arduino & touchslide

[Jon Wildsmith]

On my 100 I picked up the speed sensor pulse at the engine ECU but it's the speed sensor on the rear output housing of the transfer box on 80's and 100's (pretty sure 120's are different but Gary knows the details for that). For an 80 you should search the net for how to install an electronic speedo corrector as that taps into the same signal but you should be able to find it behind the dash somewhere at one of the ECU's. Mine is already corrected by a different gadget I built. It's possible I'll build a corrected output into this and remove the existing correction device but it's not a high priority for me.

There are other things the trip meters do BTW. For the A & B trips it calculates average speed, might be useful for anywhere with average speed fines For the P & L trips it maintains totals as well as the current trip values and calculates l/100km or mpg from the totals.

 

[Rob]

How do you plan to do the fuel consumption calcs? will you input how much fuel you filled up manually or can you tap into the petrol/LPG ECUs to get this data? Seems like the first one is easier to do and will be compatible with more vehicles

 

[Jon Wildsmith]

When you zero the P or L trip values you can also enter the amount of fuel added in which case the average and last consumption can be calculated for you Nothing you couldn't do manually but it saves the trouble That description is a little ahead of what the UI actually presents at the moment but the back end is all there just waiting to be exposed when I have another few hours free.

 

[Justin_Elliott]

Jon - excellent idea & progress made... Really impressed....

Any objections to a wannabe following your work? If you're willing to share snippets as you move through the project?

 

[Jon Wildsmith]

I'm posting so other people can have a go so if there's something you want to know, ask

 

[Justin_Elliott]

I'll get ordering then - once I've had a play I'll be in touch - sounds interesting!

 

[Richard Jackaman]

Jon

Got the information about connection for the speedo pulses from the web, need to have a look at the loom when I get a chance to try to identify the connector in situ.

Are you polling the pulses or using an interrupt on a digital input on the Arduino?

I did have a thought about using a 1-wire counter (DS2423) to do this but Maxim have stopped making them and availability is difficult.

Cheers

 

[Jon Wildsmith]

Re: arduino & touchslide

Using an interrupt, the mega has quite a few which is handy for other things as well.

 

[BRE Fabrications LTD]

Whoa, haven't felt this confused since high school chemistry...

:confusion-seeingstars: :confusion-scratchheadyellow: :confusion-scratchheadblue: :confusion-questionmarks:

 

[Jon Wildsmith]

That's ok you don't need to know how it does it Ryan, just connect the right wires together when the time comes I'm pretty sure ih8mud has writeups on the installation of speedo correctors to petrol 80 series which will cover the wire you need access to

 

[Gary Stockton]

Hey Doctor - I've been cogitating on this gizmo of yours, in between working out whether reactance goes up or down when either inductance or capacitance goes up or down, and what the characteristics of a Zener diode look like - goddam radio electronics!!!

So - do you think the screen can multi-task? I.e. Can you have your info display up most of the time, then flip over to real-time navigation/mapping from an on-board pc and gps, and email/browsing or similar when stopped - off the same pc? So I guess it would need two input ports and a switch facility, or an external switch of some form?

I don't think I have the space to run 2 screens ...

 

[Jon Wildsmith]

Maybe the scale of this hasn't come across in the pics but it's only a 3" screen and it's driven by a dedicated microprocessor board so a PC is only involved to program the device. It could throw all the data at a PC and I could write a PC UI but being a relatively simple, stand alone & reliable device is top of my requirements list so I won't be going down that road

 

[Gary Stockton]

Ok - got it. Hadn't realised it was that small - even more impressive then, and can probably hang off the 'A' pillar in a custom moulding ...

Cheers

 

[Jon Wildsmith]

At the moment I plan to put it in a small mud pod (painted grey) on top of the middle of the dash and there'll be space on the pod for 2 or 3 carling switches as well. There are all sorts of box's that could be used instead and before I commit to the pod I'll sit in the truck eyeing up the options a few more times but whatever I choose doesn't limit what someone else might choose

Just taken delivery of another set of parts so I can get on with installing one in the truck for field testing but not have to keep taking it in and out for developement to continue.

I had planned to use strip board for the few extra components needed but I noticed these so I got a couple of those as well and unless there's a problem with them intend to mount the extra components on one of those.

 

[Richard Jackaman]

Gary, I'll bring one along on Saturday and you can see for yourself the size of the screen.

Jon, Farnell also stock arduino bits and pieces and if you can get a trade account the do free next day shipping.

Cheers

 

[Jon Wildsmith]

I think when I looked on Farnell they didn't have stock of what I wanted but cool components do free delivery as well so I don't think there's much if anything in the cost.

If you or anyone else who has bought bits is ready to start playing then I'll start posting more information about how I've got it set up and the hex files of the current state of play for you to upload

 

[Justin_Elliott]

Definitely interested to see more - if you can find the time to post it all....

Although I'm still playing catch up - so I'm not in any rush.

 

[Richard Jackaman]

If you or anyone else who has bought bits is ready to start playing then I'll start posting more information about how I've got it set up and the hex files of the current state of play for you to upload

Definitely interested in more details. Currently got lots of bits sitting on my desk but still in the "testing what it can do" stage. More accurately "testing what I can make it do" with the limit being my ability to grasp some things. Not really done much with the slide yet. Drawn some boxes and played about with displaying some text but that's about it so far.

My current plan is to install the arduino in a case somewhere under the dash to do all the sensor reading etc and to use a cat 5 cable to connect to the screen which will be installed in a separate case somewhere visible on the dash. Arduino will be powered permanently off a live feed but will sense when the ignition is off so can store any trip information into it's flash memory in case of power disconnection.

Any help and advice would be great.

Cheers

 

[Jon Wildsmith]

I'm using a slightly hacked version of the Arduino IDE, having experimented with Eclipse and the AVR IDE and found them more trouble than they're worth for this. The Arduino and Slide are both available on the Tools->Board menu instead of having to run a seperate version for the slide which just involved a bit of copy and paste in the config files and hacking the hardware serial code a bit. All the on-line references to Arduino to slide serial communication seem to want to use software bit banging but TBH that's not very reliable so I'm using hardware serial so on both the Arduino and Slide, Serial1 is the other board. The slide pins that were connected to the Arduino pins 2&3 I have conected to Arduino pins 18&19 (Serial1) and running at 115200 is rock solid as you'd expect (don't forget to cross them over so TX goes to RX).

On the slide, writing to the LCD is pretty slow, as far as I can tell each pixel operation is fairly involved sequence of IO operations on the mega chip to tell the LCD chip to change or read that pixel, no memory mapped I/O or direct LCD RAM access. There's probably clever stuff to be done with reprogramming that, but that would be a distraction too far.

On the Arduino, the ADC's are easy to access, seem reasonably stable and I'm just using a resistor voltage divider to scale the '12v' signals down.

More to follow ...

 

[Jon Wildsmith]

I should point out my skill is software systems design and engineering BTW, not graphics or electronics but I can scrape by on those

I have power for this device derrived from the two battery voltage sense inputs via a diode on each, so that if either battery has power the device will be powered. At 14.4v the regulator on the arduino gets a bit hot as warned about on the net so I'll be dealing with that soon. I'm seeing a current draw of up to 110mA with a busy display and 70mA with the display off. I don't really want a permanent 70mA power draw so my plan for power management (little of it implemented yet) is to have a sense line for either aux or ign (via a diode for isolation and pull down resistor) and have the device fully awake when that is high. When that line (I'll use an interrupt enabled pin) is low I'll use a timer to put the code into power saving mode. In power saving mode I'll put the display, serial ports and as much of the arduino as possible to sleep while the battery logic reports linking is viable. Once linking is not viable (takes a while for battery voltages to fall after the engine has been running) I'll put the arduino to sleep properly. For this state I will be adding an external 32k crystal to run an RTC and wake the arduino up every second or so and have it check for battery voltages low enough to trigger a warning or high enough to enable linking (like connecting a solar panel or other external charge source). Turning the key to Aux or Ign (depending how it's connected) would wake it up again due to using the interrupt enabled pin for this.