A. PREFACE
There are many integrated stepper motor controller chips selling at the market right now. Stepper motor is a kind of small permanent magnet motor for hobbyist uses (like disk stepper motor drive), I prefer to make it from discrete IC, beside the the price can be cut down to about a half or third the price for dedicated controller. Dedicated controller has many option integrated. When we build it from discrete, this option depends on the purpose or the complexity of the circuits. It also take the layout design more complex compare to dedicated version.
B. SCHEMATIC
This circuit schematic I got from the book : "Robot Builder - Bonanza" refer to the reference book below for detail, and it purpose to support my little arm robot driver. The driver plan to use all stepper motor type. There are 6 stepper motors, but this circuit only for 4 drivers stepper motor controller, because 2 stepper motors used its own driver. The drive only can move maximum up to ± 360 ° or below it, so to protect the mechanical drive from worn out or over drive, we put the limit switch delimiter circuits. If one of the limit switch touch, move to this direction not allowed (motor stop), but it can move to another direction. For the output driver, because its only take up to 300 mA, I used an ULN driver, this can sink or source up to 500 mA. Of course you can use any transistor driver, like usual, but the layout will be to complex. But my design not a complete state right now, it may be changed to something else when I found difficulty or obstacles. Here are the schematics for this arm robot :
- Diagram Block for 6 degree of freedom arm robotic
- Stepper schematic circuits for 6 drive controller
Note that you must grounded pin 4, 7, 9 and 12 of IC type CMOS version 4027 (TTL version 74LS76). I used a CMOS version circuit.
One of dedicated stepper motor controller chis is UCN5804B, this chip can drive small stepper motor, like our purpose. First I want to use it, but the price is about 2 to 3 times when I wired it from discrete. But it has many options like selected input half step or full step, direction input, enable input. Still a good one to choose.
C. LAYOUT
I already design the PCB of these circuits. It consists of 3 parts : power supply board, stepper driver board and delimiter control board. But infact I also drawing the circuit using UCN5804B and driver board for stepper motor which has take more than 500mA current. Here are the layouts :
D. STEPPER MOTOR SPECIFICATIONS
Among stepper motors that I could find until now here are the specifications and many important things about it :
All the first 4 stepper motors can be connect bipolar or unipolar 2-phase, the last one only bipolar 2-phase.
E. CONVENSION OF TERMINAL USED
Convension for connectors description :
F. ANOTHER KIND OF STEPPER CONTROLLER
Another kind of stepper controller introduce by elector - elektuur magazine 1996 edition, using a GAL type chip (GAL16V8). This chip can be programmed to be a dedicated stepper controller, same like the dedicated UCN5804B type. But it needs a programmer. Besides that it also cheaper too (about fourth to fifth price from the dedicated controller). I use GalBlast Ver1.4 type programmer, create by Manfred Winterhoff. It is free with software. This is my GAL programmer prototype, with modification from original. I used a voltage doubler to powered programming voltage, so I can use a single 12V-AC supply. Using GAL16V8 type, it takes 6 inputs (clock, direction, half/full step, step enable, reset, and output enable), and 7 outputs (3 to generate the binary sequence, and 4 for the output stepper motor). Here is the package before and after modification. First I tried to program using the jedec file created by him, but the file failed crc check. So I compile it again using PLAN2 program (eqn2jed) from National Semiconductor, and make some changes to the equation logic. I plan to use this controller to drive bipolar or unipolar stepper types for my MRD-04 robot and my another projects 'brute' - cnc pcb milling. Below are my stepper motor data :
Here is the schematic related to the stepper motors above and PCB layout of my GAL stepper controller prototype. Note that +Vcc trace are connect together both for IC/signal and for stepper motor power supply. If stepper motor power used Vcc more than +5V than this trace must be cut out. I used 2 kind of Vcc; ie: +5V and +9V. I can't find the perfect resistance for the coils. For more info about how to determine the resistance, please download the program at http--www.e-zflight.com-files-stepcalc102.zip. The complete GAL 16V8 stepper motor controller package can be obtain here.
G. MODIFIED 5-PHASE STEPPER CONTROLLER
This is one of the alternative to run bipolar or unipolar stepper motor using my 5-phase stepper controller with changed firmware. First of this firmware ask by a reader (an experimenter), Roberto, who build my CNC concept design. But he has difficulty to find the same stepper motor type like mine (Vexta 5-phase stepper motor, this may obsolete, only can be found at second market/junk market). So he change it to the usual bipolar/unipolar type stepper motor, without change the hardware too much. Very little change to the hardware any way, but the PIC microcontroller must be reprogrammed to support the new step sequence. The PIC still use PIC16F84A type. Change to the I/O map are like this :
- I/O port A-0 = LED indicator phase-1 stepper
- I/O port A-1 = LED indicator phase-2 stepper
- I/O port A-2 = LED indicator phase-3 stepper
- I/O port A-3 = LED indicator phase-4 stepper
- I/O port A-4 = Reserved (was changed)
- I/O port B-0 = Coil phase-1 stepper
- I/O port B-1 = Coil phase-2 stepper
- I/O port B-2 = Coil phase-3 stepper
- I/O port B-3 = Coil phase-4 stepper
- I/O port B-4 = Input select half/full step (was changed)
- I/O port B-5 = Input step pulse
- I/O port B-6 = Input direction
- I/O port B-7 = Input enable motor
Note that for I/O port A-4 pin, it will become reserved and I/O port B-4 pin, it will become selected input for half or full step. The others are still the same. Here is the complete firmware for this '2-phase stepper controller' by my concept and design. Enjoy the new era!
Precision motion control stepper motor when needed. Each movement of the motor shaft a precise distance from the step. I found mine at an electronic surplus store.
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