This is a simple question as I am just beginning to get into the world of Arduino. I have MEGA 2560 and a LCD Touch from Sainsmart. I want to be able to hook up the LCD shield and still have access to the 5v line on the Arduino to power a relay module. How can I do this? The LCD shield takes up the 5v...will it even have enough power for both?
I guess more simply put....the LCD shield uses the 5v line and does not stem off of it. What do you guys typically do to tap off of the 5v at this point?
It's a problem, isn't it - I've the ElecFreaks adapter which offers the same problem. Personally I'm thinking of solder-tacking a bit of wirewrap wire onto the power pin on the adapter, and - possibly (undecided yet) soldering a header onto the unused pin holes on the adapter that mimic the 2560 IO ports, and use that as a power feed.
However, the way I'm more likely to go at the moment is to split the incoming power prior to the regulator on the 2560, and feed a separate regulator for all accessories/sensors (one reason, I've a 8-channel relay board and I'd be unhappy sinking this from the microcontroller supply). Separate regulators only cost a couple of quid, although they make testing from a USB connected mega less convenient (but, I'd feel even more compelled to decouple the relay supply from a USB supply).
One other option - check the supply current requirement for the relay - it might be possible to use an otherwise unused discrete output (40mA supply capability) to provide the supply for the relay.
Being that you have a Mega, there are both 5V and GND, 2 pin rails for you to use. You know that big connector that has pins 22 - 54, well the ends are 5V and GND. Do a search for Arduino Mega Pin out diagram, and you will see your options.
HazardsMind: Being that you have a Mega, there are both 5V and GND, 2 pin rails for you to use. You know that big connector that has pins 22 - 54, well the ends are 5V and GND. Do a search for Arduino Mega Pin out diagram, and you will see your options.
...which are fully utilised by the display adapter card.
Do a search for Arduino Mega Pin out diagram, and you will see your options.
There are other pins that supply 5V, not just those two. There should be 4 or 5 pins (depending on rev) that supply 5V. One/two of them are a male pin, the others are female pins.