Stepper Motor with 16F877A

[hayate_kun]

Hello!

Can anyone give me some example of motor stepper coding with 16F877A? Thank you.

I'm using LINIX 6.0kg.cm Stepping Motor.

[Ttelmah]

You already have an example of basic stepper control. EX_STEP.C.

99%, depends on how 'well' you actually want to drive the motor, and what speeds you want to achieve. The simplest stepper control just has transistors driving the phases from their rated voltage, and is limited to a few hundred steps per second. The problem is that the phases are massively inductive, and simple electronic theory, tells you that when you apply voltage to an inductor, the current takes time to rise. So step fast, the current goes down, and the power output of the motor declines. The solution, is to realise that the voltage 'rating' of a stepper is the continuous voltage that can be applied 'stationary', and not overheat the motor. When moving, you can massively increase the end point voltage, so long as the current doesn't rise above the motor rating. It is typical to operate a '6v' stepper, off something like a 50v supply, if you want to move the motor fast, but then you _must_ have software or hardware to limit the maximum current through the coils to the motor rating. Control at this more sophisticated level, can be done directly by some PICs (particularly those with the power PWM module, and a comparator Using the latter to control the PWM being fed to the motor phases. However with the 16F877, all you are really going to be able to do is send pulses to turn on the phases, and if you want more sophistication, you will have to provide this in your driver hardware (there are many dozens of standard chips that automatically generate the PWM signals for you).

Best Wishes

[hayate_kun]

Hi, thank you for your reply.

I've moved the stepper motor using PWM, however my lecturer told me that is actually incorrect way to move the stepper motor.

This is my code (freq setting=145, pwm=120, delay=700ms) it will move 9 deg per step, thus takes 40 steps per revolution:

[arunb]

what driver are you using ?? Please post a link to the datasheet.. also what kind of a stepper motor are you using ?

thanks
a

[hayate_kun]

I'm using LINIX stepping motor: model 57BYGHD451
with driver: SJ-230M2 / 5 phase hybrid stepper motor

Here's the link of driver's datasheet:
http://www.filedropper.com/stepper60kgcmdriverlatestfromcytron

[Ttelmah]

Start with a simple statement. You don't want a stepper driver.....

You already _have_ a stepper driver. The unit you are using already generates the PWM to 'drive' the motor. This is why your instructor is pointing you away from PWM. You _can_ develop the pulse train needed by this controller using PWM, but you should start simpler. Also, there are reasons why this may _not_ be the best solution.

What you have is what is known as a 'step/direction' controller. This expects to see, two signals. Just a signal that is high for rotation in one direction, and low for rotation in the other, combined with a pulse train,who's frequency you change to specify how fast you want the motor to move.

What voltage are you driving the controller from?. It is rated for up to 40v. The voltage will affect just how fast you can step the motor. The data sheet, does not give a 'pull in' step frequency.

Now the controller you have, has a eight way DIP switch. The top three positions of this, need to be set to '101', to program 2A/phase, which is the current your motor is rated for. Then the bottom three positions need to be set according to how many micro-steps you want to use. As a general comment, unless motors are specifically designed for micro-stepping, the accuracy tends to decline when large numbers of micro-steps are used. Something like 4 to 8 micro-steps is normally reliable with good accuracy. Higher numbers become more 'dubious'....
With your existing PWM setup, the PWM will be generating a pulse train at 2140Hz (20MHz/(4*16*146)). The motor will not start with anything approaching it's maximum torque at this sort of step rate, but this might be quite acceptable, if you were using perhaps 8 micro steps.

Generally, because of the inertia in the system, you would not want to start at 'full speed', and this is why the PWM generator is not the way to go to control this motor. Normally you would start slowly, accelerate to the maximum step rate, and then a little way before you want to stop 'ramp down' to a slow rate to avoid overshoot.
One way to do this, would be to have an interrupt at perhaps 5* the maximum rate that you want to step the motor. In this interrupt, decrement a counter, and if it is zero, trigger a pulse. The pulse need only be 5uSec low, so what you do, is as soon as you 'see' that the counter is 0, pull the pulse signal low, then carry out the operations to re-load the counter, by which time > 5uSec will have passed, and you can raise the signal again. The re-load, involves using a look up table of number of counts wanted between pulses. Have it holding a linear sweep of value, from perhaps 50 to 5. Then when you decide to move a number of steps, you set the table counter to '0', load the first value (which starts the pulse train), and the interrupt automatically counts up the table, with the motor accelerating.
At the re-load, you look to see if:
1) Is the table counter above the top of the table?. If so, you just keep going at this maximum rate.
2) You are 'half way' If so, start counting the table counter _down_, instead of up.
So, something like:

[ntc]

Hi everybody!
Today I buy 2 motor 48BYJ-5V and driver with ULN280c IC, like as a link to make a clock ( 1 motor drive a second, and another drive a minutues with a mechanics structural have before, I need to control 2 motors with gear as:
- 15 rpm with second motor
- 0.25rpm / 0.3rpm with minutes motor
I have designed a new circuit to assembly 2 driver on one board, using ULN2803 IC and tried to write a program to control them.
I have a problems when the max speed of this motor is near with second motor speed, so that I have a delay with it, also the motor is feel hot.
In this project I'm using PIC16F18345 and CCS C ver 5.051.
Thanks for yours supports.





* Motor and driver specs
https://grahamwideman.wikispaces.com/Motors-+28BYJ-48+Stepper+motor+notes

* Schematic design
https://drive.google.com/file/d/0Bz215_lkn4g-ZldzbWU2c3ZoNUk/view?usp=sharing

* Program ( write on PIC18F starter KIT, if this program is OK , Ill port into PIC16F18345 in new design schematic)

[asmboy]

I've used the step/direction type controller and must say that the NCO module in the 16f1509 make it so easy as to be laughable