Hacking the DataStream

[EagleMark]

It's as steady as 160 baud data!

Here's the ADX, XDF, bin and data log. I took out conversion and played with it a little. Bottom line is numbers go up with load and down on decel. I put it in drive foot on brake and gave gas, watch vacuum drop and BPW goes up, vacuum goes up and BPW goes down.

[gregs78cam]

That data still does not look quite right. To go from .061 to .004 and back up, that just isn't right. I need to come by on Friday before work and try a few more things. At idle, with 160 baud it should stay almost rock steady at something, it is changing by a factor of 10 when it shouldn't be. I need to do some work with this.

[EagleMark]

If you look it changes at idle as idle changes, 25 or 50 RPM. Remember how slow 160 baud is? Your used to smooth 8192 baud data... 160 is IIRC every 1.2 seconds...

[gregs78cam]

Yea I get the 160baud, "tune by braille", but the values don't seem anywhere close to what they should be. Do me a favor and tomorrow, try changing the XDF values to "BC0EBC0F", using the attached ADX make a log then change them to "BC3CBC3D" and make another log. Then post back.

[EagleMark]

Do you a favor? Ha! I thought you were doing me a favor?

OK but you really got me going on some things I have wanted to learn to do! Now it's midnight and I have been reading hacs all night and figured out how to FINALLY get real TPS Percent into data stream!

May have figured how to Hiway AFR?

Don't think there's a way to get actual spark advance... I'm going to bed...

[gregs78cam]

Now it's midnight and I have been reading hacs all night and figured out how to FINALLY get real TPS Percent into data stream!

That's easy, in fact in think this is how I wanted to make it happen and you insisted on using an equation to get %.

TPS VDC --> TPS%, L04F5: 0048 -->0049

Spark Advance shouldn't be hard but it takes up two packets in the datastream, I don't know where to find HIway AFR. The only problem with '7747 is not much datastream to use. Now we could replace the error codes with 3 more datapoints.

This '7747 ADX stuff makes my head hurt. Not much data and nowhere to put what we do have.

[EagleMark]

The C3 160 baud is very limiting compared to newer stuff, that's for sure!

I wanted an ADX anyone could use to get percent without a hac and you helped me achieve that!

Now you helped me (and everyone) learn how to do these hacs with a hard one that needed 2 outputs and 2 inputs and we achieved that!

Then I had enough knowledge to reverse it and found more things to do like a hac for TPS %!

But I want to keep TPS voltage because it is used for min air/idle settings and I found another part of data stream not used to receive data in ADX file, like Prom ID was not there, and worthless for the most part if it were there. It is " 18 OLDPA3 N = COUNTS" I don't even know what it is, but am going to use it for TPS% so I have both TPS% and TPS voltage.

So to summerize...

[RobertISaar]

OLDPA3 (decoded: previous pulse accumulator #3) = knock counter.

and you can always use just the LSB of the spark advance, it's a signed(or is it 2's compliment?) value, so unless you get near firing ATDC often, i wouldn't think its an issue. when bit 7 of the MSB is set, then the SA is displayed in ATDC, with FFFF being 0* or 0.39* ATDC and lower numbers being even further after TDC.

and yeah, once you have control of the datastream, you'll wonder why GM put in some of the stuff that they did.




also, RBob would probably know the actual BPW location in a 7747, no?

[gregs78cam]

AAhhh. You mean here.

                      ;    b2   OF3 A/C          1 = A/C disabled
                      ;    b1   AIR DIVERT       1 = Solenoid engaged
                      ;    b0   AIR SWITCH       1 = Solenoid engaged
                      ;
                    ;---------------------------------
LD507   FDB $0073   ; 17. OLD PA3    KNOCK COUNTER
                    ;      N = COUNTs
                    ;---------------------------------
LD509   FDB $00A3   ; 18. BLM, (BLM/1)
                    ;
                    ;---------------------------------

Can do that too.

[EagleMark]

OLDPA3 (decoded: previous pulse accumulator #3) = knock counter.

and you can always use just the LSB of the spark advance, it's a signed(or is it 2's compliment?) value, so unless you get near firing ATDC often, i wouldn't think its an issue. when bit 7 of the MSB is set, then the SA is displayed in ATDC, with FFFF being 0* or 0.39* ATDC and lower numbers being even further after TDC.

and yeah, once you have control of the datastream, you'll wonder why GM put in some of the stuff that they did.

Thanks Robert I'll look into that when I work on this. Spark advance would be a good feature in ADX but with the XDF and ADX I set up data tracing so I actually know where spark is. It's not a requirment. Injector Duty Cycle/BPW Duty Cyle is not something I can data trace except back to VE to get an idea...

also, RBob would probably know the actual BPW location in a 7747, no?

His knowledge is amazing. He probably knows location from memory... if we fail I'll ask and I'm sure he would help as always. But right now I'm learning so much I just want to run with it for awhile.

[EagleMark]

AAhhh. You mean here.

                      ;    b2   OF3 A/C          1 = A/C disabled
                      ;    b1   AIR DIVERT       1 = Solenoid engaged
                      ;    b0   AIR SWITCH       1 = Solenoid engaged
                      ;
                    ;---------------------------------
LD507   FDB $0073   ; 17. OLD PA3    KNOCK COUNTER
                    ;      N = COUNTs
                    ;---------------------------------
LD509   FDB $00A3   ; 18. BLM, (BLM/1)
                    ;
                    ;---------------------------------

Can do that too.

That's the one! See I am catching on!

[EagleMark]

Yea I get the 160baud, "tune by braille", but the values don't seem anywhere close to what they should be. Do me a favor and tomorrow, try changing the XDF values to "BC0EBC0F", using the attached ADX make a log then change them to "BC3CBC3D" and make another log. Then post back.

I'll try that today while running around. But what address? I don't see those at 0x4E7

[RobertISaar]

he wants you to try the Sync BPW registers directly.... i THINK that will work, but i'm not 100% certain. it works on P4, or at least i remember it working.

[EagleMark]

Ah! I see that earlier in thread. I forgot I don't need that address, I am changing data output address to send differant things!

[EagleMark]

TPS% hac worked first shot! pretty darn close to the calculated value you did off TPS voltage!

OK Greg I did those tests. First I did some changes in my ADX as mentioned above... So I opened your adx and copied the Injector Pulse value over to mine, I am including it so you can check. But first test on both hex strings failed? Got 0 reading on first one and one reading on second one that never changed. Then I changed the Packet offset in ADX from 0x01 to 0x02 and they both worked. One well and the other not so well.

I had a lot of running around to do today and have not looked at them more than just to see they were working and clicking record and saving file. Still busy and will look at them later but posting them up in case you have time between now and then.

You mentioned you may be coming to town Friday, I'll be here all day as the kid has day off and we'll be working on his TBI conversion.