CwazyWabbit
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Posts posted by CwazyWabbit
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Of course, you'd replace the background of the dial with one that has the letters 'km/h' rather than 'mph', so it would probably have a suitable km/h scale too. The sensor pulses per stepper motor steps / degree of needle deflection would remain the same.
Sure different speeds e.g. 140mph rather than 120mph would need a different calibration factor for the road speed versus needle angle, as RJF was suggesting.
Google tells me that 1 mph = 1.609344 km/h so the 2562ppm might be slightly out (2547.621 pulses)
Kev
Don't forget the total distance traveled recording, that isn't in pulses per angle of stepper motor, that must be a pulses per unit factor.
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4100 is 1004 in hex. Exactly what is in word 08. Word 09 is similar. Maybe one value of pluse per mile for the odo and one for the dial?
Good idea, I've tried a few different values in that word now and anything other than 0x1004 have so far left it refusing to move the needle
all works fine again when it is changed back though -
I'd seriously doubt the VDO unit is storing VIN info, it's a universal part they flog to LR and knowing LR's development style they'll have done the bare minimum to make it work.
I also doubt that *all* of the data is useful or used in this application, very rare that you'd be using exactly the right amount of space on a device, so it'll just be the smallest version that had enough space on it.
As someone else said, the data will probably include a calibration number, MPH/KPH setting, probably a couple of other options (EG illumination always on) - who knows, you could twiddle a bit and make it into a rev counter
Other things I could imagine being stored, either on the quiet or optionally, are store top speed and total up-time / run time.
I'd say there are some mods for Rover though as there is a specific Rover sticker on the PCB.
In this particular case I doubt it's storing the top speed as nothing changed when I ran it from the signal generator at an indicated 120MPH, if it has stored it then James will have some explaining to do to the authorities as to how he managed that speed in his 110
Although it is a very good point and recording uptime would be a very strong possibility even if just to sort out warranty issues between VDO and Land Rover.I might try some 'bit flipping' this evening to see if I can get it to read different speeds while running on a known clock speed.
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These are all the numbers I can find printed on it... oh and a gratuitous mileage shot for James
The date code on the stepper motor seems to agree with the '03 claim for the vehicle...
In image 4 the number written in the same direction as VDO is 0249, you can only see the 49 in the picture.
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My guess would be that pulses per distance and mph/kph are the same thing, i.e it's just pulse per unit or maybe degree..... time to find that now
And top marks for the explanation
Less than 24 hours since we started the project and already we understand the total mileage storage -
Strange
CFBC CFBC CFBC CFBD CFBD CFBD CFBD CFBD = 197671
CFBC CFBC CFBC CFBC CFBD CFBD CFBD CFBD = 197673
I can't get it to 197672 .... I drove around for a while at 120mph till it displayed 197672 but when I disconnected all power it returned as 197673, tried it twice now.
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oops I can't count, under by 13miles
sorry
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I think I may have worked it out.
To program James' Milage in, I reckon you need to program CFBD into the first 8 words of the EEPROM, i.e. instead of the FA64/FA65 that's there at the moment.
If I'm right, I'll tell you how I did it
Kev
p.s. I might be approx 10 miles out, so make the first 16 words look like this:
CFBD CFBD CFBD CFBD CFBC CFBC CFBC CFBC
Tsk, You are under by 3 Miles
Well done! Spill the beans then
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Good stuff!
I know the trip mileage is lost if you remove the permanent 12V supply, so it would make sense that this isn't on the 'permanent' EEPROM. I'm sure the total mileage features decimal points though, and is 'remembered'. Unless that part (the decimal) is stored on volatile memory like the trip mileage and removing the 12V permanent supply would revert your odometer to the whole mile. I know that when you cross 100k the decimal point disappears and you only get whole miles.
PS. It was 197,672 miles that that particular speedo wants to end up as
The fractional miles are lost when the permanent 12v is disconnected. Apparently the fractional mileage is only shown while the total is less than 100 000 as ther isn't enough space afterwards.
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I think you have hit the Nail on the head there Sir! (Mr Freezer)
It also explains something that was puzzling me, when you add a mile on it takes 1 away from one of the 16bit words, when you add the next mile on though it takes 1 away from the next 16bit word. I imagine this is a crude form of wear levelling for counters and would make the flash last longer.
Thanks for that
Now will just need a few more experiments to work it out properly..... then I think we should look at that 3 pin port ...... from what Ralph and Chris have seen from digidash it would seem you only have to open the instrument to remove miles so I'd guess adding miles on can be performed externally via the 3 pin port. Unless Digidash just used a drill on Ralphs!
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I should add it's the first 8 bytes 16 bit words of the flash recording the mileage, the fractions of a mile aren't stored and neither is the trip mileage from what I can see.
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Looks like it counts down from FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF
James your Speedo now reads 1.0 Total
It's not a simple countdown, so I need to work out how to calculate an exact figure... but for now enjoy
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Current mileage is 22953.0 which is not obvious in the hex dump, will clock it on a bit and see what changes when I'm on my lunch break.
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Cheers James
I believe this is the post http://forums.lr4x4.com/index.php?showtopic=14892&view=findpost&p=160740
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.....
I still don't understand how an Earthing fault can cause things to come on though???? Surely if the earths are bad things wont come on. That said even though I have a basic electronics understanding they always present mysteries......
Bad earth allows the dead to rise and they start flicking your switches when you aren't looking...
Or more plausibly electricity always finds the path of least resisitance, so if there is a high resistance on the normal earth point due to corrosion it may find another path via other components causing them to turn on, remember the bunched earths may have poor contact to the body and battery but good contact to each other and as a result when something is turned on that earth bundle may be raised to 12v.
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1 Million read/write cycles and 40 year data retention..... so not as good as a Series 1 Speedo then
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Btw I have the datasheet for the eeprom (small chip) but haven't found any details on the main chip yet...
I best get on with some work now
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Warning NAKED Speedometer Pictures!!!!!
Once you take it apart you can see the only way to open these is to uncrimp the black metal ring ...carefully.
What looks like a seam on the back of the white plastic case is just a flash mark from manufacture.
PS sorry about the picture size, I was trying to leave as much detail in the first one to make it useful and then forgot to resize the second, oops... well maybe people like big chips
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I soldered directly to the legs of the chip using fine wire, theory being I want to make sure it's possible first then we'll work on an easier more accessible method. The chip uses the microwire protocol which is a forerunner to SPI. I used a presto programmer I have from work to do this read but it should be possible to find something cheaper.
Once I manage to power the speedo up I'll clock it on a mile or two and see what changes. Also things like resetting the trip counter may help.
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If you check the reg it is a 2007 .... so maybe it squeezed in
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I'll have a look this weekend and check there are crush tubes in all the holes then I'll be off shopping for some M16's at the least, thanks for your reply lrfarmer
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Mo,
I see where your coming from in the fact it was designed with M16s so in the event of an accident they could blame James for using the wrong parts.
Using that argument you could also argue the use of 5mm plate instead of the original 10mm plate for the part it's bolted to is also a no - no.
I imagine they would have to show it as a contributory cause in an accident as the vehicle is old enough not to require a type approved tow bar.
Caveat to that is I'm not a lawyer and the above is personal opinion .... I would have used like for like if I was doing it.
Looks like I need to have some humble pie I think ..... I met up with James today and he rather politely pointed out that the four bolts holding my tow bar to the rear cross member are M12's and not the M16's that they are supposed to be!
In my defence I didn't fit it, however I will be sorting it out before I tow anything again, I'm also going to consider adding the piece of angle iron to drop the hitch to it's correct height as James also pointed out there is a good chance there are no crush tubes on two of the bolt holes.
previous owners, grrrrr
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Well assuming I have my wiring correct the contents of the memory are as shown in the picture
I really should have worked out how to power the speedo up first to read what the actual mileage is! Doh!
Anyway it's a fairly small bit of memory I read it out by attaching directly to the chip as that three pin port looks to go to the main processor chip, I haven't traced it yet though. Middle of the 3 pins is just GND.
Does anyone know the minimum amount of wires (and which ones) I need to connect to the speedo to get it to come to life? I have James' wiring diagram but unfortunately the pin numbers aren't shown on the speedo so don't know which way to count.
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And mine was done in 2010...so that puts that one out.
However mine was to reduce the reading, as i was getting it put back to 0 to go with the recon engine that had just been fitted! whether that makes any difference or not!
Chris
That might be the difference, James was kind enough to give me permission to open his speedo up so I'll be having a nose about soon, I'll post pictures when she's been laid bare
all works fine again when it is changed back though
Although it is a very good point and recording uptime would be a very strong possibility even if just to sort out warranty issues between VDO and Land Rover.
Less than 24 hours since we started the project and already we understand the total mileage storage 
TD5 Speedo Mileage run up circuit
in Defender Forum (1983 - 2016)
Posted
There looks to be a red light there, but I've never seen one of these in a vehicle
, I'm just doing this for the challenge and because I think people being charged a £100 for changing a few bytes is a bit rough.