Motor driver based on btn7971

Motor driver based on btn7971.
1. How to achieve signal isolation?
Before explaining how to achieve isolation, let's talk about why it is necessary to isolate the driver chip and the microcontroller.
As mentioned before, the amount of current that the IO port of a single-chip microcomputer can endure is very small, but the motor drive it controls is a power part that often measures tens of amps. Therefore, in order to protect the single-chip microcomputer from being damaged by the power part, If damaged by large currents, certain forms of protective isolation measures are necessary. In addition, the use of isolation devices also has the effect of changing the drive level.
(In fact, the necessity of protection should depend on the specific situation. It is not accurate to talk about it in general terms. An article will be published later that specifically discusses driver protection.)
There are actually two major categories of isolation that can be thought of: Optocoupler isolation and logic isolation; Optocoupler isolation mainly refers to the use of specialized optocoupler isolation chips to achieve circuit topological isolation through its internal electrical->optical->electrical conversion, that is, between the input signal and the output signal. It is inherited through light rather than electricity, so the isolation effect is also achieved.
Logic isolation is a name I made up myself~~~~ but it is quite vivid. The literal meaning is to achieve isolation through logic devices. Two major types of devices are used here, namely logic gates and operational amplifiers (usually logic Door). The main idea is to isolate the input and output through the high impedance relationship between these gate circuits and the input and output of the operational amplifier.
There are two types of optocouplers, one in the form of an integrated chip, such as the famous TLP250. This type of chip requires a separate power supply, and as a driver itself, it has driving capabilities. It is actually used purely for input and output isolation. Overkill. There is another type of optocoupler, which is a device with four pins that simply implements optocoupler isolation. In our driving scenario, if you choose an optocoupler, the second type is actually enough.
Similarly, logic isolation is generally implemented using integrated logic gate chips. The operational amplifier driving capability is too weak and is generally not used for this purpose. This time we used a three-state logic buffer 74LS541 produced by TI to achieve isolation between input and output.
 
After clarifying the circuit composition, there is no need to cooperate with the external components. The 7960 is directly powered by battery power, and the 541 is powered by an LDO after voltage reduction, and then the output terminal is connected to a quick-plug terminal for convenient connection with the motor.
It's probably like this.
After changing the computer, the schematic diagram can no longer be found qwq. I only give a waveform diagram of the board and the output after welding.
The left is the power board, and the right is the driver board
 
driver output waveform.