Need help connecting arduino uno -> 2x shift registers -> 2x 8 relay module

Projects General Guidance
1

Hey there,

I´m planning a new project where I need to control 16 I/O buttons.

So I decided to use 2 shift registers 74HC595 (breakouts) + 2x 8 relay modules.
Because I´m pretty new to this electronic world I went through different tutorials. But I´m still confused how to connect all together.

Connecting Arduino to first shift register:
http://bildr.org/blog/wp-content/uploads/2011/08/shift-Register-breakout-hookup1.png
The second shift register is no problem too. I set it parallel to the first one and connect it.

I bought 2 of the following 8 relay module:

Each shift register has 8 outputs so each shift register will be connected to one relay module.
But what ground and VCC?
I will run the 8 relay module with seperated power supply so the arduino doesn´t need to power supply the relays.

I hope someone can help me with this "simple" problem.

Thanks in advance.

Mare00

2

How are you reading the buttons? The '595 shift registers do not come into play there, do they?

Connect the control side ground of the relay card to the Arduino & '595 GNDs. They all need a common reference point.

3

CrossRoads:
How are you reading the buttons? The '595 shift registers do not come into play there, do they?

Connect the control side ground of the relay card to the Arduino & '595 GNDs. They all need a common reference point.

I´m not sure what u mean. "Reading buttons"?

Here is a better picture how it should be connected.

But I don´t know where to connect the read marked pins.

4

I think I´m only missing the how to connect the GND from relay module and where to connect the power supply for the relay module

5

Do NOT connect relay ground to Arduino ground.
If you do, you don't have opto isolation.

Remove the JD-VCC jumper
Connect relay VCC (next to input 8 ) to Arduino 5volt.
Now you should be able to activate the relay indicator LEDs by writing LOWs to the pins.

Connect a separate 5volt supply to JD-VCC and relay ground.
The same relay supply can be connected to the second relay board's JD-VCC and ground.

Those relays use 75-80mA each when active, so use a 5volt/1.5Amp (minimum) regulated supply.
A 5volt tablet charger might do.
Leo..

6

Wawa:
Do NOT connect relay ground to Arduino ground.
If you do, you don't have opto isolation.

Remove the JD-VCC jumper
Connect relay VCC (next to input 8 ) to Arduino 5volt.
Now you should be able to activate the relay indicator LEDs by writing LOWs to the pins.

Connect a separate 5volt supply to JD-VCC and relay ground.
The same relay supply can be connected to the second relay board's JD-VCC and ground.

Those relays use 75-80mA each when active, so use a 5volt/1.5Amp (minimum) regulated supply.
A 5volt tablet charger might do.
Leo..

Thanks for your fast reply.
I adjusted my painting.

I hope everything is ok now.

1182×776 56.7 KB

7

Diagram seems ok.
Leo..