The thing about modules like that is that they have opto-isolators that will allow you to completely isolate the microprocessor from the relay coils. For convenience, you can defeat that protection to some extent by sharing a power supply.
The thing about modules like that is that they have opto-isolators that will allow you to completely isolate the microprocessor from the relay coils. For convenience, you can defeat that protection to some extent by sharing a power supply.