Pseudo code, strategy for CAN PHEV control methods?

Not a clerk nor a cashier. I did some industrial PLC programming as an intern in the past but that was very basic and routine stuff and a very long time ago.

I bought an ELM327 interface december last year. Similar to this one, but the older 1.3a version: OBD Diagnose Interface ELM327 USB CAN VAG BMW Audi ALU - eBay, Computergestützte Diagnose, Handmess- Testgeräte, Werkzeuge, Auto Motorrad Teile. (Eindtijd 26-apr-11 11:05:30 CEST)
I was told the software that comes with these gadgets were really bad (haven't tried it myself yet). So I started programming very simply in VB6, made a virtual COM port via USB and my intention was to put the laptop in the car, connect it to the CAN bus via the interface and see if I could get any relevant data that was specifically interesting to me on the screen. Somehow I never got that far, little spare time and at the time it was freezing cold over here.
I have a transciever with CAT (Computer Aided Tuning) so I could test my homebrew program without having to go out in the cold, and check if I had a COM port connect and switch between transmit and receive. CAT uses the 7,N,2 protocol so I made the bits, parity and stop variable in the program using comboboxes and including the possibility to add a handshake like Xon/Xoff to the protocol.
So I could basically press the Push To Talk button of my transciever with a mouse click. To my surprise that worked straight away so I added more buttons which switched to different frequencies in a few millisecond intervals. And got that working as well. But that is where my experiments ended.

I assume the ELM327 (and the 323 and ELM5) will use the standard 8,N,1 protocol. So it's reasonably easy to start, now it's a matter of figuring out how the OBD2-CAN bus protocol works and getting the data we need.

Soon I will have some more time on my hands and temperatures are nice right now. I also read pEEF's stuff but I don't think he will share the details. But I'm game if you can tell me a little more about how to intercept CAN ODB2 data. Always eager to learn and I don't mind sharing the source at all.

If you don't mind starting off in a simple language evironment like VB6.0 we could figure out what data we need, how to intercept it, where to get it from and at a later stage see if and how it can be influenced. At least that would be a start.

What exactly is your objective: allowing the car to drive at a higher speed in pure EV mode? Personally I would like that too but don't know if that is possible.

I will try to get the ELM327 to work first thing next week. Laptop on the passenger seat and see if I can get some data off the bus using the standard software first. If you're interested going down this road let me know, okay?

If you already have some kind of interface and you can use VB6 it is quite straight forward: use the MSComm control to connect to the virtual comm port. From there it's all a mystery to me...

 

I know a little on how CAN works and am learning more as I use an Arduino UNO and a CAN shield. The shield manufacturer has a demo .PDE CAN program probably written in C which may help with the learning process.

The transition to LIN will have to wait while I learn.

 

It could but not easily as ther are no jumpers that you can move around to change cs , int etc on the CAN -BUS shield that I am using.

The SiLabs and Microchip CAN demo boards have 2 CAN interfaces which can be interconnected to form a bus OR kept separte to form a BRIDGE.

 

Sound like a good way to trick the Prius in stopping it sending fuel Lesdit, it might just work. It also seems a good idea if you take the firmware road and I stick to the software approach. We can still exchange knowledge that way. Like you said; there are so many Prius on the road yet so little information to be found.

I know a little about the ATtiny AVR, as a matter of fact there is a chip like that in front of me on the table. I wanted to use it to make a robot lawn mower using an old kid’s car, but it’s another unfinished project due to the lack of time.

This afternoon I had some time and put the laptop in the car. The reviews were right, the software provided with the ELM interface is basically worthless. For some reason they don’t recognize the virtual com port. So I downloaded an evaluation version of PCMScan and it connected to the port immediately. The problem is that this program is not really suited for hybrids like the Prius. The only CAN PID it is able to show is the rpm of the ICE, it shows current values and average value. So at least I know the ELM interface works.
I used a baudrate of 9600, haven’t tried 38400 yet but that should probably work as well. It detects the CAN 11-bits identifiers. Three ECU’s are seen by the software: at $7E8 an Engine Controller, $7EA an unknown module and at $7EB another unknown module. To my surprise the first one is indicating OBD compliance: EOBD (Europe) standard and the last one as OBD-II (California ARB ). I hope the difference between US en EU Prius will not pose a problem, I expect not.

The terminal function of this program only works in the registered version. So I think it is best to write my own program in Visual Basic.

I used the same VB code as for my transceiver program, made some minor adjustments to it and put the laptop in the car, hooked up the ELM device to the OBD bus and: I set in to COM1: (in my case) and protocol 8,N,1. It worked like a charm. Don’t you love it when that happens.

In case someone is interested in the VB6 code I will explain a little here. The basic layout of the main form consist of several buttons (Combo_Click1 to 5) in which the speed, amount of bits, parity, com port, amount of stop bits, and handshake can be selected, they are given the variables: CANspeed, CANdata, CANpariteit, CANstop, CANhandshake . The Connect button has the following code:

Please ignore the remarks, they are in Dutch. The form has two images on top of each other. As soon as the connection is made the top image (Image2) is made transparent (Image2.Visible = False) and the blue Toyota logo below is shown. Also a sound is heard to indicate the connection to the serial port has been successfully made. As soon as the connection to the chosen port is made these settings are written in a CANconfig.ini file. Next time it will automatically use these last used values.

So the connection to the serial port is working. I still need to add a function to determine if there is any communication with the CAN bus through the port, that will be my next step.
A simple ‘atdt’ like you use to wake up a modem will not be much use. There already is enough traffic running over the CAN bus, I now have to figure out what to send and what I should expect as a reply.

But at least I started with this project again, hopefully some more to come within the next couple of days. Attached some screenshots of the program sofar. The TX and RX button can be removed and I think I will add two indicators that turn from red to green if connection to the ELM device and CAN bus have been established.


At startup


Connection established

CAN-quest seems like a nice title, hereby claimed as a trademark. If it is this easy to establish a connection to the comm port it makes you wonder why they added that crappy software with the ELM. On the upside it's fun to make something yourself.

@ Ccdicse: I have no experience with C(+) but some routines can be incorporated in VB. Since the next step is to send an signal over the CAN bus, can you tell me what would be a good way to check if there is a connection to the CAN bus?
I will use a syntax like MSComm1.Output = "message to can bus" & vbCr and txtDisplay.Text = MSComm1.Input to see what is returned.

 

Here there's my contribution to the cause and as fallow, are some 2nd gen Prius CAN parameters for you to play around:
CAN030 byte 5 brake position
CAN520 byte 4 X 3C8 byte 5 fuel flow
CAN039 byte 1 ICE temp
CAN03B bytes 1,2 main battery current
CAN03B bytes 3,4 main battery voltage
CAN244 byte 7 throttle
CAN3C8 byte 3 ICE rpm
CAN3CA byte 3 speed
CAN3CB byte 1 maximum charge current
CAN3CB byte 2 maximum discharge current
CAN3CB byte4 SOC
CAN3CB byte 6 highest battery temperature
CAN526 byte 2 VVTi
CAN52C byte 2 coolant temperature
CAN5A4 byte 2 gas tank

 

Thanks Mrbigh, it might be best to start with a simple variable like: brake position. Any idea how you would format them in a terminal program? That's what I'm trying to figure out.

 

Hi Floyd2,

$7EA is a response from $7E2 (HV ECU).
$7EB is a response from $7E3 (Bty ECU).

Here is an interesting link:

http://plasma2.ssl.berkeley.edu/sprite/hdh/_hdh_dwgs/Drawing_File/Old_Revisions/0199-ME02-J.xls

hope this helps

 

Thanks Vincent, very informative spreadsheet too. It's way past midnight here but first thing tomorrow I will try sending to these adresses and see what is returned. Don't know if they can be sent in hex or have to be converted to decimal first.

Problem is the battery of my laptop is really old and will last 10 minutes at most, so I will have to do the programming inside and if possible correct the first time.

I will let you know how it turns out.

 

I'm not familiar with your program but according to the ELM327 manual that I've read online, it can communicate with a PC in hex (not dec) using any terminal programs (HyperTerminal, ZTerm, etc). Since you're communicating with CAN bus, I think 9600 is too slow to be of any use. I suggest you change to 38400 baud instead.

 

I 've not looked at CAN traffic but according to Attila Vass, there are about 1650~1700 message/sec.

The new 2004 Toyota Prius : My CAN Project

 

There was a nice momentum but it seems to grid to a halt at the software front: I still have no clue in which format the CAN protocol expects to receive a request. Really frustrating, you would expect that someone must have tried this before or that some kind of information would be on the internet. I found a few questions on some forums but no one seems to have figured it out. Or maybe they did but never bothered to post it.

HyperTerminal is no good, it keeps asking all kind of irrelevant personal information, very annoying. RealTerm is a lot better, user friendly and all settings can be changed. I set the speed to 38400 which seems to be the max for the ELM.
Sending a hex value as a value doesn’t seem to do anything, when sending it in ASCCI the RX button briefly blinks so it seems the CAN bus (or ELM327?) is responding. Unfortunately shown as an ASCII or ANSI character on the terminal screen so that is not much use either.

Tomorrow I will try it directly from my own VB program, see if I can any response from the CAN bus. If anyone can find an example or code snippet in VB please let me know.

 

Found that the ELM327 datasheet contains detailed instructions on how to connect and about the OBD message formats, why didn't I think of that that before? It's 59 pages so this may take a while.

Datasheet ELM327: http://www.elmelectronics.com/DSheets/ELM327DSF.pdf

I wasn't even that far off comparing it with a modem, you can use similar 'AT' commands.

@Lesdit: RealTerm has a PicProm feature, don't know if you can use that for the microcontrollers you mentioned but it may be worth having a look.

 

Hi Floyd2,

That is the same ELM327 manual that I was talking about. You can find some of the AT commands in this thread:

http://priuschat.com/forums/gen-ii-prius-modifications/80206-canbus-pids.html

http://priuschat.com/forums/gen-iii...gging-obdii-can-data-any-recommendations.html