Yes, it certainly IS possible to use TWO BT7690 half bridges to drive a Bipolar Stepper Motor. (This is the kind of stepper motor with 4 wires and two separate coils)
You can use EXISTING Arduino code to do this, without ANY editting of the sketches (see URL below). You simply need to use the same 4 Arduino DIGITAL pins as inputs to the TWO half bridges, and drive the pins labelled (misleadingly) as LPWM and RPWM as digital output pins (i.e., with either logic HIGH or logic LOW values and digitialWrite(), and NOT with PWM signals and analogWrite().
For clear explanations and already written Arduino UNO code, see the excellent tutorial and directly applicable sketches provided here:
Wiring from an Arduino UNO to the TWO half bridge boards is accomplished as follows
NOTE: this wiring is to connect an Arduino UNO to a single BIPOLAR STEPPER MOTOR Bipolar (4 wire, 2 coils).
Polarity of connection the coils doesn’t matter, so long as ONE coil is connected to M- and M+ on ONE half bridge output terminal, and the OTHER coil is connected M- and M+ on the OTHER half bridge output terminal.
Inverting the polarity on either coil simply changes the motor rotation direction for a given stepper pulse. (and the stepper motor can be stepped in EITHER direction by changing the sign of the number of steps in the Arduino sketch.)
the suffixes _1, _2 below indicate which of TWO BT7690 half bridge boards (and which of the two stepper coils) is involved in the connections.
CONNECTIONS to FIRST BT7690 H-bridge module half bridge:
VCC_1 to arduino +5V power (from Arduino UNO or similar)
GND_1 to arduino ground
L_EN_1 to arduino +5V power (ENABLE= TRUE)
R_EN_1 to arduino +5V power (ENABLE= TRUE)
L_PWM_1 = arduino digital pin 8
R_PWM_1 = arduino digital pin 9
STEPPER MOTOR CONNECTION (COIL_1)
B-_1 = GND of STEPPER MOTOR SUPPLY
B+_1 = Vm of STEPPER MOTOR SUPPLY (note Vm can be DIFFERENT from Arduino Vcc
and supply needs enough current for motor (1A or more))
M-_1 = one end of STEPPER MOTOR COIL_1
M+_1 = other end of STEPPER MOTOR COIL_1 (invert M- & M+ still works but direction reverses)
CONNECTIONS to SECOND BT7690 H-bridge module half bridge:
VCC_2 to arduino +5V power (from Arduino UNO or similar)
GND_2 to arduino ground
L_EN_2 to arduino +5V power (ENABLE= TRUE)
R_EN_2 to arduino +5V power (ENABLE= TRUE)
L_PWM_2 = arduino digital pin 10
R_PWM_2 = arduino digital pin 11
STEPPER MOTOR CONNECTIONS
B-_2 = GND of STEPPER MOTOR SUPPLY
B+_2 = Vm of STEPPER MOTOR SUPPLY (note Vm can be DIFFERENT from Arduino Vcc
and supply needs enough current for motor (1A or more))
M-_2 = one end of STEPPER MOTOR COIL_2
M+_2 = other end of STEPPER MOTOR COIL_2 (invert M- & M+ still works but direction reverses)
NOTE: you should provide a suitabl HIGH current and probably LOW voltage power supply to run the stepper motor coils (This supply has its GND connected to B- and is +V terminal connected to B+ on each half bridge output terminal).
This motor supply is separate from the small +5V supply coming from the Arduino into each Vcc pin on each half bridge. The Arduino +5V supply is NOT adequate to power a typical stepper motor, so do NOT connect +5V from the Arduino to the B+ of the H-bridge: you may fry your Arduino if you do.
You may need to insert a suitable high Power low Ohm value currently limiting resistor Rs (e.g., say a 1 Ohm 5 Watt resistor), in series between the Vm supply and B+ terminals leading to the stepper motor coils. The resistance is chosen to set the motor current to have adequate torque, but to not exceed the motor current rating. The Rs value will depend on the stepper motor coil resistance (and inductance, if you are running the motor fast).
In my case, I was able to omit the Rs current limit altogether and achieve an acceptable current. I made a direct connection of my particular motor to my separate high current Vm supply. Coincidentally, my Vm supply was also +5V (same as the Arduino supply Vcc). However, I could have chosen Vm to be larger or smaller, depending on my stepper motor specs and torque requirements.)
