This is my fisrst public alpha release of this controller, that can convert a pwm signal (from the output of msns-e) to a signal compatible with a stepper motor.
THE USE OF THIS CIRCUIT (at this stage) IT'S ONLY ADVISED TO WHO KNOW WHAT IS DOING!
Before done a good release (with instructions, pcb layout and other), i need to say how it work, as (at the time of write) it's only bench tested!
I can give support, and of sure, correct bug/problems. I also accept suggestions for made it better (or at least working!
).In the zip there is:
- main.c file. This is the c source code (compiled with HI-TECH PICC compiler). It's very well commented. If you modify this, please leave my name in
- Precompiled hex file for the pic 16f628. This is preconfigured with (possible) reasonable values for gm stepper (Step Time 3.0ms, Step count 170, 100 usable steps for conversion, moving only, 5% threshold in pwm change before taking in account a stepper moviment)
- Schematic circuit... It's not that nice, but if you not understand it, probably is better that you leave this project for now...
- A ICProg Shot for configuring different default values.
If you need different values that de preconfigured, you need to modify the eeprom values before programming the pic:
- The sum of address 0000 + 0001 configure the max steps that your stepper can do.
- The address 0002 is the step time (in 0,1ms - so 30 = 3.0ms)
- The address 0003, if set to 1, configure the always on movment
- The address 0004 is the threshold
- The address 0005 is the delay (in ms) that the stepper wait before move, when you are in manual mode (smaller times allow low resolution, but fastest moviment; higher permit fine changes of the idle, but slowest minimum to maximum)
- The address 0006 is the useful steps that i take in care doing the calcs.
This is here because the pintle, also if not fully open, allow already to pass the flow. This can give at the stepper a smaller range, making it more fast. Remember that a stepper valve, compared to a PWM one, is very slow changing from fully open to fully closed (this wan an original idea of slow_hemi6)
How it work:
First of all, it EXTEND the pintle, for finding the 0 position.
Then it calculate the duty cycle of the pwm signal (with frequency from 50 to 200 hz - 100 is best imho), then moves the stepper proportionally to the duty.
DC at 100% means stepper fully open, DC 0% means stepper fully closed.
For now, it made a linear interpolation, but if necessary i can made a little table.
There are 2 buttons. This are for manual controlling the stepper moviment.
Pressing them together, the led will go on, and you are ready for manual adjustment. Up button increase idle, Down decrease idle.
Pressing the together a second time, the stepper return in auto mode.
REMEMBER THAT THIS IS ONLY AN EXPERIMENT! AND PROBABLY THERE ARE FEW BUGS (i hope not in sw... I've dedicated most of the time at the stability of the code
), SO CHECK, RECHECK AND RECHECK ON MORE TIME BEFORE DONE ANYTHING!I'M NOT RESPONSABLE OF ANY DAMAGE!
Forgot to say, the driver circuit is THE SAME AS MS2, so you can also use a UDN2916, as it's the same as the one as i used.
NEW VERSION AVAIABLE, 3 PAGE, FIRST POST!
, since my car is a daily driver i do not want the worst bugs to happen to me.
