bradsm87
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Posts posted by bradsm87
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1 hour ago, Adamw said:
Yeah, I think would be good to have a GP boolean on/off table too. Its been asked for a few times in the past, specifically for VTC. I will get it on the wish list to consider.
You can just use a GP PWM but you have to choose your axis breakpoints carefully. For instance if you want one switch point at 4000RPM, you need a column at 3999 and a column at 4000 to get rid of the interpolation.
Yes boolean on/off would be excellent. I've played with 3d tables with RPM axis of 999, 1000, 1999, 2000, 4299 and 4300. I need VTC on at 2000rpm at low load but on at 1000rpm at high load with effectively a straight line in between. I thought this would be really easy to do in a 3d map but it actually seems tricky to do with the playing around I've done.
1 hour ago, Vaughan said:Fair, you could give it very sharp cutoffs by playing with your axes or you could possibly use a math block instead of the gp pwm as it looks like it would be a reasonably simple equation.
Interesting concept. Yes math block could be a winner to get the different cutoff at varying load. I'll have a play with that option. Thanks.
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47 minutes ago, Vaughan said:
Why not just use the gp pwm output directly with either 0 or 100% Duty Cycle?
Because it will still interpolate between cells and use duty cycles in between.
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I've been playing around with the Storm sample file and can't seem to find a nice way to set up a 3d table or something else that can let me control an output's on or off state dependent on both load and RPM without at least wasting a GP PWM output that won't be physically used. I need to control Nissan on/off VTC control and be able to customise the switch points based on both RPM and load. I have attached a screenshot from another ECU's approach to achieving this.
The only way I've found so far seems a bit messy but workable. If I enable a GP PWM output, set up the 3d table with values of 0 for off and 100 for on, not use that physical pin at all, enable another normal GP output, set the condition for that one to be on if the previously set up GP PWM is above 50%, put some other conditions in if needed and use that one as the VTC solenoid output. Is this the way to go or is there a better way?
I know Virtual GP PWM outputs are coming. This will be great because I don't know if I'll have a spare pin to assign a GP PWM to that won't be physically used anyway.
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21 minutes ago, dx4picco said:
I would configure Virtual aux outputs to be triggered on a given voltage level. and then trigger your "completely different thing" with the corepsonding virtual aux.
Excellent. Yes that's the nicest option. Looks like math block would work too but virtual aux is way nicer. Thanks!
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If I have 4 different steering wheel buttons that share 2 wires and want to use those 4 buttons for 4 completely different things, what is the best way to do that? From what I can see, the only way is to play with pull-up resistor values until the voltage values fall into the right places to use a "GP rotary switch" input. Even if I had use a higher number of positions in the GP rotary switch and skip some GP rotary switch positions, as long the same button hits the same switch position output every time, it wouldn't matter. Is that the way to go?
Edit: Actually the above may not be very useful as I can't select a particular GP rotary switch position as an option when choosing an input for launch control activation control for example. Any other ideas? Would a GP analogue volt and 4 different math blocks outputting 0 or 1 depending on whether or not the analogue voltage is within a specified range in each math block work?
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4 hours ago, Adamw said:
I chased engineering last night to get a feel for what the delay was. Most of the other G4X's ECU's we had quite a large stock of prior to all the covid stuff, but the Fury was just entering production at the start of it all. The long shut down of most of the major electronics manufactures (mostly China) and the consequent stockpiling that many of the large manufacturers done has caused worldwide extinction of several needed electronic components and a massive backlog for the component producers. At the moment we are waiting in the cue like everyone else with no firm ETA sorry.
No worries Adam and thanks for the update. I'm definitely excited for the G4X and what is still to come for it. I'll leave the ECU purchase right up until the car is nearly ready for first start and go from there. I may consider an Xtreme and CAN Lambda when the time comes.
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I think I'll just wait a bit longer. I had a good play with the Emtron and although more flexible in many ways, some of the things I want are easier done on the Link. I have confidence that with the new faster G4X hardware, that more new features will continue to come. The extra pairs of half bridge drivers I feel make the Emtron a little more future proof for things like electronic wastegates but cost is obviously a factor too.
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1 hour ago, Electredge said:
If you want the new X-series I'd do the Xtreme and use a separate WB controller (CAN or Analog) what kind of car? whats it being used for?
I like the simplicity of having it all in one box. It'll be for a Nissan Patrol TB48DE turbo used for a bit of everything.
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I called Link on Thursday to get an ETA for the Fury and didn't get a call back. Now looking into the option of forking out the extra for an Emtron KV8.
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4 hours ago, AshB said:
Do you have any recommendations for what I should look for, specific makes/models etc. Don't mind spending a bit more for something that has decent performance and will allow me to do this
I've used a few different brands of the Chinese ones and Dasaita seem to have actual existent support and updates. I've been happy with my last two Dasaitas. Get one with the PX6 processor.
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I like the idea of air per cyl estimated as the axis. I think I'll try that first.
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Wouldn't it be best to put a load axis on the update rate table as well and increase update rate with higher load for same RPM as well?
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I went for this adaptor which is one of the RealDash recommended ones (with AliExpress premium shipping).
https://www.aliexpress.com/item/4000925486786.html
Yep stuff out of China takes forever at the moment. I've had dramas trying to get things and even paying big bucks for fast shipping for stuff since March and nothing.
@AshB long story short is you need to configure your CAN streams on the Link then create an XML for RealDash CAN and use a RealDash CAN supported CAN adaptor.
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I ordered a Circuit 7 4-port solenoid with a wider usable duty cycle range than the off-the-shelf 4-port Mac solenoid so that should be a good place to start and that's what I'll try first. I'll chuck another wire in the loom to keep the option of running 2x 3-ports just in case.
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On 5/23/2020 at 9:21 AM, Adamw said:
That's why Im suggesting it is a bad idea to do it with a hold and decay. Every time you press the button a new offset would get added on top of the last one that is still active/decaying. So your RPM will get higher and higher everytime you press the button.
So that side effect couldn't be programmed out? If something is decaying back to normal and the switch is re-introduced, I'd hope the decay can be removed the moment the offset is applied again. I can't think of any scenarios where someone would want it to build up like that in any application.
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4 hours ago, Stevieturbo said:
But really...a 3 port can do the same job anyway, been doing it on mine for years.
Really? 15psi with a 3psi wastegate spring as I mentioned?
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1 hour ago, Adamw said:
Try it first and let us know if it doesnt work as is. Typically for a load related idle up you dont want a hold/decay as if the load gets activated again while it is still decaying from the last activation then the offsets accumulate and you end up pushing the idle higher and higher so the closed loop system will get integral wind up trying to pull it back to target. There is a new feature coming out soon (I think it is in the next release) which adds a delay on and delay off timer to digital inputs and aux outputs, so I suspect that will take care of it turning on/off too often.
The load side of things will be mapped correctly as a battery volt axis on the idle base position table so PID should hopefully not need to make large changes away from that. The hold and decay request is more for the switched GP idle rpm offset. I really don't want my idle jumping around all over the place every couple of seconds. Nice slow decay would be better because there will be a very good chance that the switch will be re-applied within a second or two. I would try but waiting for the G4X Fury. There would be two things at play, first being the winch activation switch (and it's not always under load) which would be the GP idle rpm offset (say +800rpm offset) and second being the gradual idle target increase with battery voltage reduction as the winch sees more load. Not having a delay and decay with the load side of things is fine. It's just the GP idle offset switch that would be great to have delay and decay on.
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1 hour ago, Adamw said:
Under Idle actuator settings there is a GP Idle source, setting this to your winch DI will enable an offset to the idle valve position and an offset to the idle target if in closed loop. If you want to take care of battery voltage you can make your main target and base position tables 3D with batt volatge on the Y axis.
OK yes I think I can work with that. Might come in handy for general high current draw scenarios with lights etc causing voltage to drop too. Thanks.
Would it be possible to get a hold time and decay time for GP idle up? If I'm hitting the winch switch on and off quite a lot, I don't want the idle jumping around. A 15 second hold would fix that.
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First impressions playing with the G4X Storm base map file are that these don't quite have the flexibility that I had hoped for or maybe I'm just not looking properly.
I need a switched GP idle table where I can use a 3d map. I thought I could just use the "AC Offset Table" function but that's a fixed single row table and the axis setup option is greyed out and axis forced to coolant temp.
I want to use the winch trigger wire into a DI input and use it to enabled a switched idle target table. An idle target table for coolant temp x battery volts would be fine OR an idle offset table with battery volts as the axis would be OK too. Enabling the ability to change the axis on the AC offset table would be enough. That way, hitting the winch switch with light load can give me a moderately higher idle to start with but when the winch load increases and battery voltage drops, I want the idle speed to come up further.
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41 minutes ago, Stevieturbo said:
And can easily be done with a 3 port too....
It's not rocket science. But the first question is.....do you even need this mode of control ? What issues are you having that you feel the need to do it this way ?
But a 4 port solenoid should work too, they just respond a bit slower than a 3 port.
The reason I bring it up is I want to purchase things and wire up the car once and right the first time. I've heard way more horror stories about 4-bort boost control being way too touchy than good stories. I'd like accurate boost control anywhere from the 3psi wastegate pressure up to 15psi. I thought using a traditional setup to control the bottom of the actuator only for finer control over the lower targets then only gradually bring a little in to the top port when needed would be the best way to achieve this.
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5 hours ago, Adamw said:
It will need to be a bit more sophisticated than your picture above but the control system you describe is what some higher end systems call phase/anti-phase wastegate control. In theory if you put the time in to linearise the system properly then yes you could potentially get a wide range pressure control that was more linear than a 4 port or two 3 ports just plumbed in reverse NO/NC. These higher end systems actually even go a bit further and have deadtime and battery voltage correction curves for the solenoids to get it as linear as possible.
However, in practice in the few maps I have seen set up this way from fairly high end WRC cars, the solenoids were just set up to work in exact inverse of each other - i.e. exactly the same as how a single 4 port would do it...
My main concern is that the 4-port is widely seen as extremely touchy and doesn't work well for boost targets close to wastegate pressure (targets I intend to use for accelerator positions around 60%). Many say it doesn't come into a good usable range until you're at least double the wastegate pressure. If I keep the top port completely out of the equation at lower boost targets, I thought operating staged solenoids would fix this, only having the secondary (top port) solenoid slightly come in gradually as WOT boost target approaches.
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So I finally have an understanding of how 4-port boost solenoids work and their wonderful ability of being able to direct boost to either the top or bottom port on the wastegate.
I started reading into what they are like to tune and there is WAY more negative than positive. Most say that they're way too touchy when trying to control boost accurately. It seems many try then go back to a 3-port setup.
What about run it like this:
One 3-port solenoid to each of the top and bottom ports. The top one is at 100% dc by default, letting the top port stay at ambient pressure by default. The bottom one operates like a traditional 3-port solenoid setup. Run them staggered. For low boost targets, you use the traditional boost control setup and top solenoid remains at 100% dc. You set up a GP PWM output to drive the secondary (top) solenoid with the output of the first boost solenoid as the axis. You then map out the high boost boost target zone that the traditional arrangement can't maintain due to EMAP pushing the valve open (the areas where high DC on the primary boost control solenoid are used) and gradually reduce duty cycle on the top solenoid as primary boost solenoid duty cycle increases to let some boost into the top of the wastegate.
Even if you just use a small range of top solenoid duty cycle right at the top of the range of the primary solenoid where its operation is no longer linear, just to get a bit more range out of it, I think it could work really well.
I'm very tempted to order another 3-port solenoid and try this. That way you get the fine control that the 3-port setup is best for but can add some boost to the top port only when needed.
Better yet (safer) would be to find a secondary solenoid that operates in the reverse manner as the usual ones so that it is closed by default and keeping the top port vented by default in case it gets unplugged or something.
I attached a pic of the secondary (top) solenoid GP PWM DC table. Primary boost solenoid DC is the axis. It does nothing until 50% WGDC then gradually comes in after that.
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55 minutes ago, Adamw said:
It can be done in the G4X presently with GP PWM's (still need to assign an ouput pin at present tho) and will likely get some sort of "PWM virtual aux" functionality added soon. Unfortunately unlikely in G4+ due to constraints in the firmware.
Thanks. If you could add PWM virtual aux or similar to the G4X to-do list, that would be great. Some stuff would be handy to have more control than just 2 axes and another 3d table would do the job very nicely!
Generic 3d table for switched output
in G4x
Posted
OK here is a challenge! I'm not sure that a math block can do this but maybe I just can't get my head around how to do it. Here is an excel formula that does exactly what I need for the lower VTC threshold, that is, 2000rpm up to 40kpa with the RPM threshold gradually decreasing to 1000rpm at 80kpa then staying at 1000rpm at higher than 80kpa. The excel formula works as I would want the math block to work.