Effect: This setting determines whether the X2 is running in independent motor mode (i.e. controlling two PWM-driven motors independently) or in joint motor mode (wired to control only one motor using both drivers operating in unison). Independent-motor commands are not accepted when running in joint motor mode and joint-motor commands are not accepted when running in independent motor mode. Setting the mode to joint operation will synchronize the timers for the two PWMs and set them both based on the settings for motor 1. In general, joint-motor mode uses motor 1 settings only. The X2 defaults to independent motor mode (motor mode bit = 0) after each hardware reset, so this command really only needs to be sent at the beginning of your program if you wish to run in joint motor mode (motor mode bit = 1). This setting cannot be stored in EEPROM and hence to operate in joint mode the mega644 must always send this command after a hardware reset.
If you want to run your X2 in joint motor mode, you should connect one terminal of your motor to the two M1 outputs and the other terminal of your motor to the two M2 outputs.
It is important to note that current sensing is not possible in joint motor mode. The Set Current Limits command (192—Section 3.a.10) will have no effect in joint motor mode and the Get Average Motor Current command (216—Section 3.a.12) will not return anything meaningful.
Values sent: motor mode (1 bit)
command byte = 214 | motor mode bit