Anologue to Can Conversion.

[robsey]

Hi all,

I have a 1994 Vauxhall Car with no can system, however I have fitted a sat-nav / radio / cd player / bluetooth head-unit and graphical display from a CAN configured (late 2004) Vauxhall car.

NOw with the addition of some control modules, I have been able to get all the necessary functions like ignition logic, lighting control, ambient temperature sensing.

The radio is equipped with a "Board Computer function".
Now my problem is that all my sensors provide analogue inputs to the car's ECU, but to monitor these on the display screen, I need to convert these to a suitable CAN system

I know places like ITA, CANverter and FW Murphy make CAN interfaces, but most vehicle systems convert CAN to analogue for running aftermarkey head units.

My question is, how easy is it to go the other way.
To convert my analogue readings from:-
a) Fuel tank level sender - resistance /voltage
b) Injection pulse length - square wave
c) Engine coolant temperature - resistance / voltage
d) Vehicle road speed via ABS sensor pulses - square wave

To a useable CAN signal.

The only way I can think of is to butcher a CAN vehicles engine ECU, but I am quickly running out of space behind my glove box!! :)

Any guesses please ?

[Meat-Head]

THINK you need to arrange these words in the correct order

flogging, horse, a, dead, are, You, mate, to, welcome, kaos, digital.


OFF TOPIC, BUT RELEVENT:

Somebody somewhere (fcuk nows why) had the same problem with an
immo on a VW Gulf4 Turbo engine, so they basically swapped the lot into a VW Shitrocco, they even managed to fit the MK4 Gulf window motors
AND the central locking motors/mechs, speedo the lot. Can't remember what dash it was though.

Such a good job, would would if though it WAS a factory job.

All we did was just a couple of chips on the edge of the door on a reno it was parked next to.

[dafdiagnos]

a can network works with digital signals in millisecond pulses over a 2.5v network, using 120 ohm terminating resistors in ecus to close loop system. you would probably need every ecu, dash set etc off can enabled vehicle. i've seen body builders modules for can to can & can to analogue, but never seen an analogue to can convertor yet

[robsey]

Like I say CANverter and FW Murphy do indeed do analogue to CAN converters, but it is far easier to find CAN to analogue. The FW Murphy is the closest, but doesn't quite tick all the boxes.

Regarding Flogging a dead horse,

Well not really, I managed to make up all my bits for virtually pence...my modules were all 2003 (Vectra 53 plate) items from scrap vehicles.
My radio / CD / mp3 / sat-nav is a 2005 CD70 Navi, and works perfectly...the board computer functions were just an added bonus.

As this forum is not limited to just a Cavalier or a Vectra-C, I just thought there may be a wider spectrum of people with CAN experience.

Yes, I could probably get this to work with a 2003 Vectra-c 1.8 engine ECU.

Any other ideas ?

[dafdiagnos]

if you've already found a manufacturer of analogue to can signal i'd go with this. can signals are not just about the waveform produced, you would need to produce a stable 2.5v can h, 2.5v can l, a 60 ohms circuit using 120 ohm terminating resistors for data transfer, some way to pulse & receive data in millisecond pulses, & a way to decode data. as for myself, i work with can systems on car, commercial, & body builder conversions m8

[russrace]

Converting an analogue signal into a CAN signal is one thing.
Getting your head unit to understand the signal is quiet another.
The software written into your head unit will only respond to the particular CAN identifiers it programmed to monitor or decode, So your first step is to figure out what ID's your headunit works with then design your circuits around that

[robsey]

At the moment, I will just stick to having a bunch of zero's on my Board Computer.

I'm not that conversant with CAN, and so will take the advisement that I shouldn't "flog a dead horse" :)

Many thanks all for your advice and information.