Paul & Sabrina's cheap DIY 144v motor controller

[mora]

Cool. You could drill some holes to the sides of that clear plastic, put leds there and illuminate the logo that way. Should look nice under the hood, especially if it is dark.

[isaac_alaska]

Please please please don't use plexiglas for your enclosure. Use polycarbonate. The difference in strength is orders of magnitude. Plexiglass will shatter just trying to drill it. Polycarbonate is more expensive, but it's essentially indestructible. I used makralon for my enclosure and other boxes. To fasten it together, I drilled and tapped 6-32 holes into the edges and used hex head screws. I'm confident that I could drop my controller from any height and it would survive without a scratch

[bennelson]

No, in this case I was really just using "plexiglass" as a generic term for rigid clear plastic. I know that there are a lot of different types of clear plastics, and I'll need to figure out which one I want to use for the final project.

I'll also have to figure out the thickness for if I really do want to edge-light with LEDs, which I think would be really cool.

[isaac_alaska]

oh okay. scared me for a second there...haha. i used 1/4" and .177 and 1/8 for my case. .177 is thick enough to drill and tap for 6-32 screws if you're reallly careful to get them straight up and down. a mill works great for it..or a good vise on a drill press.

[DJBecker]

Originally Posted by MPaulHolmes

Oh it could be pretty much any pin you want to use. I think Damien's used pin b4 or b5, but I forgot. It would take like 10 seconds to find and replace the pin in the code, so it's no big deal.

Which firmware has tachometer input support? I didn't realise that it had been added.

When we added tachometer code I tried several approaches. I found that using an input capture pin was easiest. The hardware input filter is significant plus when you consider what would otherwise need to be done to work around a slightly noisy input. Requiring a specific type of pin isn't as flexible, but it's worth the limitation.

BTW, the add-on OBD2/CAN reporting code is available from Google Code. It requires a MCP2515 board added to the SPI/programming header. I haven't updated it recently, but it should still link into the Cougar code with a single line change.

[jackbauer]

I have a special version of the code that supports tach input with 2 pulses per rev (4 cyl). Its accurate to about 150rpm and has saved me on many the occasion from an overspeed. The hardware is comprised of a 4v7 zener , 2k2 resistor and a .1uf ceramic on one of the icsp pins (forget which one!). A later code also has brake input in a similar fashion.

[isaac_alaska]

any chance you can get a picture of the different stuff you had to add? i'm guessing the zener diode is placed so the input to the microcontroller never goes higher than the zener voltage? and then the 2.2k resistor would be used as a current limiter into the pin? i think your code would work perfect for my controller, as my speed sensor is already attached to the motor and supplies two pules per revolution. (it's currently being fed to the BMS to display speed and watthours/mile, but i should be able to splice this line to the motor controller no problem)

[DJBecker]

Originally Posted by jackbauer

I have a special version of the code that supports tach input with 2 pulses per rev (4 cyl). Its accurate to about 150rpm and has saved me on many the occasion from an overspeed. The hardware is comprised of a 4v7 zener , 2k2 resistor and a .1uf ceramic on one of the icsp pins (forget which one!). A later code also has brake input in a similar fashion.

Ahh, a "did something screw up" check is less demanding than trying to track RPM accurately enough to report over OBD2 and use for constant-RPM operation (cruise control or PTO/idle mode).

[isaac_alaska]

yeah, that's all i need. something that will limit RPM to less than 7,200. Just enough to keep the motor from blowing itself apart.

[jackbauer]

Yeh that's how the circuit works Isaac. It reports rpm over rs232 along with the normal controller data and rpm limit is also programmable over rs232. Oh and happy St.Patrick's day everyone