1 Continuous MCPWM at a time

[barneyfrance]

The only problem i'm now having is with my reverse sequence...
I tried with select case and oldstate and it does not work I don't know why

If the only thing controling the sequence of the commutation is the desired direction then there's no reason to keep track of the previous state because then it doesn't matter.

Yep that's what I thought so for the reverse sequence I tried something like this :
If encoderstate = 62 Then
'switches ON/off
endif
IF encoderstate = 63 Then
'switchesON/off
endif
IF encoderstate = 62 Then
'switches on/off
endif


The probem is that the switches (for a same encoder state (62)) should not be the same. When I tried the above code, it is kind of like it's doing the both If..Endif at the same time which is not good.
Any more ideas ?, there's gotta be a way...
Thank you in advance..

[HenrikOlsson]

Hi,
No, I'm sorry, I've misunderstood this. You need to keep track of the old state since 62 are on both sides of 63 there's no way for a simple IF-THEN to determine if the if next commutation "step" should be that equaling encoderstate 60 or 63.

In the forward direction that is not a problem since the same value isn't on both sides of any other value but in reverse it is so you'll have to keep track of the previous state as well.

I must admit though that I still don't understand how this thing work. Let's say the motor is turning forward and then stops at "step" 7, ie EncoderState is 7. It now reverses direction, what is the next expected encoderstate? I don't see 7 in the expected sequence when moving in reverse but it has to be there since, no?

I can't see how the actual numbers can change depending on the direction of rotation. I would guess that if going forward gives you this sequence:

0, 1, 3, 7, 15, 31, 63, 62, 60, 56, 48, 32

the reverse sequence would be:

32, 48, 56, 60, 62, 63, 31, 15, 7, 3, 1, 0

But you're saying it's not. Can you explain, show a diagram or a photo of how this thing works. How can the sensors give out the value 7 in one direction but not in the other? I mean, at that specific rotation angle some sensors are activated and others are not giving the binary value of 7, I can't see how it can be different depending on in which direction the shaft got there.

I'm clearly missing something here but untill I understand how this thing really works there's no use in trying to come up with a solution.

/Henrik.