Paul & Sabrina's cheap DIY 144v motor controller - Page 672 - Fuel Economy, Hypermiling, EcoModding News and Forum

flores · 07-20-2014, 02:46 PM

I have a Rigol 1074Z.. I think that can be powered from a battery.. I'll have to see.

Do I really need to drive? I can measure anything with the wheels in the air on the car lift.

flores · 07-20-2014, 02:47 PM

Note to self: Trying to reprogram the micro but pickit fails to connect all the time? disconnect the dc-dc connection and it works.

MPaulHolmes · 07-20-2014, 02:58 PM

The wheels lifted up would be fine. Any current is good. Then, the turnoff spike is proportional to the current. Weird about the dc-dc.

z_power · 07-20-2014, 03:30 PM

Quote:

Originally Posted by flores

Do I really need to drive? I can measure anything with the wheels in the air on the car lift.

With wheels lifted and parking brake in good condition you can add some braking action to see higher amp levels, at least for some short time. On fourth gear should be easy to see some hundreds of amps for a few seconds needed to "shot" a sample. Just keep an eye on motor and controller temperatures

flores · 07-20-2014, 03:41 PM

I'm trying to get that rs232 shield working but fail miserably.. I don't get it.. it's just a simple max232

flores · 07-20-2014, 04:09 PM

Its weird..

If I connect the controller with real term with an usb-rs232 cable, I see the rtd data.. so the output of data from the controller works.

If I connect the shield to the usb-rs232 cable and connect rx and tx on ttl level on the shield the data is echoed.. so the shield is good.

But if I connect the shield to the controller nothing works.. no data on the outputs and led's don't flash up..

I don't get it.. anybody an idea?

Maybe the controllers rs232 levels aren't sufficient for the shield but are for the usb-rs232 cable?

MPaulHolmes · 07-20-2014, 04:47 PM

The DC-DC has a male spade connector for grounding it. I didn't use that. I don't know if that would help with anything. Also, maybe the control board ground should be grounded?

flores · 07-20-2014, 05:05 PM

Ah of course.. the dc-dc isolates things.. you maybe on to something.

Will test that tomorrow..

Astro · 07-20-2014, 08:20 PM

Quote:

Originally Posted by flores

Note to self: Trying to reprogram the micro but pickit fails to connect all the time? disconnect the dc-dc connection and it works.

Is this with the DC-DC powered or just connected?

When i have programmed pics in circuit it was always on a un-powered circuit with the pickit supplying the power.
I haven't tried it with the target circuit being powered and setting the pickit to not supply power.

The pickit is only capable of supplying a limited amount of current to the circuit when it is powering the circuit (depends on USB port power output i think). If you are supplying power from the pickit then maybe the un-powered DC-DC is loading the pickit beyond its current capacity?

Does the programming interface throw any errors?
I use the Linux version of the MPLAB programmer and it tells me when the target circuit is trying to take too much power from the pickit.

BTW How cool is it to be able to connect a pickit and upload new software that can totally change the abilities of the target circuit. When i first started messing about with electronics (30 years ago, yeah people say i'm getting old, i don't believe them) even the smallest change in the way a circuit needed to function required a re-design and re-build of the circuit. It really is fun to make a software change and upload it and see the circuit magically work in a totally new way.

jedsmd · 07-21-2014, 12:14 AM

Quote:

Originally Posted by Astro

Is this with the DC-DC powered or just connected?

When i have programmed pics in circuit it was always on a un-powered circuit with the pickit supplying the power.
I haven't tried it with the target circuit being powered and setting the pickit to not supply power.

The pickit is only capable of supplying a limited amount of current to the circuit when it is powering the circuit (depends on USB port power output i think). If you are supplying power from the pickit then maybe the un-powered DC-DC is loading the pickit beyond its current capacity?
....

Interesting
When I load the program, with the controller in the truck, using the Pickit 3, Mplab cannot see the chip unless the controller power is on. I just thought that was the way you were supposed to do it.