mikey

Yep, you got it. Dashboard Restos, Steve is a really nice chap. Real good to deal with.

Dashboard is recovered and looking super! Before: After: Latest pic of the car, 50% in primer, many new patches, no filler yet.

Awesome work!

YEAHYA! Awesome.

Yeah, if we can get an ESC to run slow enough and at fixed speeds then I'll go that way. But at the moment it's looking easier to rip the guts out of the speedo and hook a stepper up to the needle. I can hook another stepper up to the odometer. Just seems easier to me now? I'm reaching the limit of my know-how with driving the BLDC from the PIC I think, even with the L239D motor driver.

It must be possible to get ESC's that work with precise speeds, otherwise RC helicopters would be shit. Edit: Yeah, looks like a lot of ESC's allow you program them in constant speed mode. Which is probably what I need to do. Ned, any idea what model ESC this is? Or of that open source ESC code supports constant speed mode?

Yeah, maybe, it's worth a shot. I'll try and give it a go tomorrow.

The ESC does some sensing of the supply voltage and beeps warnings when it's too low. Not sure where that cut off is but it wont run as low as 5v. I don't have a proper adjustable power supply unfortunately. The motor control chip I have has all the H-bridges I need, but I'm just not sure if PWM modulating the motor in open loop will work and it sounds like a truck load of work.... Modifying the AVR code would be great. But I'm just a little unsure if it'll work... If we slow down the motor too much I'm guessing it wont induce enough current in the unpowered coil to sense the correct timing and work in closed loop. Open loop seems to make more sense to me than closed loop anyhow, as we want to run at a set speed so we dont care about the optimal timing. However to avoid overstepping I have to PWM the coils as well as adjust the timing I switch them on and off. And at this point my brain hurts....

The same problem being non-constant speed when under load?

Hey Ned, what make/model is that ESC? There's no marking on it. Some dont go below 30% duty, I wonder if this is one of them.

To achieve slow enough speeds? I can drive the motor with the motor driver chip I was using for the stepper I had before. If I dont wanna run full speed though I have to PWM each coil as I go. Probably not a major problem. There's even open source ESC code for PIC's I can use. But, would running a lower KV motor be enough to slow things down without all the bother? One issue with the ESC is I _think_ they detect speed by reading the unused coil while they charge the other two. So that explains why it's susceptible to load but doesn't end out skipping steps. This is all just a theory / what I've pieced together today by reading / I know fuck all about these motors.

This is a video of it running at the slowest speed the controller will run at: There's a couple of problems, that speed is far to fast, but also depending on how much load I put on the motor the speed jumps around quiet a bit. During that vid I'm changing how much weight I put on the motor which has a big effect on speed. Time will tell if this will be an issue or not. I need to organise a proper connection between the motor and speedo and see how it goes.

Less throttle was the answer, I was giving it a duty of 50% which is waaaay over 100% throttle, dropped it down and now working. Just tryiing to get some consistant slow speeds now.

Yeah, there's no speed sensor anywhere currently, so no signal to convert unfortunately. I've got this BLDC motor almost working. It's talking to the ESC and I have a button which effectively goes from full throttle to zero throttle. Problem is when I go full throttle it cuts-out after about half a second. I think it has something to do with the modulating signal changing slightly and the ESC cuts-out. I'll keep playing. http://s1230.photobucket.com/user/mmcl055/media/VID_20130721_174146.mp4.html

Servo would be great except you lose you odometer and also I have nothing to attach the other end of the servo to.

You're right, I will enjoy life a lot more if I just use an ESC. I'll do that. Ned's gonna lend me one to play with. I'm not using an arduino BTW, just gonna stick with the PIC.

No, I dont want to be Mr fancy pants at all. Just being impatient Can I grab one today?

Yeah, looks like most people drive them as three phase but using PWM, which sounds like a ballache but once I get into it I'm sure it wont be too hard. Fuck it, I'm gonna go get one.

Hmmm, not really in junkyard mode. I'm tempted to go and buy one of these: http://rcb.shopnz.biz/catalog/product_info.php?cPath=51_77_28417&products_id=2493&osCsid=1cc0ef2a6fa7b82d2ed81605ed64d76a Only concern is the control for them. I've not been able to find definitely how I'm supposed to controll it given the three wires. I suspect it's just like a three phase motor and I just alternate through the three wires with my motor controller. But it's just a guess...

Maybe I should grab a motor from a CPU cooling fan instead? They're a lot easier to get your hands on.

Circuit and code is all working. Just need to get a BLDC motor that can do around 4,000RPM. Also, a lot of those BLDC's from remote controlled cars are three wire. How does that work?

You're well overdue for a fang! Probably wont be fangable for a couple o' months yet unfortunately. My speedo doesn't have to be this much work, but I'm determined to use the original gauges!

Definitely keen on a hand, as you know my electronics is pretty basic. First step is to just get the motor turning. Then see what speed I can get it to do and whether it's fast enough for the speedo. But from what you've said it probably wont be. But that driver chip I'm using can drive a range of motors. So I guess I'll need to track down a 12v BLDC which can spin at around 4,000 RPM. I had a quick google today and couldn't find much locally. I've already written some code for sensing the hall sensor input and recording the timing.

I did this today: It's a PIC16F628 with a L293D motor driver. I've hooked up a hall sensor and stepper motor. If the motor's not fast enough I'll find another brushless motor that is. Tomorrow I'll write some code and hopefully hook it up to the speedo.

Success at last! The one on the left was the kind I really wanted, this one is from a Mazda V6 crank sensor. The one on the right is from a Mitsubishi Cam position sensor.