Building the Board

Like many people, I've benefited greatly over the years from free designs that people have graciously posted on the web. In light of this I am providing enough information for you to build your own stepper driver. This includes:

For information about making boards via toner transfer you can check out Making PCB Boards or search via Google. Since this is a double sided board it's not the easiest to make but I did prepare the prototype this way so it is doable. Also you'll need to manually bridge the vias and there are a few so some patience is required. In small quantities the parts cost about $20-25. Realistically, sending the gerbers to get professional boards is probably the best bet but I leave that to you to decide.

Here is the bill of materials. The

Qty Description Part Number and (Package)
1 dsPIC microcontroller dsPIC33FJ12MC202 (SOIC-28)
1 Dual H-Bridge L298N (multiwatt 15)
2 Quad Op-amp TSV994IDT or MCP6024-E/SL (SOIC-14)
1 470uF 50V (or similar)  
1 Variable voltage regulator LD1117
8 Fast rec. diodes (<50ns) 1A 100V ES1B-TP (DO-214AC)
3 10uF ~10VElectrolytic Caps SMD
2 0.1 sensing resistor 1206 SMD
2 220 ohm resistor (current limiting) 1206 SMD
4 470 ohm resistor 1206 SMD
1 820 ohm resistor 1206 SMD
3 1K ohm resistor 1206 SMD
1 2.7K ohm resistor 1206 SMD
2 4.7K ohm resistor 1206 SMD
5 5.1K ohm resistor 1206 SMD
4 6.8K ohm resistor 1206 SMD
6 10K ohm resistor 1206 SMD
1 22K ohm resistor 1206 SMD
1 27K ohm resistor 1206 SMD
4 100K ohm resistor 1206 SMD
4 22pF ceramic 1206 SMD
2 100pF ceramic 1206 SMD
12 0.1uF ceramic 1206 SMD
1 10uF ceramic 1206 SMD
1 Green LED 1206 SMD
1 Red LED 1206 SMD
1 8Mhz Ceramic Osc.  
1 5K to 10K pot for max. current set almost any small pot can fit with some leg bending.
3 2 position 0.1" header  
1 5 position 0.1" header (opt.)  


When you power up the board it will first flash its LEDs. After about 2 seconds it will measure the applied motor supply voltage. If that supply isn't yet turned on, press the reset button on the driver board to measure again. The variable potentiometer can be used to adjust the maximum current from 0 to 2A. Below a certain value, the stepper motor will begin to hum erratically. Above 1.7A, the RED ove rcurrent LED will come one and the motor will not function correctly.

Well, that's it for now.

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