Paul & Sabrina's cheap DIY 144v motor controller

[Roger Heuckeroth]

Matt,

That sounds brilliant! I know nothing about writing code, so my input is worthless when it comes to that.

Are you volunteering to help Paul out with his code? I assume you do this for a living?

Roger

[MPaulHolmes]

That's a good idea about the HAL. I'm going to do that. It reminds me of the good old days of learning to program in DirectX. HAL and HEL! I've been going through to see what needs to be changed, and I don't think there's that much.

So, when I want to send characters by the serial port to SOMETHING, what is the something? What are the settings of that something, like with the even, odd, and no parity, etc... I have no something in the car right now.

[MazdaMatt]

Roger, to be honest, i like to give lots of good programming suggestions, then cop out when the classic line "I'm too busy". Fact is, i just bought a house that i'm totally renovating (lots of new insulation to save on utilities!) and I truely have no time for this. I would LOVE to work on it. I have already scooped a Coldfire board from the scrap heap here at work that I would like to make into a bad-arse control board with all the bells and whistles. I'll write the HAL for that board when the time comes!

Yes, I do this for a living. So it is fun to throw suggestions at Paul and see what he comes up with. So far he's done a great job of transforming his throttle-current control from basement hack to professional hack! (I keed, I keed).

I was actually considering doing an IGBT AC 3-phase board, but I truely can't afford a car project with the new house. I'm thinking maybe I could use Paul's board with lower-voltage parts to run a motorcycle... maybe an end-of-summer project. Who knows how far the code will have come by that time.

[Roger Heuckeroth]

No problem, Matt. I've been there, done that with the house thing. I completely gutted an old country house back in the 90's. I bought the house for the acreage and the view despite the houses condition. Back then I was working full time and traveling about twice a month. It took over 6 months before we were ready to move in. New electric, new plumbing, completely new floor plan all new insulation, etc. It never ends.

Maybe you could just help here and there my looking over Paul's code and telling him what a non-hack would do. We all appreciate your involvement.

[MazdaMatt]

Thanks, Roger. That's basically what I've been doing. I've been keeping an eye on this thread since post #1, i think. And I prefer the term professional-hack, or hackgineer. Even in industry (maybe especially in industry) we don't do things right, we do them fast and under-budget.

As they say in racing - Cheap, Fast, Reliable - choose two! Paul is going for cheap and reliable, which is beautiful for this project, but wouldn't fly in my workplace (we lean to cheap and fast)

[esoneson]

Quote Paul: "So, when I want to send characters by the serial port to SOMETHING, what is the something? What are the settings of that something, like with the even, odd, and no parity, etc... I have no something in the car right now."


RS232 is a very well defined standard that has been in use for decades (literally). What you should do is to pick a set of commonly used parameters that most RS232 based programs use or can easily be configured to (i.e. Hyper Terminal in Windows, Tera Term program in Windows).

The Rx and Tx pins in the atmegaXX need to have their signal modified to fit the stringent requirements of the RS232 standard, that is why the MAX232 chip is there. It might work without it for some RS232 interfaces but we want it to be reliable for all RS232 interfaces. The MAX232 puts the signal within the acceptable range for RS232.

OK, now for the suggested settings:
Data Rate (baud) 19,200 bits per second. Most programs can go up to 56K. I see no need here to go faster and 19.2K can be handled by most all applications. If you think of any that may have trouble at 19.2 then we can always set the default speed (data rate, baud) to 9600 with no serious consequences.
Parity - none
Stop Bits - 1
Flow Control - no

You will be able to connect most any RS232 device to this interface and be very happy with the results. I don't think that we should offer a configurable RS232 interface within the controller at this time, but it is not that big of a deal if it becomes necessary.

Whatever we set the RS232 parameters to in the controller, we have to publish those settings so that the user can set the RS232 parameters at his end to match.

Capiche?

Eric

[esoneson]

Does anyone remember:

Dave Bowman: Hello, HAL do you read me, HAL?
HAL: Affirmative, Dave, I read you.
Dave Bowman: Open the pod bay doors, HAL.
HAL: I'm sorry Dave, I'm afraid I can't do that.


Anyway, I have the Atmel STK500 development kit on order. The board can be populated with atmega8, atmega16, atmega32, etc. So that it would be easy to test and verify a HAL.h for each. When that development kit comes I will be more than happy to abstract the pins for the project for the atmega microprocessors. Not a problem.

Kit has been on order for 5 weeks now. May take a couple more weeks to get here.

Eric

[bennelson]

I just got the controller v1 in the mail.

Wow - Paul really packaged the heck out of it! It showed up in a box the size of a filing cabinet!

I would expect nothing less for his baby.


That said, I am now going to hook it up and go wild!!!!!!!!


Paul, you said to mount it heat sink side down, correct? The way everything is marked seems to imply that.

How close to 12V do I need for powering it? My original 12V car batt is fine right? (12.6V or whatever)

Also, I didn't see a polarity for the throttle wires. I will hook them up, if they don't work, I will swap them. Did we ever put a "high-pedal disable" feature in the software?

Also, do you know how much power the 12V pulls?

[MPaulHolmes]

Yahoo, Ben!!!

The throttle wires don't care. No polarity to worry about. 0 Ohms across them means 0 throttle, and around 5 kOhms across them means full throttle. Just take the 5k pot you are using, and just hook up the 2 wires to the to throttle wires. any darn way you want.

Yes, heat sink side down. It makes less pressure on the solder joints and the JB weld. It probably wouldn't matter, but just to be safe. I have about 5 or 6 square inches of JB weld, so I doubt the heat spreader would break free from the M- bus bar, but just to be safe. Version 2 doesn't have that problem but oh well, you live and you learn. The 12v power supply can be anything in the range of 8v to 18v, so 12.6v is just dandy. And it uses less than 5 watts of power from the 12v supply. I haven't checked exactly how much power it uses. Probably less than 5 watts, but I'm not sure how much less.

There is a tested (and working!) high pedal lockout in the controller. So, feel free to turn the car on with the accelerator all the way to the floor, and nothing will happen. Once your foot comes all the way up to 0 throttle, the high pedal disable will be "disabled" haha! You can drive away at that point.

Or, you could just turn the car on before pressing the accelerator. Either way! It's all good, Yo!

[esoneson]

Calm down, Ben.......don't be nervous. Take it slow, step by step and install that beauty. Double check all connections and do BABY steps at first. We don't want to lose you in the process. Safety first and be smart.

I don't know what deity you are in contact with, but if my hunch is right when you press down on that accelerator, you're likely to utter a few words in reference i.e " OMG!! this smbtch is fast!!"

Good luck.

Eric