Berlingo Brake light modification

[Flying John]

Its only odd , I suppose, if you were bought up on analogue electronics (20yrs) and went on to do uP hardware and software (15yrs) , so I can compare both methodologys from considerable experience of both. The few lines of code is akin to the adjustment of the variable resistor on one input of the op amp that would end up driving a relay to set the point at which the brake light would illuminate. This could if you wished be a small rotary control on the dashboard (just like your button).

The component count for the op amp version would be, roughly:-

1 Op amp
4 resistors
1 capacitor
1 driver transistor
1 relay
wire
small piece stripboard

I think something this simple is easily repeatable by other EV'ers who dont have any expertise in electronics as a DIY job.

I accept completely that the adition of a simple switch at the top of the accelerator pedal travel is probably the simplest and least elegant and least functional. As you say the brake light would be on whenever the ignition was on and you are not pressing the pedal - although I think Chris suggested a simple timer type relay that would only keep the brake light on for some user adjusted time interval.

As with everthing in life it is a compromise. I guess at the lowest end it is a simple switch and then in various degrees we have analogue or digital electronics. If you are keen to use a PIC then its always good to have a real project to do to focus ones mind on how a particular micro is best utilised.

I guess thats my 2mA worth...

I think I will try the simple switch first - then the op amp then maybe incorporate it into a micro design that could also monitor other parameters in the drive train - but then the Evlite started out like this....

So how easy is it to get the dash out to get to the back of the eco meter?

[arsharpe]

Hi Simon,

We can debate whether simple is best and component count, etc (and I can add a 2 resistor, 1 transistor, 1 relay option) for ever. But at the end of the day if it is so simple that it does not get done then it is not much use

So good on you Simon.

I would not worry too much about adjusting it in the first version. When you get a new car, you dont worry about the microswitch setting on the brake is set right and as long as it works

Will you be selling your unit and how much ?

Will you be able to tell us where we can get to the meter wire without removing dash ?

Regards,
Rob

[ChrisB]

I love the way we have got three versions of the same thing

Fantastic in my book, love the PIC route ( if only I knew more about them)
Love the Opamp route as its like a midway point I feel, and then you've got the simpletons route of the micro S/W ( dam think that was my idea )

It will interesting to see how they all compare if we get all three operational

ChrisB

[aminorjourney]

Oooh Chris, you just said a dirty word!

(Anacrocomputer HATES PIC chips )

[gooroo]

Okay guys, no need to remove the instrument cluster, the required signal wire is available near the fuse box. If you look up under the dashboard above the throttle pedal you will see 3 round multiplugs with a hexagonal ring used to connect and disconnect the plugs from their sockets. The plugs are coloured GREY, BROWN and BLACK.

The wire you need is in the BLACK plug. I can't give you coloured codes for the wire as Citroen use a numbering system instead of colour codes to identify wires, but on mine it is a GREY wire. The ID number of the wire is 7290.

Looking at the back of the plug (where the wires go into it) there are 5 rows of pins, hold the plug with the row of 3 pins at the top, and the row of 4 pins at the bottom. When I say pins there may or may not be a pin there but there is a position where it should be if one is missing.

So the number of pins (positions) starting top to bottom is 3,5,6,5,4.

Don't get confused by the holes at the edges of the plug that surround the actual pins (positions) these are just part of the moulding and are not pin positions.

So with the row of 3 at the top and the row of 4 at the bottom, you will find 7290 on the far left of the row of 5 second from the bottom.

Something like this

o o o
o o o o o
o o o o o o
x o o o o
o o o o

x = 7290

Hope this comes out well on all fonts, I am using the forum default font.

This pin is the signal from the engine ECU to drive the eco meter. Be warned that loading this wire may cause damage to the ECU, I have so far only monitored this wire using a digital multimeter.

If you still want instructions on removing the instrument cluster I can knock up a guide with some photos, its not to difficult.

Regards, Simon

Okay, just previewed the post, and my attempt at a diagram didn't come quite as I had hoped but I think you will all get the idea

[gooroo]

As for selling the product, I would be happy to sell a completed unit if someone wanted one, I am not looking to make this any sort of commercial venture, not really a large demand. As for cost, no idea yet, but I am not interested in making money from the project, I enjoy doing it

If someone wanted the PCB layout or a ready made board, I would be happy to help out, even if they wanted the source code for the PIC, no problem.

Guess I would only be pi*$ed if someone took it and started selling it for profit, not nice

I am still intent on combining the device with my UltraECO idea as it really would not require any more components, just more code in the PIC. I will start with just the brake light facility though with the UltraECO in mind.

Regards, Simon

[gooroo]

I was looking into some way of notifying the driver when the brake light was on so they could tell when it was operating. On inspecting the instrument cluster I have found one symbol that appears unused by the Berlingo, if I recall it is a Brake Pad Warning light, currently there is no bulb installed in it. The symbol looks a little like this (O) it would be amber coloured.

What are peoples thoughts on using this as an "auto brake active" type indicator? I would probably only have it lit when the auto brake light has turned the brake lights on, not when you put the brakes on manually via the pedal.

I can also use the bulb to indicate a fault by various flashing durations if there was a fault with the auto brake light or indeed if either or both brake lights had blown.

Regards, Simon

[Flying John]

Thats great info Simon - I wonder what sort of load the instrument movement actually presents to the ECU - would be interesting to put a milliammeter in series and measure the magnitude of currents in both traction and regen.

That reminds me I must get round to writing up the brushes purchase and changing. What with Chris and his battery changing we should be able to develop a knowledge base bringing together everyones expereinces.

Chris - do you think we should have a seperate topic entiled PSA knowledgebase ? - or somesuch.

John

[gooroo]

The cluster end arrives at a PCB and does not drive the meter directly, there is also a pot there, presumably for fine tweaking the ECO meter.

Regards, Simon

BTW, on a funny note, if you leave the BLACK connector disconnected and try and drive you Berlingo you will notice that selecting REVERSE makes the Berlingo go FORWARD!

Good job the car in front of me was a fair distance away! lol

Regards, Simon

[anachrocomputer]

Oooh, who said "PIC" just then?? Darn thing only has one register and has to use subterfuge just to get indirect addressing!

But seriously, if you're looking into microcontrollers for EV applications, do look at the Atmel AVR chips. They have 32 8-bit registers and a properly designed RISC instruction set. I have the programing gadget for them, as well as the assembler and C compiler (gcc).

One day, in my copious spare time, I'll get one wired up to the Mini-El as a battery monitor. And a GPS interface. Maybe I'll get it to make toast, too...