sorry for newbie question, but I'm quite new to Arduino and I'd like to know bit more before I order parts.
Basically I need 16 relays controlled via I2C.
I've read a bit over the internet and found ready product (https://shop.controleverything.com/products/16-channel-relay-controller-i2c) but it costs 144$ :o
Because I need this for hobby project I want to make something bit cheaper.
I found two 8 Channel Relay boards
They work on 5V so they are perfect for my usage.
The hard part for me is choosing I2C Expander.
I found couple of options: -SX1509 16 channels
-PCF8574 8 channels
-MCP23017 16 channels
I'm thinking about SX1509 or MCP23017. Both work on 5V.
I have some questions about wiring before I decide and order items:
Which one I should choose. As I said I'm new to this, but I want to try building it.
Can I connect directly I2C from Arduino to SX1509 or MCP23017 and then to those two relays? I've connected single relay boards before but never 16 of them. 16 Channel Relay Board has external power supply, should I connect external power supply for those relays? How should I calculate current? Can I count 100mA for single relay? So for 16 relays I'll need 1.6A 5V?
SX1509 works on 5V, but do I need extra connectors for it?
I'll be grateful for generale hints on this. I'm planning to use this with MQTT server. I'm C# developer, but I thing I can handle programming, but I need guidance on wiring.
Sorry for asking so much questions, but I think it's better to ask twice that to burn even single device.