FT232 rs232 to usb converter.

[dr pepper]

I want to communicate to a vehicle ecu with a pic via rs232.
Using a ELM327 protocol converter ic designed for the job this is a simple task, to get basic data anyway.
You used to be able to get a cable that contained a obd diagnostics connector, a elm327 chip and a d9 on the other end, but nowadays you can only get them with a ft232 rs232 to usb converter chip as well and a usb connector, due to the fact most slaptops dont have a serial port.

I was wondering on the feasibility of hacking my usb to obd interface and bringing out the rx,tx,dtr and cts lines from the ft232 (I know its an ft232 inside the interface as windows 7 tells me it is).
I have a pic programmer that is rs232 or usb, there are links you position for rs232 or usb, I suspect the links just connect the tx and rx from the ft232 chip (it has one too) to the rs232 connections on the on board pic controlling everything.

 

[dr pepper]

Its ok I sussed it.
I cut through the tx pin on the ft232 and bent it up, as its low impedance and would mess up comms, I left the rx pin on the ft232 as is and everything else for that matter.
I then connected the rx and tx pins of the elm327 (actually a pic) directly with a couple of bits of wire to my usb to rs423 converter (rs232 but 0 and 5v instead of + and - 12V), and it works.
If I now connect a pic to this I'll be able to communicate with the vehicles ecu with a pic using a uart.
I'll still be able to use the obd interface as obd to rs423, or I could resolder the tx pin on the ft232 to put it back as was, which is unlikely as the interface will now become a part of this project.

 

[Mosaic]

What are you doing to the ECU?

 

[dr pepper]

Nothing.
I did what I wanted, just need to tidy up the display.
Most obd interface modules contain a elm327, it converts one of 6 possible ecu comm protocols into rs232, a lot of manufacturers put a ft232 in with the elm327 to make it usb, or even nowadays a rs232 to bluetooth converter (for tablets).
The protocol is not hard to understand.
I want to display parameters from the engine, just about every one I can, so that possible problems with cats and sensors can be found, and using a fewquids worth of hardware instead of something £££'s.
My device now displays 8 parameters on an lcd, I'm just having to suss out long term and short term fuel trim protocol, some weird scaled 2's complement thingy.

 

[dr pepper]

Well heres the prototype:

Theres an led round the back to indicate open or closed fuel loop.
The ecu in my car must be kinda busy as it takes around a second to update the whole display.

 

[large_ghostman]

Good work! I wished I had known though, I did something like this 4-5 weeks ago, there is a easier solution
**broken link removed**
you want the 502 I will try and get pics later of the cards but I dont have a empty SD card for the cam which is why my pics are stacking up!
there is also source code on the site and all I did was tweak that and push some wire's into the socket, if you have the correct plug though you can make it neat. The elm chips around have a bug in them as they are clones from something else and hold the ver1 firmware, I will scour my book later and give you details.
I have had mine talking to a new Vauxhal Astra, a oldish landrover freelander and a john deer tractor, its currently sitting in the tractor fault finding . I am using it to log the data onto the laptop via the card itself. they are cheap and once you buy one programing dongle thing (not really needed) all there daughter cards fit it! you only need the dongle/stick thing for programing or it can be used as a usb to 232 conveter as well, the daughter cards are cheap cheap cheap!

All the same nice setup

LG

 

[large_ghostman]

Forgot, what car is it on? you can get most codes and protocol information from main service dealers or the net. I got the freelander codes from a web site, most the temperature stuff I found was 2's compliment but there was also a code for the converted data.
I also manged all the air bag info and seat belt stuff on the Astra, as well as the EGR data and the oil life and level, I got bored before adding the washer bottle and stuff as that seemed pointless! It interesting watching the display when its driven and the ECO button is on, the car turns the engine off at traffic light etc, the ECU pumps out masses of data when it starts again

ASK me very nicely and I might help you change the millage

 

[dr pepper]

Its a very lowly cityrover.
I'm not concerned with milage and I suggest you stay clear of that sort of thing.
Never heard of the toolstick, mine is just a elm327 and a 16f628 programmed, nothing else, I probably wouldnt have done it any other way.
Access to the egr system and the emmision control is kinda usefull.
Interestingly I found and rectified a couple of minor faults on my car since I got this to work, the short and long term fuel trim are kinda usefull for that, esp when you do things like disconnect an injector one at a time and see what effect it has on the trims, you can test the injectors within a % this way.
Absolutely no info is available for my car, the only thing I know is that its similarish to a pug TU engine.

 

[large_ghostman]

Its a very lowly cityrover.
I'm not concerned with milage and I suggest you stay clear of that sort of thing.
Never heard of the toolstick, mine is just a elm327 and a 16f628 programmed, nothing else, I probably wouldnt have done it any other way.
Access to the egr system and the emmision control is kinda usefull.
Interestingly I found and rectified a couple of minor faults on my car since I got this to work, the short and long term fuel trim are kinda usefull for that, esp when you do things like disconnect an injector one at a time and see what effect it has on the trims, you can test the injectors within a % this way.
Absolutely no info is available for my car, the only thing I know is that its similarish to a pug TU engine.

I bet there is alot of information , try car chipping sites etc, I found all sorts out from a chipping forum. It turns out most systems are pretty standard and most companies offering chips etc have with loads of info. The Astra is the one with a huge amount of data on the bus, but its not a year old yet so I am not allowed to mess with it. The freelander is cool but basic compared to the Astra, the tractor is ace you can mess with all kinds of settings

 

[dr pepper]

My car is old for its age, it was built by tata motors pakistan, they use old hat stuff.

The obd bus is a K bus, the oldest form, it only supports the most basic of the obd commands, the fancy stuff tends to be on cars with a can bus.
There are 6 diffo buses the obd connector can use.
There might be some extra manufacturers data available over the bus.
Some of rovers ecu's, like the mems have several maps within them and you can switch them around, sounds cool.

I have tuned engines in the past and fitted aftermarket ecu's by the likes of lumenition and dta.
Interestingly one of the quickest cars had a dta system which was very simple, the injectors were batch fire, all 4 at once, it only used a map sensor, throttle pot and rpm nothing else, there is actually a lot less on race engines than prod ones.

 

[large_ghostman]

on the info for the link I gave you there was a datasheet I used (somewhere), you can connect and talk to any of the 6 buses by tweaking the firmware, thats how come I managed to talk to the three different ones here. The pic version you have used old firmware that got pirated, the board I linked to is just a 8051 with a can bus on it, its purpose is to show off a range of different chips uses a single dongle thingy for debug and programming, then you just by 'daughter cards' for the other chip samples they do. I have a few different daughter cards they sent me, really cool company.
I am making a new control/monitor system for the tractor, new tcho and speedo and all the other stuff on a colour graphic touch screen, the idea is to do away with the current switches and dash board. The tractor is a bit old and dad got it very cheap for "rough work". I decided time to learn more on tractors and my little Kabota dosnt have any electronics, so its play time on the john Deer tractor lol, I am not allowed to play with the huge MARSHALL 408 he has though .
Great fun messing with the ECU though

 

[dr pepper]

The K bus my car uses is kinda slow I only get 3 readings a second, hopeless for tracing vacuum or o2 sensor readings.

I use a usb 'scope for looking at o2 sensors and manifold pressure sensors, as well as ignition pulses and the like.

Colour touch screen, very nice I'd like to see that working.

When I was your age I used to help out harvesting and silo, I got to drive a 1942 massey, or on occaision a county which had 6' diameter wheels all round and was a real handfull, everything them days was mechanical, not a processor in sight, you could start the massey with the electric starter, hand crank, or a shotgun blank carteridge.

 

[large_ghostman]

Over the weekend I am picking up a new sd card for dad's camera, we only use the cards once then keep them, when I get it I will add it to the list of pics I have to do. I based the screen side and that on a EMF Gecko32 bit chip, as we have a Dev board for it with a touch screen on it, I took the screen off and used that with a smaller Gecko STK board, this talks to the 8051 board over SPI. Sometimes the 32 bit and 8051 stuff is easier than pics, there is a great deal of books and information on ARM Cortex stuff which helps alot.
When I get better I want to add in a animated graphic speedo and tacho to it. I was able to mess with the hydraulic pump settings, but dad made me leave that out as being too dangerous. The rest of the switches I need to keep like electronic DIFF LOCK I am going to do as cap touch switches under smoked back lit acrylic. Its a old tractor but a good test bed for me, plus you cant really do much damage to it.

I also have one of these (3 actually)
**broken link removed**

I might put in auto lights on the tractor with it, and for no real reason have the UV index displayed with the cab temp and outside temp, the fan and heating for the cab will also be manual or auto

Its the same chip I have in mind for the badge thing

 

[dr pepper]

Super.
I work with hydraulics a lot, presumably the controls are for proportional relief valves and the like, ok messing with them if you know the limits.
And I thought I was clever using a cds cell to switch on the backlight for the lcd.

 

[ghostman11]

hi he isnt about anymore but i did help with the tractor MY TRACTOR! the hydraulics he means are the main pump pressure valves for some reason the JD tractor we have has a setting for pump pressure and relief valve set point. i have no idea why its even there as a setting to be honest. the tractor is much better to use now it has the new gauges (screen) the only change i will make is to put it all in one of those sealed box's you can drop in water.

 

[dr pepper]

Well it was either servo pressure relief or proportional directional valve.
Being able to set pressure electronically isnt a bad idea.
There is often a valve on the pump and a seperate lower pressure relief valve, relying on the pump all the time can cause failiures if something goes wrong, also the seperate valve might be a reducing valve rather than a relief, this means you can have 2 pressures for different jobs.
An IP68 box is a good idea, gewiss make a load.