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« Last post by Dean Rauch on November 11, 2025, 10:44:13 AM »
Testing out the blade, broke one drive sprocket flange so that has been beefed up. Need some clips to hold the lift rope in the pulleys but otherwise it worked well.
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« Last post by kettenpaul on November 04, 2025, 03:16:19 PM »
Hallo Ich mache gerade ein neues Projekt: https://cults3d.com/de/modell-3d/spiel/1-10-rc-german-sdkfz-9-famo-heavy-artillery-tractorEs soll vielleicht noch ein kleiner Heckkran mit aufgebaut werden und das ganze Model mit TCB gesteuert werden. 3D-Druck mache ich mit Anycubic Kobra S1. Der Druck wird natürlich dauern ,denn es ist ja Modell 1/10. ca. 50 Stunden habe ich schon gedruckt und bin auch schon beim zusammen bauen.
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« Last post by Dean Rauch on October 31, 2025, 09:24:19 PM »
That is an impressive model. Wish I saw that before starting! I didn't think 3d printed shafts could handle the loads in the suspension and gearbox, that model weighs just about the same as my AT-T.
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« Last post by kettenpaul on October 31, 2025, 09:31:16 AM »
hallo Sehr schönes Teil, würde mir auch zusagen. Habe aber gerade was anderes in Arbeit. https://cults3d.com/de/modell-3d/spiel/1-10-rc-german-sdkfz-9-famo-heavy-artillery-tractorBin mit dem Druck voll in Arbeit.Da werde ich wohl einen Ladekran Draufbauen und dann das ganze mit dem TCB steuern.........Mal sehen Den Druck mache ich mit Anycubic Kobra S1 .Als Anfänger im 3D Druck Super Teil ,bin absolut begeistert. Der SDKFZ 9Famo ist ideal für ein FDM Drucker. Und es ist auch sehr viel Bedienung-Hilfe über den Drucker im Netz Zu finden (auf Deutsch)
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« Last post by Dean Rauch on October 30, 2025, 10:47:40 AM »
Prototype is 99% done. Sound smoke and lights are all working.
I will have to get a video soon but for now here it is with a HL Panzer for scale.
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« Last post by LukeZ on October 30, 2025, 08:50:14 AM »
I spent some time last night thinking more about the current sense procedure and I probably had not understood it very well when I wrote my earlier reply. I've looked at the code, the datasheet, and my earlier notes more closely and I've concluded you are doing it correctly, and I also think that the choice of 1.5k for the Rsense resistor is still a good one for the VNH7040. This resistor determines the maximum current we can sense, and you're right, given the ratios for the VNH7040 that comes to about 14 amps. But that is plenty, even if in theory the motor driver says it can do more than that.
But none of that is what you were really commenting on, I just got sidetracked. You were mentioning the fact that sometimes the Multi Sense pin goes to saturation, indicating an error condition; but you knew you weren't drawing anything near 14 amps. I agree with you, this is not likely a real error, but rather a transient condition. I would suggest that instead of checking for a fault condition every single time through the main loop, which will detect even the briefest of transients, that instead you look at how we are measuring currents and copy that approach for checking the fault conditions. Firstly, we only measure currents at some predetermined frequency (CurrentReadFrequency_mS which we set to 100 milliseconds). And even though we read currents ten times a second, we don't throw an overcurrent error until we have 10 consecutive readings over the limit (so in total the overcurrent condition will have to last persistently for 1 second for us to consider it valid).
You can adjust the actual frequency and count of consecutive fault indicators to whatever makes the most sense in your testing, but the idea is that this lets you weed out "false positives" or temporary spikes that are not actually relevant or persistent.
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« Last post by LukeZ on October 29, 2025, 03:05:45 PM »
Hi Neil,
Ok, I can see your GitLab project now, but only when I'm logged in. That's fine for me, but it would be good if you could set it to be visible to everyone, whether they have an account or not.
I've spent some time again beating my head against the wall with the VNH7040 datasheet. In terms of current sensing, it looks like it uses the exact same process as the VNH5019, only with different constants. What is so confusing is on page 16 of the datasheet they give the same Vsense of 0.5v for two current levels (Iout 0.05A and 0.3A), and again the same Vsense of 4v for the three remaining levels (Iout of 3A, 5A, and 10A). This should not be possible. The sense voltage (current across the sensing resistor) should change as the current changes.
Of course it would be nice if they'd tell us what resistor value they're using for their measurements, but we can deduce it. On the VNH5019, the implied resistor value was fairly consistent across all their readings, it came to about 1.1k. I can't remember now why I chose 1.5k.
But with the examples we have from the VNH7040 datasheet, if they can even be trusted, which I'm not convinced they can, the implied Rsense resistor value ranges all over the place. Of course, we can only have one value on our board (these are R115 and R116 on your schematic).
Anyway, when you're calculating 14.3A, all that means is that the voltage over the Rsense resistor has saturated - and probably, since you don't think you were drawing 14.3 amps in real life, it saturated much earlier.
I think really the best way to understand what is going on would be to take some actual measurements of current draw and simultaneously the voltage at point M1_MS (or M2_MS) on your schematic, and get some empirical evidence of what the ratios are.
A few more comments:
In your code, you might want to set motor state to MOTOR_STOPPED in these two function. Otherwise the state will still show as ROTATING even when stopped, and the current sense measurements will still occur. However I don't think this actually would cause any problems, but I thought I'd mention it anyway.
void StopMotor1(void)
{
M1_Speed = 0;
M1_OCR = 0;
if (BrakeAtStop) BrakeMotor1();
else Motor1State = MOTOR_STOPPED; // ADD THIS LINE
}
void StopMotor2(void)
{
M2_Speed = 0;
M2_OCR = 0;
if (BrakeAtStop) BrakeMotor2();
else Motor2State = MOTOR_STOPPED; // ADD THIS LINE
}
Finally, I should have told you this a year and a half ago, but the reason I put ADC7 to +5v, is so that if someday a different hardware version was made, that new version could set it to Gnd, and then the firmware could read that status of that pin on boot, and adjust the code to fit the hardware. This would let us have a single firmware for both boards, instead of two. Of course there was no way you could have known that, and it's not a problem to have two distinct firmwares. But if you ever have to redesign the board for some other reason (God forbid), you could make that change.
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« Last post by NielsD on October 27, 2025, 02:08:26 PM »
Thanks again!  Als thanks for thinking along on the heatsinks. I ordered some of the 9x9x12 heatsinks, with which I have enough height to clear the capacitors. I also granted you access to the Gitlab project, so please check if it works. One quirk with the Multisense output is that it seems to saturate to maximum ADC value so now and then. It doesn’t stay in that error for long, so I think it is not a real error that is triggered. On the other hand, I also don’t expect it to draw 14.3A (which should be 14 [mA/count] multiplied by 1023 [counts]). This is something I have to do some measurements on to solve I guess.
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« Last post by LukeZ on October 27, 2025, 09:24:24 AM »
Congrats on validating your design! I had no doubt it would work but it's nice to see it moving something in the real world. Congratulations also on sticking to the project over the long term. It's easy to start a project; hard to finish.
The tallest 10x10 heatsinks that I have seen are 10mm tall (ie, it's a 10mm cube). I'm sure you've seen those. The only thing taller that appears to be close in size is 9x9x12, if you search for that on Amazon or AliExpress you'll find them easily.
Since you don't have caps in-between your two chips like I did, maybe you could use a single wide heatsink that would attach to both. I am seeing 22x8x7 and 22x13x11 on AliExpress. I don't know if 22mm is quite long enough, and you don't gain anything in height, but you would get more surface area.
I tried looking at your project on GitLab but although I can navigate to the page you linked, the code is not visible. Maybe it needs to be made public somehow, but at any rate it would be good if anyone could view it without having a GitLab account.
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« Last post by NielsD on October 26, 2025, 10:25:32 AM »
I implemented the Multisense functionality and uploaded the code here: https://gitlab.com/niels.d/scout-miniThe readme still needs some updating and also the board files need to be uploaded (but they are on another laptop and I have to clean them up a bit). I am also looking for heatsinks, but couldn't find any suitable ones in 10x10mm and enough height to protrude above the capacitors (which are a bit of an airflow obstruction unfortunately). Maybe someone here has a tip for where to get those?
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