SMD needs a lot of equipment, its to expensive for only some projects. Your design thinkings i couldn't see on the photo, so i give you my impressions what i recognise on the type of the parts. But one point remains for me not enaugh considered: When IVECO documention says 15,7V is Max, it means only at all electric parts has to work until this level. But there are events defined when even higher voltages can occur: alternator disconnect, batterie disconnect, Jump Start with 24V, power spikes from heavy loads, ..... For this every commercial control units hase to use protection cicurits at every pin for Voltages level up to 5000V for electrostatic discharge and 240V AC/DC for some minutes. And Powerlines has to be protected for 28V DC continously. There are a lot of specs about this. So if you look at your original AFAM-Board you see at every pin this protection resistors and capacitors for this reason. In the real vehicle bord net all control units are connected at the powerlines and give protection functionality also for other units (when near enaugh). In any way, I would suggest you to add one varistor at powerline for security.
With vibrations i don't aspect that the arduinoboard jumps out, the problem is possible shorttime interruption (milliseconds) of the pin-connection itself at vibration. The reliability of this connectiontyp generally isn't accepted in automotive industry. But this part you cannot change, and with this less units you probably never find out a problem.
I am quite happy with the performance I have had it running in my truck for many months now from sea-level to over 4800m in dry arid derset to hot and humid jungle. Don has also been operating his quite successfully in Australia too. Interestingly Don's original Iveco AFAM has just failed while he tested it, possible due to a static issue while it was being handled - we have not had an issue with static on the Arduino Due. I guess Iveco didn't do a very good job in meeting the 5000V spec! As for 240V AC/DC why? Are you going to plug your ECU into a mains feed? Given the track spacing on the original AFAM I would be surprised if it could meet that spec. And as for the case of jump starting with 24V, I would be more worried about the 12V battery exploding and showering you in acid - sounds like a Darwin award winner to me.
I think you need to keep things into perspective here, a new AFAM from Iveco is about 1700 Euros and operationally is junk. Don is selling this replacement for under 300 euros, if the Arduino was to be damaged by a static discharge or 24V jump starting, a new Arduino Due would cost you under 40 Euros to replace. I worked in the aviation industry and am well aware of how indestructible you can make electronics but there are costs associated with it. I really don't think anymore protection is required. However, if there is demand I could add a lot of extra circuitry to make it as tough as you like.
I should also say that genuine Arduino Due are supplied by the manufacturer in small cardboard boxes with no anti-static protection - they are clearly quite resilient devices.
more often you handle a ECU it gets more in danger of electrostatic discharge - i can't estimate the design quality of AFAM- circuitry. Yes, for industrial quantities the specs even regards the possibility on contact with main supplys, more possible in distribution for spare parts as in the car manufactoring process. I had the case that an simple Barcode Scanner, only put down for resting on a plastic surface, has issued 15kV discharge with damaging internal protection circuitry of an input OP-AMP IC in an Control Unit at the production line about every 5000 units (but it had open housing at this production step). I have no fear about environment conditions for your electronic - this alu case gives good mechanical protection even against batterie-acid. The rare cases when the MOSFETs switches the Diff-locks produce no heat all, and there is enaugh air inside for ventilating the working arduino. I talk not about prices (IVECO let you pay again developement costs on spare parts), i think only on the trouble when the box fails: it comes back to you personally. A varistor costs only some cents and can be simply added. It was only a suggestion from my side with my experience.
Great job, that, and I believe everyone knows the scope you are doing this at. Even if it is sold by Don in a slightly more commercial manner, as long as the story behind it is shared and known I don't think you need to make it automotive-grade. Even if the odd box fails people will accept this and still be happy to have a superior capability than the original (That doesn't mean Erichs suggestions are not good).
Just another thought to consider - how about adding a few simple backup switches (or buttons) to the design, parallel to the uC, that allow to manually switch the locks as a measure of last resort, overriding everything else? For example if the electronics or speed sensors fail in a very unpleasant situation such as a ford, where you have to react swiftly? You would have to make sure this is well understood by the user and not activated accidentally or considered normal operation though.
I wasn't going to mention this until the design is a little closer to market but I have designed a serial interface into the replacement AFAM module. I have also made use of all the unused 'pin' locations in the existing AFAM plug for additional functionality. Therefore, if you want to add a varister between the VIN and ground you could just connect it to pin 4 and 8 of the AFAM plug.
I have designed an expansion board that will connect to these 'extra' pins and it provides 10 analogue inputs to the AFAM that can be used for temperature sensors, pressure sensors, voltage or current monitoring. All the data is streamed out of the AFAM on a serial port that can be connected to a display on the dash board. This is how I have been monitoring the system temperature and voltage in the prototype, you can see some of the additional data on the bottom two lines of the LCD in this video:
All this functionality is embedded in the AFAM's that Don is shipping now. This means customers will be able to add this to there AFAM at a later date when we can make the expansion board available, no reprogramming of the AFAM will be required.
I have also added serial data the other way so the remote display can control the function of the AFAM, mainly just the PTO controls and lights for now as I thought not many people have these fitted but could use the existing wiring to control other devices if required. It would be very easy to add full control of the AFAM from a touch screen so you could use it as a backup for the mechanical switches or to replace them completely if you wanted to go to a 'glass cockpit' design! I am investigating suitable touch screens and software to make it all look good and am also looking to integrate a reversing camera into the system so you can have one touch screen in place of an existing reversing camera screen that will do so much more.
Here is a screen shot of a quick mock up of what could be on the display, I have gone for older retro looking gauges but I will probably design a few pages so the user can choose what they like, modern digital, old analogue your choice, I could even do the modern avionics option of a blank screen until something gets near a limit and then it is displayed - the options are endless....
As the project develops I will update you. The real problem I am having is getting parts to me in South America, it is really slowing down the development...
Marcus
Zuletzt bearbeitet von Marcus Tuck; 01/08/201713:49.
Having read the above thread Don decided to test the new AFAM to see how it would handle an over-voltage event. I believe the automotive tests are for an over-voltage for a few milliseconds, Don ran the AFAM at 29.8 volts (the maximum voltage for his power supply) for a couple of hours! The only failures, not surprisingly, were the LEDs in the test rig. These LEDs are the same as in the truck, the AFAM remained fully functional.
