CAN module - SN65HVD230

[AndreyB]

Based on SN65HVD230
Current status: rev 0.1 is totally functional!
Ordered rev 0.2 with silkscreen improvements


can_board.zip
Schematic.pdf
SVN repository

ibom available at https://rusefi.com/docs/ibom/

[Sergey89]

This is schematic from a Russian ECU (not russian )

can.png (15.94 KiB) Viewed 14830 times

[kb1gtt]

I had once done this on an IO board. See page 2 found here http://daecu.googlecode.com/svn/Hardware/trunk/KICAD_Project_TRK-MPC5634_P3-P4-ETPU_IO_proto/TRK-MPC5634_ETPU_IO-board-sch_RA.pdf Look bottom right, for the TJA1051 chip. It wouldn't hurt to add the RF choke and ESD noted in the schematic above.

[blundar]

It might also be nice to have a bus termination jumper. 120ohm termination is expected at the end of CANbus nodes. I use RC1206FR-07120RL

I've wondered about doing this with a FET, either using solely a FET with RDSon close to 120ohms or using a FET with extremely low RDSon coupled with a fixed resistor in order to have software-selectable termination, but I haven't had a chance to experiment with this yet and determine how effective it is.

It is also good form to put two 50pf decoupling caps. I used 51pf because I had them around. This helps remove some high frequency noise components and is a recommended practice from many of the CAN transceiver datasheets. One decoupling cap from CAN- and one from CAN+ to ground.

[Art_ELectro]

...bus termination jumper. 120ohm...

Added.

[AndreyB]

What is the role of the jumper? Why do we need it on the line terminator?

[abecedarian]

What is the role of the jumper? Why do we need it on the line terminator?

It's required per CAN specifications that end-points are terminated.
Mid-span branches aren't required to be terminated, as such, but long branches should be terminated as well.

[jedediah_frey]

What is the role of the jumper? Why do we need it on the line terminator?

CAN spec requires it. The jumper allows you either enable it or disable it.

For example if you wanted to add another ECM on another CAN network on you'd need a terminator

[abecedarian]

The termination is only required at the 'endpoints' of the system; prevents reflections from travelling backwards through the wiring.

So, say:

Code: Select all

CAN TPS > ====== MCU ====== < Dashboard

Terminations are only required at the ends: the TPS and Dash.

Now:

Code: Select all

CAN TPS > ====== MCU ======= < Dashboard
PC > ========== /   \ ======= < ABS sensor

Terminations are required at the TPS, PC, Dash and ABS sensor.

Similarly:

Code: Select all

MCU > ====== TPS ====== < Dashboard

Would require terminations at the MCU and Dashboard.

[AndreyB]

So, CAN bus requires 3 logic-level wires (with some shielding probably?)
Disco board can be assigned with its own user-defined CAN address?

CAN uses two wires. CAN is just a transport bus - there are multiple reasons why ONE DAY we would need it. For instance, if stock instrument cluster receives data via CAN - we would need to provide it via CAN.

[AndreyB]

Finally assembled the module. It works

The silkscreen is too small, we would need to make it larger. A screw-in terminal on the CAN side also be cool - we can keep the 2.54 input pins, just add a screw-in terminal as a second option.

[puff]

some pads unpopulated?

[Art_ELectro]

some pads unpopulated?

It's pads on power line, see shema.

[puff]

just two caps and a LED with resistor?

[puff]

why do we need this power line stuff, what does that electrolytic smd 4,7µF cap looks like? is it necessary to make it electrolytic?

[AndreyB]

I am using part of the donated funds to order a second revision. The boards is functionally identical but the silkscreen should be much more user-friendly:

[puff]

shear waste of time&money
waiting for my version, planning for a trip to the chips store.

[AndreyB]

I do not think it's a waste of anything - I want to create a universal and usable platform. Assembling everything from the individual modules is one of the approaches.

[puff]

as far as i remember these small boards were suggested as a transitional stage before before a larger universal board is developed. since that small one was working perfectly, there seemed to be no need for further not feature-related improvements, cnsidering that final goal was to move these small boards onto a larger one.

[AndreyB]

Yes, kind of. But since we have these small boards anyway, I want to get them to a nicer state so that people can still use them as individual boards if they choose so.

And we still need good silkscreens so that next version of Frankenstein which would be created from the next versions of module is better

[puff]

just received the boards. could be even faster (sent on february 24?) - I made an error in postal code (the last digit)

IMG_20140315_152846.jpg (258.79 KiB) Viewed 14091 times

I thought it was made in the USA, however, the parcel came from China
this large parcel!

IMG_20140315_152721.jpg (308.05 KiB) Viewed 14091 times

probably, next week I'll have a trip to the local radio shack store

[kb1gtt]

I don't think radio shack sells SMT resistors, so I don't think you can get any worthwhile components at ratshack.

Yes OSHPark is from China. They put all the PCB's on one large panel, then have that panel manufactured. What surprises me is that they shipped direct. They used to get the panel here in the states, then they broke it up and ship individually. I guess if they can break it up in China, that helps keep the shipping costs down.

[Laen]

I don't think radio shack sells SMT resistors, so I don't think you can get any worthwhile components at ratshack.

Yes OSHPark is from China. They put all the PCB's on one large panel, then have that panel manufactured. What surprises me is that they shipped direct. They used to get the panel here in the states, then they broke it up and ship individually. I guess if they can break it up in China, that helps keep the shipping costs down.

Hi! I'm Laen, and I run OSHPark. Our boards are (and always have been) made in the USA. As someone deeply concerned with environmental and labor conditions, there's no way I would ever manufacture them offshore.

[blundar]

Dude, your information is wrong. OSHPark manufactures all their PCBs here in the US. They may use some packaging made in China, but the PCBs are all USA. The guy that runs it is a huge proponent of open source hardware and developing manufacturing here in the US. Double check before spouting off next time, ok?

[puff]

then it first was shipped to china and relayed to russia. i received that parcel from china, not the usa...

[kb1gtt]

I also seem to recall the return address was from China, not the USA. However it's been a while sense I ordered from OSHPark, so I can't confirm the packaging. I see on the OSHPark web page, it claims it's USA MFG. However they also claim you get your boards shipped in less than 8 days. I also don't recall a delivery time being that short. I seem to recall it was close to a month before the boards were delivered. I've been finding the china PCB assembly service(s) are handy as I'm time limited. I'm not sure when I'll my next OSHPark order, so I doubt I'll get to double check the sourcing any time soon. It's not really important to me where they are MFG'ed.