In the motor category, the system consists of the main control module, the sensor module, the mechanical structure module, the power module and so on. The main application of the hardware motor, sensor, control chip composed of motor drive circuit. The following modules are demonstrated and analyzed. one. L298N integrated chip. L298N is to play the role of amplification current. Microcontroller current is small, can not drive the motor. L298N has four input, four output; there are two enabled side, under normal circumstances, you can directly to the EA, EB two enable high end, directly through the control input (then the microcontroller I / O port, programming Output PWM signal) to control the motor. L298N also in the external access to some small components to prevent the chip burned. In general, the L298N as a current amplifier can be used, as for the motor speed and steering, this only with the control signal PWM, and L298 has nothing to do. two. L297 integrated chip. It is stepper motor front drive circuit, L298N is the drive, L297 is the controller, with L298N need to write their own control pulse timing, and with the L297 together with only a simple input pulse on it. three. UNL2803 or UNL2003. Are used to drive the 5V relay. Are the maximum to withstand the 50V, the maximum current 500MA, but UNL2803 is 8-channel, UNL2003 is 7-channel, UNL2803 UNL2003 more than a channel. four. UC3717AQ integrated chip, which is used to drive two-phase stepper motor dedicated chip It consists of controllable logic input, current sensor, built-in protection diode with monostable output. Two UC3717 and some external components can form a complete two-phase stepper motor drive system.