ECU Connection lead for Laptop
Discussion
Erich - Yes you need a standard RS232 Serial Cable DB9 Male/DB9 Female, like this...
http://www.cablewholesale.com/specs/10d1-03206.htm
The ECU connection is Female
http://www.cablewholesale.com/specs/10d1-03206.htm
The ECU connection is Female
The other pins on the RS232 port are input pins for the mapping of the MBE fuel ignition, and one sensor pin for a kind of feedback system to the ECU, and one pin to turn the fans of the car on for mapping purposes.
Although on the TVR MBE all this is effectively disabled, it does look like this can be re-enabled as one of the two ways to give ECU owners a functional ECU again.
http://www.mbesystems.com/softwaredownloads.html
If you read this link the warning they give is effectively that shorting these pins can cause damage to that part of the circuitry.
Its possible that owners using standard RS232 cables will only find the damage that may have been done if at some point in the future we collectively succeed in opening up the MBE to its original ability.
So, you are right that a standard RS232 cable will work with the TVR with no problems. But should we in future be able to ressurect a more functional MBE by changing its Eprom, then people who have used an RS232, that also happens to have the DTE loop wired as part of the RS232 lead or possibly have all the other leads earthed will have damaged that part of their ECU.
I know thats a bit vague, but its the best I got.
Although on the TVR MBE all this is effectively disabled, it does look like this can be re-enabled as one of the two ways to give ECU owners a functional ECU again.
http://www.mbesystems.com/softwaredownloads.html
If you read this link the warning they give is effectively that shorting these pins can cause damage to that part of the circuitry.
Its possible that owners using standard RS232 cables will only find the damage that may have been done if at some point in the future we collectively succeed in opening up the MBE to its original ability.
So, you are right that a standard RS232 cable will work with the TVR with no problems. But should we in future be able to ressurect a more functional MBE by changing its Eprom, then people who have used an RS232, that also happens to have the DTE loop wired as part of the RS232 lead or possibly have all the other leads earthed will have damaged that part of their ECU.
I know thats a bit vague, but its the best I got.
Interesting Julian - I bet I'm not the only one who has used a standard serial lead though. It seems to be saying that there is a possibilty that the ECU can be damaged, I'd like to know from someone like Jules (Trackcar) just what the risk is, and find out if I should get a proper lead made up and junk the old one - or has the damage already been done? 
Hmm, talking apples and pairs a bit here.
The dealers would use standard RS232 because they've never had a MBE box that didn't have that part of the circuitry disabled for use on a TVR, so they wouldn't know.
Jules rarely uses a mapping box these days because as I eluded to in my previous post it is only one of the two possible ways to map, well, three is you count austec.
I believe Jules would be using live mapping which is a command set via the computer and therefore dispenses with the mapping box altogether, just uses the RX TX and ground on the RS232 rather like the TVR original diagnostic software, but with more capability.
I think my original post said something along the lines of , 'I hate to say this, but', Well now you know why
.
So to recap.
If your MBE is always going to remain standard go ahead.
If your MBE is only ever going to be used with Live Mapping via Jules go ahead.
If you've been using a standard RS232 lead all this time then if it is likely to have done damage it will have done it already. ( The only damage I can see from the circuit is like to be a dead capacitor which can be replaced, but possibly a damaged port on the processor, which can't)
If you have an inkling that we will want to restore mapping box capability to a TVR graunched MBE and make it more like an original, then the warning from the manufactures website should not be ignored, and you should keep you MBE protected with an officially wired lead in case thats where we go.
Jules is probably right, given the ability I guess most will end up live mapping, which I doubt could be affected no matter which lead you use. But the ability to map the car using three simple potentiometers would be lost if that circuitry got damaged.
The dealers would use standard RS232 because they've never had a MBE box that didn't have that part of the circuitry disabled for use on a TVR, so they wouldn't know.
Jules rarely uses a mapping box these days because as I eluded to in my previous post it is only one of the two possible ways to map, well, three is you count austec.
I believe Jules would be using live mapping which is a command set via the computer and therefore dispenses with the mapping box altogether, just uses the RX TX and ground on the RS232 rather like the TVR original diagnostic software, but with more capability.
I think my original post said something along the lines of , 'I hate to say this, but', Well now you know why
.So to recap.
If your MBE is always going to remain standard go ahead.
If your MBE is only ever going to be used with Live Mapping via Jules go ahead.
If you've been using a standard RS232 lead all this time then if it is likely to have done damage it will have done it already. ( The only damage I can see from the circuit is like to be a dead capacitor which can be replaced, but possibly a damaged port on the processor, which can't)
If you have an inkling that we will want to restore mapping box capability to a TVR graunched MBE and make it more like an original, then the warning from the manufactures website should not be ignored, and you should keep you MBE protected with an officially wired lead in case thats where we go.
Jules is probably right, given the ability I guess most will end up live mapping, which I doubt could be affected no matter which lead you use. But the ability to map the car using three simple potentiometers would be lost if that circuitry got damaged.
You're gonna hate this but to further add to the confusion .. I also have a mapping box which i also use with std serial leads. It's useful because it allows much faster mapping changes than key strokes so if you have a car that's being mapped for the first time and is miles away from where it needs to be I'll use the mapping box .. if it's a tweak on the map ie small changes I'll use teh key stroke method. The only reson these days that teh mapping box doesn't get used quite so much is that I have a few chips to choose from which will get me very cloe in just a few runs, then I attack it with the keyboard. It's easy to count keystrokes to get back where you started.
Well thanks chaps, that answers my questions then some, the sound of cans of worms being ripped open is clearly audible!
Julian64,
Does this future opening up the MBE to its original ability apply to the 4.2 or just the 4.5 engine?
Surely if TVR dealers have always used standard RS232 leads then chances are its very unlikely there are any Cerberas that by now have not had their ECU connected up using standard RS232 leads so they have probably all sustained the damage your describing?
If you ever do crack the MBE problem can't your improved assembler code just be copied onto a fresh new chip?
Julian64,
Does this future opening up the MBE to its original ability apply to the 4.2 or just the 4.5 engine?
Surely if TVR dealers have always used standard RS232 leads then chances are its very unlikely there are any Cerberas that by now have not had their ECU connected up using standard RS232 leads so they have probably all sustained the damage your describing?
If you ever do crack the MBE problem can't your improved assembler code just be copied onto a fresh new chip?
No, thats okay. The standard lead you are talking about would be a nine pin . Pin-pin which is fine if you have a mapping box controlling the ecu depending on how your mapping box output are config'd.
You couldn't control the ECU from a mapping box with just a TX RX and ground wired in it. Laptop yes, mapping box, no.
Well, if you could, I would feel compelled to sit down and cry.
You couldn't control the ECU from a mapping box with just a TX RX and ground wired in it. Laptop yes, mapping box, no.
Well, if you could, I would feel compelled to sit down and cry.
Edited by julian64 on Thursday 24th April 19:13
So what are we saying here then....?
It's OK to use a standard serial lead....
If the Car is Standard
If the car is going to be mapped by Jules
If the car has been mapped by Jules
But, there is an element of Risk, if in the future something gets developed that allows - and this is where it started going way over my head - "3 potentionemomomenymeters thingy's" to do magic stuff on the MBE chip?
and if I've used one already, I'm F**k*d anyway
It's OK to use a standard serial lead....
If the Car is Standard
If the car is going to be mapped by Jules
If the car has been mapped by Jules
But, there is an element of Risk, if in the future something gets developed that allows - and this is where it started going way over my head - "3 potentionemomomenymeters thingy's" to do magic stuff on the MBE chip?
and if I've used one already, I'm F**k*d anyway
Edited by JensenA on Thursday 24th April 19:04
'Erich', the assembler code is on the Eprom. the chip 'brain' processor just runs it. The eprom is easy to swap. The processor would be an absolute bugger to swap if damaged. Changing the code that the processor runs is just changing the eprom. There is no code inside the processor itself.
'Jens' yes to everything.
My answers will get more definitive with time, but are a bit murky currently. I just couldn't let another thread pass that said you'll be fine with a standard lead. The manufacturers website says no, and I think I can see why. The answer as to whether you use a simple lead or not, is not so straight forward as you can see, but the official lead is so easy to make, and clearly shown on the website, why not go the extra mile?
'Jens' yes to everything
.My answers will get more definitive with time, but are a bit murky currently. I just couldn't let another thread pass that said you'll be fine with a standard lead. The manufacturers website says no, and I think I can see why. The answer as to whether you use a simple lead or not, is not so straight forward as you can see, but the official lead is so easy to make, and clearly shown on the website, why not go the extra mile?
julian64 said:
You couldn't control the ECU from a mapping box with just a TX RX and ground wired in it. Laptop yes, mapping box, no.
Well, if you could, I would feel compelled to sit down and cry.
No need to cry Julian. The mapping box does require the fuel, ignition and boost trim pins plus the trim ground to be connected as well as RX/TX/GND for the lapptop to ECU control.Well, if you could, I would feel compelled to sit down and cry.
The direct to ECU live mapping just requires the RX/TX/GND.
The lead with the resistors at the ECU end as described on the SBD site puts voltages across the trim pins. So it would depend on what the mapping box settings were as to whether the resistors would have any impact on the fuelling or ignition. The standard (non Red Rose) ECU has the mapping box trim inputs disabled but the Red Rose has the ignition trim enabled. Quite how that would interact with the mapping box I never worked out. (But I think when off there was no voltage applied to the trim pin) Joo and I did consider an after market 95/98 RON switch but I never got to dismantle a Red Rose to find out exactly how they had wired it. But any of the standard ECUs could be fitted with it. I'll have to get a cheap eprom blower and have a twiddle. Joo, next time you get a Red Rose car in can I dismantle some of the wiring harness?
Edited by mikesr on Thursday 24th April 20:27
trackcar said:
Mike I do believe you've just given Julian the missing piece of the puzzle he needs to crack the ECU 
he was so close anyway it was almost painful to watch. Julian and I exchanged a few emails a couple of weeks ago. Julian had already worked out what they had done by looking at the memory addressing in the assembler.
He has already overtaken my limited understanding.
He can already cross compile from his assembler dump - something I never got sorted
He has a complete wiring diagram of the ECU
and he's well into commenting the assembler
I believe he will recompile a new binary at some point (rather than just patching it like I did) and be able to add new features to the ECU!
I was quite happy to find the very small number of places in the assembler to do manual patching and get the mapping working.
Now I need to buy a 4.5 so I have a Cerbera that can benefit from all the work we did
Well gee thanks mike, here I am sitting in a pile of paperwork up to my elbows trying to figure out simple crank timing, and you reckon I got it all done.
Honestly, since we emailed the paperwork has sat dormant with me making a small cicuit board for a pic chip running a USB and an SPI port talking to a load cell to get my corner weighting working on the laptop.
A working cross compile of the code I do have.
A working circuit diagram of the ECU I do have.
Commented code, about 30% now.
Complete mastery of mapping, I am still a long way behind you. I think I know how it works but not tried to prove it yet. You however cracked the bit most owners wanted to know way back. Coincidently just about the time Jules was offering it as a service so don't be modest
Honestly, since we emailed the paperwork has sat dormant with me making a small cicuit board for a pic chip running a USB and an SPI port talking to a load cell to get my corner weighting working on the laptop.
A working cross compile of the code I do have.
A working circuit diagram of the ECU I do have.
Commented code, about 30% now.
Complete mastery of mapping, I am still a long way behind you. I think I know how it works but not tried to prove it yet. You however cracked the bit most owners wanted to know way back. Coincidently just about the time Jules was offering it as a service
so don't be modest you're both clever cookies Wish I knew what the heck you were on about
it was a brief convo about the way the red rose switch worked that alerted mike to how we could get the mapping box up and running .. when you were asking about the red rose cars earlier I felt sure you'd realised that bit too .. good work both you guys, the depth of understanding some people have outside their chosen careers is astounding
Wish I knew what the heck you were on about it was a brief convo about the way the red rose switch worked that alerted mike to how we could get the mapping box up and running .. when you were asking about the red rose cars earlier I felt sure you'd realised that bit too .. good work both you guys, the depth of understanding some people have outside their chosen careers is astounding
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