DIY CanBus Gauge

[hjtrbo]

Hi all, looking for suggestions,

I'm hooking into my Links G4 can bus with a home brew module consisting of a PIC micro controller + CAN controller / transceiver that will give me up to 8 x 0-5V analog outputs and a few digital in / outs. Sum total of parts $15. (Programming and development..... lots of hours, but my time is free)

I have tested a VDO oil pressure gauge and I can successfully mimic the operation of the sender via PWM and 1st order filtering to a transistor that provides the current sink for the gauges sense terminal. 

It's not an elegant solution but it works. What I am looking for is a gauge that takes 0-5V and is available in a range of common display types like oil / water temp, oil press etc.

I've been googling around, but nothing is coming up? I have seen dedicated canbus gauges but they are so overpriced and I am not sure if the Link CANBUS operates to a particular automotive standard for its peripherals that I already have hanging off the bus so they may not work.

Any suggestions for 0-5V or something similar?

Edited September 18, 2018 by hjtrbo

[iruvyouskyrine]

I can't offer any help, but please keep this thread updated as this sounds very interesting.

[alexj]

modern "three wire" oil pressure transducers are often 0-5v (0.5 to 4.5). so a guage designed for that could work for you.

iirc on a 32 the factory nissan boost gauge is 0-5v as is the ATTESA front torque gauge.

if you can build the gauge from scratch  then switec low current stepper motors are popular for this sort of thing and can often be driven directly from the mcu (used on GM cars).

I built a can guage to work with my link g4+ a couple of years back and used a 1.5" oled display rather than analogue gauges.

[hjtrbo]

On 9/19/2018 at 3:28 PM, alexj said:

switec low current stepper motor

OK, good advice.

I pulled apart my VDO moving coil gauge. Looks ripe for one of those steppers.

Let me play and i'll update the thread in due course.

 

 

Edited September 20, 2018 by hjtrbo

[Ben C34]

I like where this is going....

[hjtrbo]

OK, good progress.

Data is getting sucked out of the Link and the stepper motor moves. Just got to link the two together in software with a bit of scaling and position tracking, add a bit of glue in the back of the gauge, press on the needle, and she's done! DIY can bus gauge, best $30 (so far) ever spent.

https://au.rs-online.com/web/p/microcontrollers/8802680/

https://www.ebay.com.au/itm/MCP2515-CAN-Bus-Module-TJA1050-Receiver-SPI-Module/302496093646?hash=item466e2c15ce

https://core-electronics.com.au/automotive-gauge-stepper-motor-x27-168.html

[iruvyouskyrine]

Keep us updated with detailed instructions!

[MagicMikeZ32]

I'm confused about what the goal is?

[hjtrbo]

On 10/23/2018 at 11:25 AM, MagicMikeZ32 said:

I'm confused about what the goal is?

to make a can bus gauge

Edited October 27, 2018 by hjtrbo

[Robocop2310]

On 10/27/2018 at 7:53 PM, hjtrbo said:

to make a can bus gauge

And how is this different to any other boost boost gauge?

[hjtrbo]

You don't need extra senders etc on the engine for multiple gauges. Just pull the data out of the ECU. Saves a few hundred dollars and it's fun to learn about something new. 

My boards have arrived from China. Will be soldering them shortly. Will post pics and you can pm me if you want to buy one.

[hjtrbo]

Ok, got the first board soldered up. The canbus module (blue board) then piggy backs onto the board. Still waiting for the mounting standoffs to arrive.

The 4 way terminals are for 2 x stepper motors (2 gauges are supported per board) & 2 x current sinking optically isolated general purpose IO (e.g square drive for RPM or speedo, ECU fault light, shift light etc etc.)

The 2 way terminal is 12V in, and the 3 way terminal is for programming the PIC microchip. There is a jumper to select between run and program modes.

There is a 5V on board regulator with high frequency bypass pass caps for the IC's and large 2 x 470uF decoupling capacitors to help provide a solid power supply to the board. Reverse polarity protection is by the simple inline diode method. 

Still got to get the gauges assembled then hook it all up for a decent test.

 

[alexj]

I'm sure you know already but there are automotive grade regulators available that handle the particular challenges of a car's noisy 12v supply; i used the lm2940.

[hjtrbo]

I didn't know there was such a thing. I come from an industrial machinery background. I'll check them out. Thanks for the tip man :) 

[hotswapster]

Nice work...I've been trying to come up with a similar solution for my bus. I plan on using VDO style senders to an Arduino and then digital potentiometers on the output of the Arduino to make the gauges on the original dash work.

I'm going to give your little project a go though...I've got 3 Empty gauge holes that need filling in my Supra and those can-bus ones are really parking expensive!

Incase you're curious, the arduino project of mine can be found here:

https://github.com/hotswapster/bedford330

It will also have stuff you can use on other vehicles swell.

[hjtrbo]

Progress is going well, but I wanted to update the thread with some learnings that I would employ in hindsight...

• For 12V reg use LM2940 (thanks to alexj for suggestion)
• No need to remove the air core meter and muck around replacing it with a stepper.
  • Consider this method: Instead, cut the resistors off the internal meter terminals, then bring the 4 terminals outside of the gauge body. Then wire them to a CS8190 Precision Air-Core Tach/Speedo Driver with Return to Zero IC.

Hope this helps others on their google knowledge surf.

 

Edited December 11, 2018 by hjtrbo

[hjtrbo]

I redesigned the board to allow for 3 stepper motors, additional IO and changed the colour to match the MCP module off ebay. I used a spare PIC to act as the can bus master to simulate random data. 

This setup is for a Link ECU. I doubt it would take much (if any) modification of the source code to make compatible with Motec. The terminal blocks to the right of the board are provision for switches, shift light, warning light etc etc.

All working now. Car is still getting built so will be a while before they are installed into the dash. 

A short video of them working...

 

[iruvyouskyrine]

Nice! Does this only work with stepper motors or could also work with LCD displays?