Feeler: Open Source OBC Firmware

[Joylove]

Good thinking on the GPS. The antenna takes up valuable space and needs a skyview to get a good first fix. All GPS receivers, wired or wireless, will output NMEA standardised GPS data. Some GNS units can do TMC (traffic) too, although I'm not sure if it will work in the US.

Alternatively GPS antenna with an MMCX connectors are only a few pounds from China. They will need a 3V3/5V DC bias for the LNA in the antenna, which the GPS module may or may not provide.

[Mark185]

m2pc, you have convinced me to stop experimenting with AVR processors and order the NXP evaluation board from digi-key. What an incredible jump in capability!

[m2pc]

m2pc, you have convinced me to stop experimenting with AVR processors and order the NXP evaluation board from digi-key. What an incredible jump in capability!

It really is. I haven't found anything with as much power, ease of setup, and wealth of open development tools with any other MCU.

Plus the NXP processors also come in a more powerful version, the LPC1769, which runs at a blazing 120MHz.
I'm going to do some basic programming with the mbed development board, then start laying out the first openOBC board that incorporates the LPC1769.

After doing a lot of SMD soldering at work, I'm tempted to make more of the openOBC board as SMD; this would be a great way to learn SMD soldering, and for the complete kit with board already populated, it won't matter at all using SMD over through-hole.

I received another OBC in the mail yesterday, so I'm back up and running again with my development environment.

[Joylove]

Looks like a nice CPU. Does it allow you to step the code and look for bugs like MPLAB?

[m2pc]

Looks like a nice CPU. Does it allow you to step the code and look for bugs like MPLAB?

According to this: http://mbed.org/handbook/Debugging you can debug in several ways:

1) Use the built-in LEDs on the mbed board to visually indicate program flow
2) Use the standard printf function to write to the USB port on the host for debugging info.

As far as step-debugging, I'm not sure yet whether or not the mbed supports it. Surely the bare LPC176x MCU would support this ability via the JTAG connector, with appropriate debugging software on the PC side.

[Joylove]

Some light reading.

[m2pc]

Update from me: I've been playing around with the mbed some more for personal and at work. I was able to move from a "blinking LEDs" to a SD-card based sound effect machine for a show demo in a couple hours.
Let's put it this way: Data logging with the openOBC is a connector and wires away from becoming reality!

So far I'm incredibly impressed with the whole ecosystem NXP has put together for their MCU's.... much better than any other offering I've encountered thus far.
The biggest asset is the ability to search across all other projects and libraries that others have made; for instance, a fully-functional FAT filesystem for SDCards took me less than 5 minutes to find, add to my project, and get working. AMAZING!

Stay tuned!

[capacitor]

Yes, I recently soldered my first surface mount board at work and it wasn't too bad actually. I used fine tweezers and took my time, and it went well. The daunting part is the pitch of the LPC1768 MCU (0.5mm). The smallest IC I've soldered is your basic SOIC-16 package. Maybe I can through hole most of the design or use easier parts (0603 or 1206) and have the MCU board done outside with a pick-n-place operation.

Surface mount is really easy with a stencil (pololu.com) and a hot plate or skillet. Sparkfun has a writeup on it, but basically the stencil lets you apply solder paste to all the SMD pads quickly/accurately. Place all your chips/components on top of the paste, place the board in the skillet, and when the solder reflows, the chips position themselves pretty much perfectly on their own.

http://www.sparkfun.com/tutorials/58

[m2pc]

Surface mount is really easy with a stencil (pololu.com) and a hot plate or skillet. Sparkfun has a writeup on it, but basically the stencil lets you apply solder paste to all the SMD pads quickly/accurately. Place all your chips/components on top of the paste, place the board in the skillet, and when the solder reflows, the chips position themselves pretty much perfectly on their own.

http://www.sparkfun.com/tutorials/58

Excellent tip, and nice nickname BTW!

In related news, I did an mbed project for work that allowed us to meet a tight deadline with great results:
[ame]http://www.youtube.com/watch?v=0uTETH7Miok[/ame]

[Dricebrug]

And exactly what noise was that?

[johnbimmer]

Yes the bootloader alone will make updates a breeze; I'd much prefer someone being able to connect a USB cable to a notebook PC and reflash the OBC vs. Having them need an expensive programmer.

I settled on the NXP mcu mainly due to high pin count and prebuilt libraries; I'm sure Ardurino is a viable solution as well, for those wishing to use it.

All is not lost on my current design; I spent considerable time measuring components and getting the power supply right; the NXP mcu is a 3.3V part, which simplifies the design considerably, since the GPS and other components are 3.3V also.

Hi, I'm also using NXP but didn't check the components as thoroughly as it seems you did. I haven't yet installed, but it's going to be an easy finish if it's 3.3v, thanks a lot

[Slateman]

Wow, this looks interesting. How much progress have you made on your original goals?

[m2pc]

And exactly what noise was that?

It was a car starting, running, and stopping. The beeping in the beginning was the "key in" warning. My boss recorded the sounds of a coworker's corvette starting.

It sounds a lot better in person.

The point was it was a piece of cake for me to read and play WAV files stored on an SD card.

Wow, this looks interesting. How much progress have you made on your original goals?

Thanks. Well, I have pretty much every signal in and out of the OBC understood and documented; I had boards made using a PIC microcontroller that is apparently the worst ever made (even though it's listed as "mature" and "in production" on the vendor's website).

I'm redoing the board using a more powerful MCU that will allow me to meet all my original goals, and then some. We just may get the German voices integrated after all!

[Dricebrug]

It was a car starting, running, and stopping. The beeping in the beginning was the "key in" warning. My boss recorded the sounds of a coworker's corvette starting.

It sounds a lot better in person.

The point was it was a piece of cake for me to read and play WAV files stored on an SD card.

Oh oh okay. I thought it was a project for your work. Very cool.

Also, I checked out openobc.org but I did not find what I was looking for.

Pinout for the display board, and, have you figured out the vehicle speed sensor?

I have my own little cluster project going on

[Slateman]

Thanks. Well, I have pretty much every signal in and out of the OBC understood and documented; I had boards made using a PIC microcontroller that is apparently the worst ever made (even though it's listed as "mature" and "in production" on the vendor's website).

I'm redoing the board using a more powerful MCU that will allow me to meet all my original goals, and then some. We just may get the German voices integrated after all!

Okay, cool. Sounds like you could have yourself a little side business and make some money

Could you set up the computer to show info like oil temp and boost pressure?

[m2pc]

Oh oh okay. I thought it was a project for your work. Very cool.

Also, I checked out openobc.org but I did not find what I was looking for.

Pinout for the display board, and, have you figured out the vehicle speed sensor?

I have my own little cluster project going on

It is a project for my work; we make automotive test tools, and we purchased the entire dash out of a 1999 Jeep Grand Cherokee to use at trade shows; my boss wanted it to act and sound like a real car, so the mbed came to the rescue!

As for the info on the website, it's a bit stale. I'll try to add some additional info this week on the pinouts and speed sensor input. If you search this thread myself and others have posted info about this.

Speed sensor is an active LOW pulsating signal with x pulses per km (I'll get the exact # for you). This gets you vehicle road speed (how many pulses counted over a specified period of time, converted to mi/h or km/h) and distance travelled (running counter that increments internal mi/km numbers), all in one signal.

[Dricebrug]

Ohh okay, all makes sense now

If you have/can find/ figure out the pulses per KM... that'd be perfect.

I have an 16x2 LCD where the MPG gauge used to be. I was gunna just swap the euro oil temp in there, but figured that was the easy way out. Plus, I wanted some additional functionality.



Got it color matched pretty well and the screen size is *almost* perfect. Should turn out well

[m2pc]

^^^ VERY IMPRESSIVE!!!

Ok, there's 4712 pulses per kilometer. I'd pass this signal through an 74HC14 to square it up a bit (the original OBC does this IIRC) and feed it to a counter pin on your embedded board.

[johnf]

The AVR inputs of an Arduino have ca. 0.3 - 0.4 volts of hysteresis. A two-resistor divider, and possibly an EMC filter capacitor for an edge-triggered input, could do.

[alancop]

I have been following this thread for quite some time, and i was just wondering if you would be able to, in the final iteration, be able to output all of the data over 2 or 3 serial connections, so that i would be able to interface directly to my car computer. Second, if your going to be selling units as retrofits, are we going to have to desolder the black/white connectors that are normally on the back, or are you going to find a distributor?

[m2pc]

I have been following this thread for quite some time, and i was just wondering if you would be able to, in the final iteration, be able to output all of the data over 2 or 3 serial connections, so that i would be able to interface directly to my car computer. Second, if your going to be selling units as retrofits, are we going to have to desolder the black/white connectors that are normally on the back, or are you going to find a distributor?

Yes there's definitely the possibility of exposing all OBC functions over a serial or USB connection; the embedded board I'm looking into using has these plus Ethernet (maybe overkill).

Regarding the connectors, these appear to be a joint effort between BMW and amphenol; desoldering them is quite easy, but we could substitute basic 2x9 box header male connectors instead. The only downside is we lose the keying and locking mechanism BMW designed into the system.

[m2pc]

UPDATE: We now have a source for X1070/X1071 board-level male connectors. Thanks to JoyLove for the UK connection!

[johnf]

Would that be the 967618 connector with the A and B codings? All I can find for sale in small quantities is C.

[m2pc]

Here's the datasheet: http://docs-europe.electrocomponents...6b80ed2388.pdf

It looks like they come in "A" and "B" variants (white/black).

[johnf]

That looks more like it. I may have found a variant that AMP created for someone else.