nAst1: Progress and Concepts Thread

[robertisaar]

ROM:622D                 ldd     word_185        ; MAF frequency in Hz
ROM:6230                 subd    #$5D0           ; make lowest limit of MAF 1 table(1488Hz)
ROM:6233                 bcc     loc_6238        ; 11,216Hz
ROM:6235                 ldd     #0
ROM:6238                 cpd     #$25FF          ; 11,216Hz
ROM:623C                 bls     loc_6241        ; mult LSB by 2
ROM:623E                 ldd     #$25FF          ; cap to 11,216Hz if necessary
ROM:6241                 lsld                    ; mult LSB by 2
ROM:6242                 stab    byte_187        ; LSB of MAF Hz stored here after a doubling
ROM:6245                 tab                     ; move MSB to LSB
ROM:6246                 clra                    ; ignore MSB for now
ROM:6247                 lsld                    ; double LSB again
ROM:6248                 addd    #$241A          ; location of MAF table
ROM:624B                 xgdx                    ; move current location to X
ROM:624C                 pshx                    ; save current location
ROM:624D                 ldd     2,x             ; load value 1 entry rounded up from frequency to D
ROM:624F                 subd    0,x             ; subtract entry from 1 entry rounded down cell
ROM:6251                 pshb                    ; save D
ROM:6252                 psha
ROM:6253                 tsx                     ; point X to stack
ROM:6254                 ldaa    byte_187        ; LSB of MAF Hz stored here after a doubling
ROM:6257                 ldab    1,x             ; LSB of lookup
ROM:6259                 mul                     ; multiply
ROM:625A                 adca    #0              ; add a count to MSB of result if necessary
ROM:625C                 ldab    byte_187        ; LSB of MAF Hz stored here after a doubling
ROM:625F                 psha                    ; save LSB
ROM:6260                 ldaa    0,x             ; MSB of lookup
ROM:6262                 mul                     ; multipy
ROM:6263                 tsx                     ; point X to stack
ROM:6264                 addb    0,x             ; add LSB to D
ROM:6266                 adca    #0              ; round MSB up if necessary
ROM:6268                 ins                     ; restore stack
ROM:6269                 pulx                    ; ...
ROM:626A                 pulx                    ; first PSHX (241A + offset)
ROM:626B                 addd    0,x             ; add 241A + offset to value to make final G/S
ROM:626D                 std     word_18B        ; MAF Grams/Sec value

P6 version.

[robertisaar]

if that's the case, and it always worked correctly, then just swapping out the RPM X 25 variable for the RPM X 50 variable would allow up to 12,750, if you needed to go that high. at that point, then only the output commanding would need to be worked out.

[Superdave]

in regular $A1 i had my shift light turning on at 6375, "RPM ABOVE WHICH SHIFT LIGHT IS ALWAYS ON".. i left the rest of it alone.

[robertisaar]

i have a little bit of EE stuff, but most of it is TC inspired ()

i already have the 96-?? 3x00 MAF converted and interpolated for the table i suggested earlier. i would need a transfer sheet for a LS1 or any other MAF.

i COULD import the code to 2E, wouldn't take more than a few minutes after i start remembering where everything is located.

[SappySE107]

Ill have to PM you but I want EE for a friend of mine down here. He has a 95 Z28 and wants me to tune and it and I don't know what I really need since I have some stuff already.

A single MAF table would be very nice to have, especially if we can convert it to work with a Stock 3400 MAF or an LS1 MAF. If the 94-95 3.4 DOHC MAF code was like that, I would like it a little more. Not now that I don't have access to one though:P

[robertisaar]

are you sure the stock shift light tables would be sufficient? IIRC, they only go to 5000RPM.

i imagine i could impliment a "track only shift light" option that would only be used when near WOT. if you have roughly the same desired shift RPM for every gear change, that would be even simpler to code, since N/V ratios wouldn't need to be setup/checked.

the only problem is finding a suitable output to use. obviously, there would be no reason to use a PWM output for a light.

7727 equivalents: A13, A18 and D2 are the only free outputs in a normal A1 car.


A13 is a digital on/off that is normally unused, only the 90-earlier cars that are converted to $A1 use it for the low coolant light or if F31 trans is selected, shift solenoid B.
A18 is a PWM output, used for AIR divert on manual trans cars or shift solenoid A if F31 trans is selected.
D2 is a digital on/off, Ludis listed it as a relay circuit, no idea why, but it is wired a bit differently than the quad drivers, shouldn't make a difference though.

so, i would recommend D2(A2 on a 7730). i'm not sure how to access it yet though, never looked into that one yet.



side-note: i have the algorithm $EE uses to make a 16 bit grams/sec value from MAF frequency 100% decoded.

[Superdave]

Robert, how hard would it be to change the shift light enable output to a different pin and also have it run when the auto flag is enabled?


I built a badass shift light tonight and i'd like to use it since i've got a kitted auto. 3 luxeon 1 red LED's from a stop light = bright as hell.

[robertisaar]

sidenote: the E-side of the 94-95 LT1 setup is BARE! there is almost 32KB of continuous PROM space that's free.

i was looking around in the LT1 BIN for the subroutine to deal with the lookup, and imagine that, they're not 4 seperate tables in $EE, they're all one continuous table in 128Hz increments. leave it to Tunercat to overcomplicate something. it's a single 16 bit 77 entry table in EE code with EASILY adjustable min and max frequencies of the table, meaning as long as it's an increment of 128Hz, you could go from 0Hz to 65536Hz if the hardware supported it.

from the looks of it, i'll need to modify the algorithm a little bit due to the difference of being native P6 code compared to the P4 we're using(for example XGDX is not allowed on a P4 IIRC, i'll have to do some stack work to replicate it). otherwise, it's simple..... err, relatively speaking.

EXAMPLE:

here is stock 94-95 LT1.

[Superdave]

Dave's not here.

You'd need to compare the front wheel speeds against each other, the rears against each other and then the front against the rear. No matter how you set up the logic for this it's going to be problematic.

http://ww1.microchip.com/downloads/en/AppNotes/00795a.pdf

[robertisaar]

here's a good question: how many "channels" can volt differential amps or frequency comparitors work with? it would be nice to have them all in one circuit, but i imagine if need be, there can be two different comparitor/amp circuits, just pair the sides(one front and one rear wheel), then run the output of the comparitors/amps through an OR gate, and then feed that to the ECM's A/D port?

it would allow all of this to be fed into a single input, which is almost a MUST have at this point in time, though 2 MAY work if necessary, but absolutely no more than that.

[pocket-rocket]

It is, but then I'm also looking at frequency comparators too. I believe this is what I originally had in mind but thought of differential amplifiers as well.

Dave, where are you!?!?

[robertisaar]

hmm....

we're using a low-pass filter to convert a PWM signal to an analog voltage.

is it possible to convert the frequency of the wheel speed sensors into a voltage, which the differential amp can recognize and work with?

[pocket-rocket]

i've only ever heard the term before, but those work off of frequency?

Sadly no. They amplify the difference in two voltages.

A differential amplifier is a type of electronic amplifier that amplifies the difference between two voltages but does not amplify the particular voltages.

http://en.wikipedia.org/wiki/Differential_amplifier

I thought they amplify the difference in frequency before I posted, but they amplify the difference in voltage, apparently. We need to get Dave involved in this It's been far too long for me to remember everything I learned in high school, but I'm willing to give it a shot. In fact, I may just pass on my Black Ops for tonight and go dig my old electronics books out of the garage since somehow I ended up with a pair of the same textbooks I learned from. I'll start in the digital electronics book since that's more of the scope of what we are after. I remember differential amplifiers and such around the same section as the logic gates.

[robertisaar]

i've only ever heard the term before, but those work off of frequency?

[pocket-rocket]

was thinking about the ABS wheel speed sensor based traction control for a while.

i don't know if there is any combination of discrete components that will "compare" the wheel speed sensor's frequencies from the front and rear and create a PWM signal,

Differential amplifiers to compare wheel sensor speeds, then a converter to change it to PWM.