Diagnostic Interfaces

[Rhinoman]

Thats fantastic news. When I started with mine I didn't even know if it had diagnostic capabilities. I found the format whilst working though the disassembly. Now it looks like we have this well and truly hacked. The questiuon is how many more Suzukis does this work on?

[Rhinoman]

The British motor industry was developing and producing lean burn engines in the late 80s early 90s. There was a big debate as to whether lean burn or catalytic converters were the way ahead. The British government supported lean burn but the EU decided to bring everyone in line with the US by introducing legislation to make cats compulsory. One interesting thing is that the manufacturers increased engine capacity on nearly all lean burn engines. 1.3 engines became 1.4 and 1.6 engines became 1.8, I did think that that was to retain performance but it may have been coincidental and related to EU taxation classes..

[Rhinoman]

Originally Posted by jtgh

I noticed this same number is used in the OBD2 protocal too, (legacy equipment supports that , so they used it. even today on new cars)


notes, my special rs232 card allows the illegal baud rates as does realterm.
a perfect match.
the "comes-with", IBM clone style DELL UART can NOT generate this queer baud. the ubiquitous N16550a is useless at 15625. Com1 and Com2.

One nice thing ,the realterm proggy will tell you , if the baud is legal.
just plug in the card, and try it, it will say," illegal setting to com1." if true.

OBD1 , for Suzuki, coming soon and free of charge. (cept hardware)

cheers.

OBD2 is 10200 baud. The old MUT protocol was 15625.

I'm surprised that the Dell chip cannot generate odd baud rates, are you sure that that is not a problem with a windows driver. I have software that can drive the UART directly at any baud rate. I use standard Windows rates and ASCII serial transfer because it means that any software (is Hyperterminal) can be used as a back up. I will also be using my software for OBD2 and for reprogramming also so it is preferrable to have my own protocol to an active interface. I will publish details and if there is any demand then I will produce a batch of scanners. I figure that most people will want to buy rather than build so they may as well buy from the guy that did the groundwork.

I wrote datalogger software some time ago but two hard disc crashes in two weeks meant that I lost a fair bit of the code. The basic framework is still there and I started creating my own gauges too. If you like I will send you this, it is written in Borland Builder 6.

[jtgh]

I am sure, it fails in DOS, Linux. windoz and ASM 386 machine code. ( its a hardware thingy)

THANKS FOR THAT ! MUT, yes, but my point was why 15,625? (Ans: 1E6 div 64 ! 6850)

Chips !: (those little details in electronics) UART's (serial ports to most or COM1)
Legacy:
that's easy,the 16550a (have datasheets , all versions 8250 (xt),16450, on up)
I have the full spec and schematics for all IBM PC's, from which all were cloned.
Lots of Legacy data I have.....

this problem, is the frequency of the master clock used for the PC.
1.8432mHZ. (IBM PC spec, for XT , AT and PS2) ( and its errors !)

the 16 bit DLM+DLL register sets the output rate. clock div by 16 div by DLM+DLL.
the correct load in to that reg for 9600, is 0012 (max speed on an IBM-XT, oops)

the 19.2kb is code 6 . (Msb = 0) LSB = 6.

others:
code , rate:
---------------
12 = 9600
11= 10473
10-= 11520
9= 12800
8= 14440
7= 16457
6 19.2k

as you see?, you will need to load a number between 8 and 7 and that will never happen.
not on legacy or on any clones ( heck the new PCs have dropped the port)

Realterm (tm) is cool, it writes it out and reads it back if it can come back , error.
Plug in new PCCard(pcmcia) and bingo , solved !
The old UART's could clock at 8mhz but IBM choice was 1.8mhz. (they had reasons)
Joe Campbell has a great book on that.
I worked at INtel when IBM was buying all our chips and even the broken ones, 8088.
500,000 a year was really over the top back then,.

NEW CARDS: (Uarts)
how ever, with a ADD-in CARDS, rS232, MANY have a very fast clock, (MOST)

The Dell is spec'd at 19.2k baud max , and if you try to run it above that, like
115k (code =1) baud like our MegaSQUIRT fans did , they found out this doesnt work.
(some do , many dont) they sell a USB Uart and that works perfect.

the data sheet for the 16C550a chip says , at 38400 (code 3)is max speed ! , the error will be beyond the EIA values of -2.5 and + 4%. ( says it plan as day)

the error is in the UArt and the crystal, as most xtls are very inaccurate and dirt cheap.
and veries from one clone mfg to the next, (sadly)

the add in cards, usb, or pccards , have a dual range UART, (cool) and allow speeds up to 1.5mbps and beyond, and accurately (what a concept, accuracy).

IBM:
the error at 56000 baud is 2.86% (ns16550d) and states that the next two higher are illegal. ( the dashes in the table ,mean , dont do that)
that considers an almost perfect crystal. (actually, so is 56k if it falls below -2.5%)

I say this ALL , because my last post , i got tons of email from developers wanting to know what I know about legacy PC's. (RS232 is not dead, just in the office !)

Many get confused by that,because to PC's running Laplink(tm) at 115.2k baud work great that is because they are both in error the same amount (2 wrongs can make a right) the "shift register" in side is happy. ( the net result is no framing errors)


yes, thAT windows software is nice, I have Visual C++ too, and can code like crazy.

But , I diverged:

the only issues (secrets) are filling out the address map,
function versas , index pointer code (3rd byte of 4)
once the this is done , the software is , really, a piece of cake.

refr:
15mpbs rates , no problem (ADD IN) even faster and fully downward compatible.

rs-232 pc-card pcmcia, Computers Networking, wii items on eBay.com

$15 and will do magic.

When i get the map done, i will give away the whole store, all for free.
Demand is low.
But those wanting to fix their cars , and want a better analytical tool, it is comming.
all you will need is 3 pieces of hardware.
cable, adaptor, and the above mentioned PCcard so that 15625 baud will be dead nutz right on.

best advice for anyone is to simply plug in a quality modern Addin RS232 card , pccard.
that legacy junk, is just that.

cheers.


PS:
one more issue, that is the PC talking to any modern equipment at high rates of speed.
the new equipment will be dead accurate but the PC will be way off in frequency. This is why people get so surprised.
Any thing over 38.4k can be an issue.
Best is to measure the error, or swap in quaility hardware.

[jtgh]

hypertrem is weak ( it's for a modem and is not a useful tool ) (very limited)
I have one that i wrote 10 years ago in 80386 masm. it is better but will not support
illegal baud rates.

Terminal Software

its free too. (mostlY) (notice the very flexible display format !!!)
I did license mine so i can get the active X support.

First order, is to pluck the turkey. (hacking the ECU)

[Rhinoman]

I haven't had any problems with my PC running at 115K2 (its not a Dell) but I only did initial development using the serial port. My laptop has no serial port and my interface is USB so its just plug and play. An active interface can scan the connector pins to see which protocol is present. Initially I will support just the Suzuki OBD and SAE J1978 but the design can be expanded for other protocols too. The concept is little different to the industry standard ELM chip. I have published the design for the interface and will publish the firmware too. My intentiopn is to encourage people to experiment with the EFI system, in the UK too many people just rip it off and fit carbs.

[jtgh]

Thanks !
yes, some newer computers ,PC clones ,etc, have the new fancy dual range Uart chip.
Realterm has a hidden switch for that , just rightclick Baud box. (scaler option)

that is what is in most USB-232 converters, have is the better expanded UART with the extra fast clock , that why you call up illegal bauds.
illegal as in not IBM spec, not in any EIA/TIA spec.)

are you saying you have a turn key system working? OBD1 Suzuki?
if yes sell me one and save me all the trouble of reverse engineering my ECU.
although it is fun, (& an insomnia time killer, LOL)

if you need help, let me know.


I am familiar wthe the ELM chip and all the free software that is avail. to support it.
really nice design that is. and public interface protocol.

try a D600, or a cpxi, PPX or ?, I have this huge list of Laptops that cant go fast or queer bauds and still run the old 1.8mhz clock.
if it has only a 16550x , it will not work,that is a given.

thanks for sharing, !

let me know about your package?. I am interested.

I want to spend more time anyway with my megasquirt turning some more and getting
my custom idle modulator to work.



cheers, and thanks for the info.

[jtgh]

yes , id like to try that.
I am an old Borland turbo C guy,
if it works I will send you a new DVD burner so you can back it all up and not suffer loss.
4gigs gets most of it all.
cheers

I wrote datalogger software some time ago but two hard disc crashes in two weeks meant that I lost a fair bit of the code. The basic framework is still there and I started creating my own gauges too. If you like I will send you this, it is written in Borland Builder 6.

[jtgh]

i worked on the address map tonight.

0x13,0x04,cmd, cs

for cmd, index i found:
09 = ECT (cts old name)
0A = IAT (air temp sensor)
0c = TPS ( 00-c6 hex data range ) ? volts 0 to 5.1 is spec.
0D = TPS (00 -ff hex data range) ? degrees angle 0-90 is spec

0F = start switch, says cranking to ecu.

10 and 11 are related to RPM or injection or spark advance (wip)
12 is BARO, it varies all by self with key on, engine off.

as you found 1A is system voltage.


more work to do on this, but I found 4, plus the mate to the TPS .

does this help or have you found them all , already.
thank for your data.

cheers, jerry

[Rhinoman]

I need to check my notes to see where thee ATS and WTS are.
05 I have as RPM/4
0B is read from programme memory not RAM - possibly model ID.
0C and 0D agree with what I have.
0E is an analogue input not implemented on mine.
0F I have as the inverse to RPM, possibly the CAS.
12 is MAP, varies with engine running.
14 is maybe fuel enrichment or idle speed control
1A is Battery Voltage * 0.0737288
1C is a status register, bit2 maybe Fuel pump
1F is a Port. bits 5 and 3 are used.