I have a project that has 2 relay modules. The relay modules are 12V. There is a 12V source that powers both relay modules and the Arduino. To trigger the modules, they have a signal pin, and they get triggered when that signal is low or high.
In this project, both relays turn on or off at the same time. So they are either both OFF or both on. My question is, in order to save pins and wiring, can I connect the signal pins from both relays to the same Arduino Analog or digital pin so when that pin goes high or low all the relays turn ON or OFF?
If yes, is there any limit in how many modules I can connect?
I found that the trigger current is 2-4 mA so as far as I only do 2 relays together I I would be below the 10mA in the worst case, I could do 4 relays if the arduino gives 20 mA per pin.
As long as You keep it a secret which Arduino You use nobody can tell. There are some 20 different Arduinos....
Tha datasheet of "Your Arduino" will tell.