentation". Just to clarify, were you asking for that so people who see it at sourceforge can post?

-----

Second: This evening I assembled my freeduino kit. Took me around an hour and a half. Captain slow! I discovered an omission in the assembly instructions at freeduino.org, but it's not rocket science.

For those who are thinking of making their own, I'll post a DIY tomorrow as well.

I'm happy to say it went relatively smoothly, and I just did my "hello world!" equivalent first program and it works! Woo!

I've never done anything like this before, so it's a good sign for others who are wondering if they're up to the task.

[dcb]

Originally Posted by MetroMPG

dcb asked if I can make it so non-reg'd visitors can post in the OG/MPGuino thread.

I ask because it was a sourceforge option, I cannot speak much to the wisdom of allowing completely anonymous posters, but there are some obvious concerns:

On the one hand some folks will have trouble registering here and won't be able to post, likely when they are trying to get help with something.

On the other hand the quality of the posts may suffer when allowing completely anonymous users to post.

P.S. Good job getting the freeduino together. It is quite a satisfying thing to get that little computer to do what you tell it, no? I showed it off to several visitors this weekend and they were duely impressed, also got it to wiggle a servo motor which was kind of cool.

I do think, getting it to do more than one thing at a time WELL is going to be an interesting challenge.

P.P.S. re communication, the serial version just uses a couple transisters to simulate rs232, it does not do any buffering or anything, so I think the atmega should only transmit (like a logging device), and not do any handshaking with the palm/laptop. Once a second it sends out 3 bytes for number of high cycles (24 bit unsigned integer), 3 bytes for total number of cycles(24 bit unsigned integer), and 2 bytes for vss tics(16 bit unsigned integer), and the palm/laptop, which probably has decent rs232 support, will have to collect the info at least once a second.

If the palm/laptop has to collect the data once a second but postpone the display update for 4 seconds or something, because the display update takes more than a second and there is no thread prioritization, then that's the way it has to be.

P.P.P.S. The obdgauge palm software seems to have a fatal flaw that I'm not keen on fixing at the moment, I will try and model the palm gui after the laptop version, though I will first try and get the laptop version to speak the once a second 8 byte receive only protocol described above. It's a lot easier for me to work on java than palm, and anyone working on the signal processing might want to debug the atmega without buying additional hardware.

[dcb]

We may need another value for the total number of injector pulses (RPM would be nice).

Here is http://planetchampions.org/diympggauge/i1.wav parsed into about 26 once a second data values (has an injector on one channel and a vss on the other). It should be possible to play inj.wav into the freeduino signal processor and come up with similiar numbers on the serial port.

//tCycles and injHIMS in microseconds, injCount can help with RPM, vssCount for speed/distance
unsigned long tCycles[]={1000000,1500000,1000000,1000000,1000000,1500000,1000000,1000000,1000000,1000000,1500000,1000000,1000000,1000000,1000000,1500000,1000000,1000000,1000000,1000000,1500000,1000000,1000000,1000000,1500000,684965};
unsigned long injHIms[]={69002,168956,115736,105510,201632,188231,164693,165873,176190,113628,212222,86780,48253,39501,38049,55941,37006,37142,39433,62879,107392,72993,89047,92562,115170,47891};
unsigned int injCount[]={37,55,42,42,43,71,50,42,46,68,37,38,39,38,55,36,34,33,32,47,32,31,32,32,49,22};
unsigned int vssCount[]={0,8,11,14,26,20,22,25,38,28,28,29,28,42,26,26,25,24,35,24,23,24,24,36,17};

I will attempt to add these to a dummy freeduino program that spits these 4 values out the serial port once a second, as soon as I figure out timer interrupts. It may be that tCycles isn't necessary, but the samples from the soundcard were not so predictable in size.

[larrydag]

Originally Posted by MetroMPG

Couple of things...

Second: This evening I assembled my freeduino kit. Took me around an hour and a half. Captain slow! I discovered an omission in the assembly instructions at freeduino.org, but it's not rocket science.

For those who are thinking of making their own, I'll post a DIY tomorrow as well.

I'm happy to say it went relatively smoothly, and I just did my "hello world!" equivalent first program and it works! Woo!

I've never done anything like this before, so it's a good sign for others who are wondering if they're up to the task.

Well I should go ahead and get mine then! Thanks for the update. You got the USB version, correct?

[MetroMPG]

Confirm with dcb, but I think you want to get the serial *duino if you want to pursue Palm connectivity.

(I had already ordered the USB one before that project track developed).

Also, I won't be posting that DIY today - too busy - but I will get it up there in the next few.

[dcb]

re: serial v/s usb.

If you have a serial port, you can save yourself $7 and get the serial version. I cannot guarantee it will work with the palm yet, but certainly it will work with the standalone MPGUino, and why make end users pay for a usb port that they will only use once to program it?

Of course if yoru pc/laptops are legacy free, you might want to get the usb version.

If you want to prepare for all support contingencies, then get one of each and possibly the rs232 card

[larrydag]

Originally Posted by dcb

re: serial v/s usb.

If you have a serial port, you can save yourself $7 and get the serial version. I cannot guarantee it will work with the palm yet, but certainly it will work with the standalone MPGUino, and why make end users pay for a usb port that they will only use once to program it?

Of course if yoru pc/laptops are legacy free, you might want to get the usb version.

If you want to prepare for all support contingencies, then get one of each and possibly the rs232 card

I got one of each. I will hope to do some hardware testing by the end of the weekend.

[Whoops]

Ok, I ordered a serial version of freedunio. Has their been any choice or suggestions for a stand alone display?

On the 7805 regulator, the heat issue would only come up from having to much of a current load on it. I really doubt that running what is on a freedunio is going to cause it any consternation.

On the question of opening this to anyone to edit or add to a thread, I wouldn't do it. If someone doesn't have enough interest to register, I wouldn't give them a way to just arbitrarily dump stuff. It's not a tremendous amount of protection, but it's better than not.