MoTeC Global Forum

Hi MoTeC

any time line of when the update for the MoTeC PDM32 is coming out and specifically, PWM. Is it going to be configurable for

Frequency (60hz-1khz for example)
Duty Cycle (10% - 100% for example).

figgie,


PWM is not going happen for the PDM as it currently is. Thats the anwer i got. The best you could do is a flasher of 0.02s on and 0.02s off that will give you 25Hz 50% duty sincel all calcs in the PDM is done at 50Hz. Maybe try differnt on and aff times to cary the dyty cycle but you scarifice Frequency that way. expample is you double the on time you will get 66.6% duty but only a third of the freq (about 17Hz)

Maybe somebody at motec knows of something down the pipeline?

Martin Roets

Hi martin

well it really is not taht huge a deal.

I have a PWM circuit that I use for High current driving but this was more for along the thoughts of driving LED's array for brakes lights etc that require a minimum of 60 hz and I usually run them at 200hz+ base frequency

I Find it odd that they can not dedicate 1 or two outputs to true PWM (freq and Duty Cycle). Oh well!

why would you like to dive a brake light LED array at freq? I understand that you`d maybe want to vary the brightness and not have the flickering visible in a shift light LED array. But the brakelight?

Martin

yes the brake lights. In my car. The brake lights serve as tail lights also. So you have the dim output at night and then 100% brightness. Hence the want for PWM, run the tailights at 50% and then turn them to 100% on brake application. if the PDM did PWM based on input that would be killer but perhaps the Ole Buhl Racing PDM is the only option aside from my PWM circuit

Would a capacitor be useful in reducing flickering if you Flash the output at 25 Hz 50%?

Then if you want to turn the Brake LTS on make the output turn on permanently. Think this could work?

Well, like I said . I already have my PWM circuit that i use for LED before. So since I already have the parts. that is what I will use.

Hi Figgie,
The PDM was never designed to do full control of devices but to supply protected and switched power only. In fact it can do a lot more than was ever intended already!
It is possible for the PDM to do some basic PWM for low current devices and your tail/brake light control is a good example of a possibility.
We are looking into implementing some form of PWM function by function, and we are interested in users ideas of what they would like to drive and how.

Darren

thanks so much! I know of the PDM32 capabilities as I am installing one as we speak

Well, PWM for low current device would be a nice addition as then you can drive an array of led for brake lights (both tail lights in headlight mode on and then bright in brake mode), turn signals, and even backup lights incase the array is too bright (such a thing if you are blinding the drivers behind you). Of course if it is not feasible. and add on module perhaps

If anything a fixed base frequency greater than 100hz would be absolutely fine for LED driving (minimize flicker that a person will see by alot save for the few that can still see it). Duty cycle will still need some adjustment (20%-80% will be quite suitable for LED array driving) or logic to choose between two

ie

Output.Lights.Brake =
input.lights.brake = true for .002 and
pulse (pwm?) 80% DutyCycle

Output.Lights.Headlight=
input.lights.Headlights = true for .002
pulse = 30% DutyCycle

something to that effect if it can be done that is

Hi,
Regarding PWM applications.... We have worked around the following in recent years using a solid state relays and controlled by an ADL output. It would be great to remove such items and go directly through the PDM.
>Engine Fan
>Aircon Clutch (0-100% pwm @ 400Hz)
>High pressure fuel pump

Cheers.