Hi - I have a SIM900 shield sitting here (the one with the yellow and red pin headers) and I was reading that I could turn on the shield via software by connecting Pin 9 from the shield to pin D9 on the Arduino and doing 1s High, 5s low.
Is it absolutely necessary for me to use Pin D9 on the Arduino? I have a Mega with a TFT shield taking that one up, so I have some Analogs and digital pins from 22 up - no 9.
What's special about D9?
As long as you update your code accordingly, you can use any free pin. If the pin number is hardcoded into a library, that is a little more tricky than just editing your sketch, but it's not too difficult.
pert:
As long as you update your code accordingly, you can use any free pin. If the pin number is hardcoded into a library, that is a little more tricky than just editing your sketch, but it's not too difficult.
OK great - I'll give it a try then! Thanks