dual PWM test
September 6, 2008
Alright, so I'm just dabling with this stuff, but thought I'd see if I could create a small circuit that could split a pwm signal from a 08m/14m micro into a dual pwm output "for fine control of two motors". I wanted to control the output for each of the two channels even if the same pwm sig would be going to them, at least I could select which channel or channels would be on
This is the image of what it looks like. It has some fine tuning and I'll see about getting a schematic(thats not on a piece of paper).
It has a direct pwm input signal coming from the blue wire.
The red and yellow(the one on the right) wires are inputs that go high for each individual motor.
The black wire is used for testing of the led lights.
The yellow wire is an output wire that I was using to finetune the voltage.
The second output(where it says me) was what I was using for the base voltage since it was lower.
The transistors are mps2222A npn's from radioshack, pretty cheap.
The pwm output I tested showed 1.12 to 4.85 volts with a +/- 0.02 volts variance between the two channels.not too bad, but we'll see how it affects the control....
The yellow wire was used for some fine tuning/testing due to voltages being slightly off. The pot is used as a voltage splitter which allows for a finer control of the output voltages. I'll have to work on a better design that integrates the trim pots since as it is, this setup requires it . I'll figure something out later.
Testing of the setup at least from the outputs looks good. I need to get a motor driver to test how it will work with a dual motor setup.
I'm testing this with an 08m but this is meant to be used with a 14m as it has the 4 outputs, pwm out and a serial input that would be required for this to fully function(having variable speed reverse as well.).
So far this uses pins 1 and 4 for the channels switches and pin 2 for the pwm out signal. Pin 3 is slotted for serial input...though I recall some issue with it and serial com...I'll have to read up on it.
Let me know what ya folks think, good/bad, improvments...all that fun stuff.