CAN Coms on a Trubokitty MS3x
08-21-2020, 10:52 AM
#1
Junior Member
Thread Starter
Join Date: Mar 2018
Location: Montevallo, AL
Posts: 100
Total Cats: 10
CAN Coms on a Trubokitty MS3x
I've been up and running on a MS3x built with Brains instructions on trubokitty. Recently my Innovate MTXL wideband died and I decided to switch to an AEM X series wideband. (30-0300).
I've wired it in and it has power and is reading correctly but it will not communicate with my MS through can.
I've wired CAN H and CAN L to pin 3 and 4 on the mainboard connector.
All my settings are adjusted according to these posts https://www.miataturbo.net/megasquir...3-basic-99838/ (post #8) and https://www.miataturbo.net/megasquir...9/#post1465718 (post #9 and 10) However both these guys are running MSpros or rev built MS.
I noticed on the MS3X hardware manual that the optional connections must be made internally. The board schematic says JS6 is CAN H and JS8 is CAN L so I assume there needs to be a jumper wire installed between those and their respective pins on the connector but I wanted to make sure. I'm relatively new to this stuff and wanted to verify before I did something dumb. Here is an excerpt from the Megamanual detailing the jumpers.
"If you will be using CAN communication between boards (MS-II and GPIO, for example), you should also jumper JS6 to SPR1/CANH and JS8 to SPR2/CANL
So for MS-II implementation, the following connector signal jumpers are suggested:
CPU Connector Description
JS0 IAC1A Stepper motor signal 1A
JS1 IAC1B Stepper motor signal 1B
JS2 IAC2A Stepper motor signal 2A
JS3 IAC2B Stepper motor signal 2B
JS10 IGN or IGBTIN (w/ IGBTOUT->IGN) Ignition output
JS6 SPR1/CANH CAN High
JS8 SPR2/CANL CAN Low
(Note: If you are using a PWM style idle controller instead of a stepper IAC, see step #62.)"
If I am understanding correctly I need to open up the case and take a wire from JS6 to pin 3 and one from JS8 to pin 4 on the mainboard connector and the CAN connections should be made. Is there any other wiring or component install that needs to go along with that?
My only concern with this set of instructions is this is for the standard V3.0 board for use with a MS-II based system and I don't have a deep enough understanding of how the internals of the main board and the 3x board communicate.
I've wired it in and it has power and is reading correctly but it will not communicate with my MS through can.
I've wired CAN H and CAN L to pin 3 and 4 on the mainboard connector.
All my settings are adjusted according to these posts https://www.miataturbo.net/megasquir...3-basic-99838/ (post #8) and https://www.miataturbo.net/megasquir...9/#post1465718 (post #9 and 10) However both these guys are running MSpros or rev built MS.
I noticed on the MS3X hardware manual that the optional connections must be made internally. The board schematic says JS6 is CAN H and JS8 is CAN L so I assume there needs to be a jumper wire installed between those and their respective pins on the connector but I wanted to make sure. I'm relatively new to this stuff and wanted to verify before I did something dumb. Here is an excerpt from the Megamanual detailing the jumpers.
"If you will be using CAN communication between boards (MS-II and GPIO, for example), you should also jumper JS6 to SPR1/CANH and JS8 to SPR2/CANL
So for MS-II implementation, the following connector signal jumpers are suggested:
CPU Connector Description
JS0 IAC1A Stepper motor signal 1A
JS1 IAC1B Stepper motor signal 1B
JS2 IAC2A Stepper motor signal 2A
JS3 IAC2B Stepper motor signal 2B
JS10 IGN or IGBTIN (w/ IGBTOUT->IGN) Ignition output
JS6 SPR1/CANH CAN High
JS8 SPR2/CANL CAN Low
(Note: If you are using a PWM style idle controller instead of a stepper IAC, see step #62.)"
If I am understanding correctly I need to open up the case and take a wire from JS6 to pin 3 and one from JS8 to pin 4 on the mainboard connector and the CAN connections should be made. Is there any other wiring or component install that needs to go along with that?
My only concern with this set of instructions is this is for the standard V3.0 board for use with a MS-II based system and I don't have a deep enough understanding of how the internals of the main board and the 3x board communicate.
Reply
0
0
08-21-2020, 12:36 PM
#2
Why are you confused? Megasquirt has great documentation. As per page 38 in the hardware reference manual, you need to run jumpers as shown in section ERROR FILE NOT FOUND.
http://www.msextra.com/doc/pdf/MS3XV30_Hardware-1.3.pdf
Twist the wires, 1 per inch. Canbus is differential signal, needs to be in close proximity to each other to work best.
Otherwise I've read that AEM uses 29bit identifiers, and not in a way that megasquirt can handle since it uses a proprietary 29bit header. You pretty much break all megasquirt specific canbus comms, except maybe the 11bit broadcasts?
Think AEM defaults to 1Meg too, while megasquirt starts at 500K and pretty much breaks everything but that at 1Meg.
In other words, I wouldn't want to set it up for CAN by itself, but only because I use megasquirt canbus for a lot of other things.
http://www.msextra.com/doc/pdf/MS3XV30_Hardware-1.3.pdf
Twist the wires, 1 per inch. Canbus is differential signal, needs to be in close proximity to each other to work best.
Otherwise I've read that AEM uses 29bit identifiers, and not in a way that megasquirt can handle since it uses a proprietary 29bit header. You pretty much break all megasquirt specific canbus comms, except maybe the 11bit broadcasts?
Think AEM defaults to 1Meg too, while megasquirt starts at 500K and pretty much breaks everything but that at 1Meg.
In other words, I wouldn't want to set it up for CAN by itself, but only because I use megasquirt canbus for a lot of other things.
Reply
0
0
08-21-2020, 01:39 PM
#3
Junior Member
Thread Starter
Join Date: Mar 2018
Location: Montevallo, AL
Posts: 100
Total Cats: 10
Yep to get the AEM x-series stuff to work over can you have to disable all other can comms. They added AEMnet compatibility with firmware update 1.5. I have no problem with that as I have no other hardware that communicates through can and would rather have an easy reliable O2 signal for the time being.
As for getting the jumpers installed, I was aware that those are the jumpers that needed to be installed(there's even a lovely picture of them on page 215 that I found this morning haha). My concern was really just messing with any of Brains other stuff he had going on in his build.
Anyway, I installed both jumpers and everything works. So if anyone is building a Trubokitty MS3x and wants to use any can device remember to jump JS6 to SPR1 and JS8 to SPR2 (preferably before you install the MS3x daughterboard) and can will work as intended.
Also the can wires in the O2 sensor harness were twisted and they connected right into the options harness so I think I'm good there. I am still going to have to see if I need to terminate the signal with a resistor. If there is tons of noise in the signal I may consider it although I think most people have been fine without one.
As for getting the jumpers installed, I was aware that those are the jumpers that needed to be installed(there's even a lovely picture of them on page 215 that I found this morning haha). My concern was really just messing with any of Brains other stuff he had going on in his build.
Anyway, I installed both jumpers and everything works. So if anyone is building a Trubokitty MS3x and wants to use any can device remember to jump JS6 to SPR1 and JS8 to SPR2 (preferably before you install the MS3x daughterboard) and can will work as intended.
Also the can wires in the O2 sensor harness were twisted and they connected right into the options harness so I think I'm good there. I am still going to have to see if I need to terminate the signal with a resistor. If there is tons of noise in the signal I may consider it although I think most people have been fine without one.
Reply
0
0
08-21-2020, 01:49 PM
#4
Can network should only have two resistors, the megasquirt has one that can't be disabled and if all you have otherwise is the gauge then you should have a 120ohm resistor across the can lines. The gauge might have a jumper or software config for it, instead of having to hardwire it.
It might work without it, but if you are after reliable signal you should probably make sure you have proper termination. Canbus transceivers have a little leeway on the signal they will lock onto but it's not a good idea to rely on that.
It might work without it, but if you are after reliable signal you should probably make sure you have proper termination. Canbus transceivers have a little leeway on the signal they will lock onto but it's not a good idea to rely on that.
Reply
1
1
08-21-2020, 02:04 PM
#5
Junior Member
Thread Starter
Join Date: Mar 2018
Location: Montevallo, AL
Posts: 100
Total Cats: 10
Yep after reading a bit more the gauge has a software configurable resistor and its factory calibration is 120ohm I believe. In just starting the car the gauge is 100% accurate in TS and is quite stable.
I'm just a bit gun-shy with can systems because I'm about to embark on converting my brothers NC to a Haltech ECU and I thought for a second I was going to have problems with the can system that basically runs the car. That was a non issue to begin with but I learned a ton in the process.
With this I was just overthinking a simple install. Thanks for taking the time to help me out.
I'm just a bit gun-shy with can systems because I'm about to embark on converting my brothers NC to a Haltech ECU and I thought for a second I was going to have problems with the can system that basically runs the car. That was a non issue to begin with but I learned a ton in the process.
With this I was just overthinking a simple install. Thanks for taking the time to help me out.
Reply
0
0
Thread
Thread Starter
Forum
Replies
Last Post
