G4+ Mazda RX8 CAN Bus

[littlefeck]

The stock ecu sends a signal to bypass the starter solenoid if immobiliser is not happy. You may need to ground this wire. 

[littlefeck]

Do you still have the stock ECU connected?

[Benginetuner]

Ooh, do you happen to know which wire? That'll be the easiest way. 

Yes stock ecu still connected for now so my gauge cluster works, but I want to remove it and use the link to control the dash. I found the can protocols on here from Adam in another thread 

[alexjohn]

HI ADAM  

ask some question about the alternater wiring ?the d1 wiring to alternater light is right?

 

[Adamw]

The charge light is controlled by Virtual aux 2.  In that example map I attached earlier it is set to switch on the light if battery voltage is below 12V. 

[Benginetuner]

Just an update on this thread that I've learned about. The odometer doesn't count up distance covered. Apparently there’s a counter coming from the stock ECU to do the odometer, plus another message the ECU sends out to configure the ABS. The message differs depending on region though (UK, Aus, and USA are all different). 

[Careless]

I'm trying to open the uploaded RX8 CAN example file with both PC Link G4 and G4X, and I get an unable to open error.

Do I need an ECU attached just to view how the CAN functionality of this standalone operates?

[Adamw]

The .pclr file attached earlier is for a G4+ ecu, you will need PC Link G4+.  Get V5.6.7

[cole watson]

Here's an update on some info I've found from a guy who is doing an EV conversion.

he has done a lot of decoding to get his project working. 

His Youtube channel if full of useful info.

He's using Arduino but hopefully we can use his info with our ECU's.

here's some links to his stuff.

GitHub Page: https://github.com/DaveBlackH/MazdaRX8Arduino

Youtube explaination on RX8 BUS: 

 

 

Full Youtube channel: https://www.youtube.com/user/horndoggie999/videos

 

Cheers.

RX8CanBus20-05-2020.xlsx

[666_180sx]

Has anybody tried using this can config on a g4x, I cant get anything to the dash to work. Ive attached a copy of the map.

Jareds RX-8.pclx

[Adamw]

Try this, I have made a few changes to suit the G4X scaling and a few other fixes.

JaredsRX-8 V1.1.pclx

[666_180sx]

Hi adam, Ive tried that updated map with no luck, I cant get anything on the dash to work, I cant even get the wheel speed sensors to read anything in the ecu. Ive triple checked the canbus wiring and even changed it round just to be sure. Not sure what else to try.

[Adamw]

The CAN setup is now close enough that the vast majority of stuff should be working.  It would suggest a wiring issue.  With the ign switch off, what is the resistance measured between CAN H & L?  Unplug the ABS and measure between CAN H/L there.  

[666_180sx]

The resistance between the CAN H and L is 60 ohms at the ecu end and at the ABS plug.

[Adamw]

Ok, that sounds about right.  It is a bit hard to diagnose much further from here, you would really need to connect a scope or sniffer to see what is going on.  

 

[cole watson]

Hey Adam,

I see AiM PDM32 has a odometer counter and can output custom vehicle CAN, do you think this would suffice to get the ODO function working on the factory dash or will this only work with the AiM dashes for the PDM32? 

While we're at it, I have been tossing up between a few PDMs recently, I've got it down to my top 3 so far. Moristech P30, Hardwire PDM25+ or the AiM Pdm32 They all seem to have similar costs. Would you have any recommendations Particularly in my street driven application?

Cheers.

[Adamw]

I dont know specifically what format the RX8 uses for the ODO signal.  I dont come across ODO in CAN streams very often but on the couple of cars I have it is just a counter that increments by 1 every say 10M, then when it gets to 255 it rolls back to 0 and starts again.  So you would need to know exactly what you have to recreate before you could conclude if any of these devices could do it.  

Of the 3 PDM's you mention, they are all pretty capable.  I suggest you play around with each software and try to set up some basic functions to get a feel for them.  I probably have example configs for all of them if you need something to play with. 

Moristech: Be aware it cant use a CAN keypad in standard configuration, it is an extra cost option if you want Keypad integration enabled.  The software has some quirks but it does work ok when you get used to it.  

The Hardwire one I havent had much to do with but I have helped set up a couple remotely.  Again a few quirks in the software that make it a bit frustrating to set up.  For example you have to drill down through about 3 different menus/windows to get to a basic common setting for some functions.

The Aim seems ok.  It was quite buggy when first released but seems to have been improved a lot since then and I havent heard many complaints recently.  Limited to Blink Keypads only, and if you have a keypad then 1 CAN bus is dedicated to the keypad and can do nothing else.   

[Laminar]

For those interested, this guy has figured out the CAN signals needed to increment the RX-8 odometer by writing some code in an Arduino. Not sure if that can easily be translated over to the Link but it's a start.

 

RX8 Project – Part 20, Canbus #5, RX8 Odometer – Chamber of Understanding

[Adamw]

The excel document halfway up this page suggests the ecu just reads the odometer tick from 0x4C0 and sends it out on 0x420, so possibly quite simple if that is correct.  Otherwise, since it is only 1 byte wide I would suspect it will just increment by 1 bit per fixed distance such as 0.1M, then rollover when it gets to 255.  G4X can calculate distance, G4+ cant.  

[Laminar]

On 11/24/2021 at 10:05 PM, Adamw said:

Try this, I have made a few changes to suit the G4X scaling and a few other fixes.

JaredsRX-8 V1.1.pclx 395.87 kB · 36 downloads

Here's what I see in the above file:

R/W	Address (dec)	Address (hex)	Start pos	Data
Read	1200	4B0	0	LF wheel
			16	RF wheel
			32	LR wheel
			48	RR wheel
Write	513	201	0	rpm
			32	wheel speed
	1056	420	0	ECT
			32	Oil light
			40	CE Light
			48	Charge light
	512	200	0	0
			8	0
			16	255
			24	255
			32	0
			40	50
			48	6
			56	129
	514	202	0	137
			8	137
			16	137
			24	25
			32	52
			40	31
			48	200
			56	255

Looking through this CAN setup, I have a couple of questions - based on the Blackhurst spreadsheet, the Chamber of Understanding blogs, and my own CAN sniffing, I don't see any messaging on (dec) addresses 512 and 514 (hex 200 and 202). Based on the linked config, streams 4 and 5 are written to those addresses, but I'm not sure what they're doing. Does anyone have more insight on that? My XtremeX comes in this weekend so I'll be able to test for myself soon.

[Adamw]

3 hours ago, Laminar said:

Looking through this CAN setup, I have a couple of questions - based on the Blackhurst spreadsheet, the Chamber of Understanding blogs, and my own CAN sniffing, I don't see any messaging on (dec) addresses 512 and 514 (hex 200 and 202). Based on the linked config, streams 4 and 5 are written to those addresses, but I'm not sure what they're doing. Does anyone have more insight on that? My XtremeX comes in this weekend so I'll be able to test for myself soon.

Bottom of my post here shows those.  It came from one of the EV forums, some models require these dummy messages to start up the steering pump.  The rally car I done came to me without an OEM ecu so I couldn't sniff anything myself, but it did need these.  

 

[Laminar]

Gotcha. I’m not running the RX8 EPS so I should be able to do without those lines I think. 

[Laminar]

Circling back on this as I'm inching closer to getting things running in the car.

After some more CANbus research, I'm wondering if the G4x can be configured for full instrument panel function.

1. Byte 6 of address 420 is the check engine light. If bit 7 of that byte is high the CEL is on, bit 8 flashes the CEL.

2. On byte 7 of address 420, bit 2 is the low coolant warning, bit 7 is the alternator light, and bit 8 is the oil level warning light (a different byte drives oil the pressure dummy gauge). 

To address a single bit, is it enough to make a parameter that's 1-bit long and put it at its correct starting value? Or do I need to fill the rest of the byte with zeros?

And thinking more about the odometer - the instrument panel expects a counter to increment upwards, one tick per 0.05 miles driven. Can I set up a PWM with a variable frequency scaled to the driven wheel speed, then have a math block count up each time the PWM goes high?

[Adamw]

15 hours ago, Laminar said:

Byte 6 of address 420 is the check engine light. If bit 7 of that byte is high the CEL is on, bit 8 flashes the CEL.

I dont see any need for the bit 8, the ecu will just flash the bit 7 if it wants a flashing lamp. 

 

15 hours ago, Laminar said:

To address a single bit, is it enough to make a parameter that's 1-bit long and put it at its correct starting value? Or do I need to fill the rest of the byte with zeros?

 If you are using a parameter that is only ever going to be 0 or 1 then it is fine to make it 1 bit wide with the correct start pos. 

 

15 hours ago, Laminar said:

And thinking more about the odometer - the instrument panel expects a counter to increment upwards, one tick per 0.05 miles driven. Can I set up a PWM with a variable frequency scaled to the driven wheel speed, then have a math block count up each time the PWM goes high?

According to that excel doc the odo tick comes from the ABS 0x4C0, I assume you just need to retransmit the same value on 0x420.