Compatibility between shields Despite that I am new to Arduino, I am tasked to invent a serious alarm system and I chose Arduino.
I study electronics, but virtually I am a software programmer and C is my area of expertise.

I ordered the parts I think I will need and the time is immensely pushing me.
The delivery goes slow and it needs to happen before our planned vacation, because
we've been robbed several times so far.
I need to know if I will need another gadgets to deal with a problem I've discovered suddenly.


  >


I plan to stack up these 3 shields


Arducam-F Shield V2 Camera module shield /w OV2640
3.5" TFT LCD Display Touch Screen Module
SIM900 Quad-band GSM/GPRS Shield


From what I've learned the shields 1 and 3 are compatible, as the arducam uses
CS/SD, ICSP, VCC, GND, SDA and SCL
or according to standard pin out table:
I2C_SCL, I2C_SDA, SPI_SCLK, SPI_MISO,
SPI_MOSI, 9, 10, Reset, 5V, GND
and the GPRS shield uses D7 and D0/D1(or D2/D3), 3 I/O ports. For D7.

The arducam however seems to be not stackable and as far as I can not see it is impossible
to make it stackable (Maybe even if I drill holes and solder stackable shield headers)
So it must be the topmost shield.

What about the LCD shield? I also learned that such shields use a lot of pins, so it is possible that there will be no free pins. I also ordered lots of jumper wires of any kind, if that can help.
Maybe I don't need to wire each of the pins in order to make it work or do some extra coding to get it work? I also don't necessarily need the other shields to work while I operate with the screen, so maybe there is a way I can connect/disconnect shields separately with a program or something else I can buy. I have a feeling that this LCD shield will leave no pins for the other shields and I should connect the arducam on another way since it is not stackable.
Its not just a question of the stackability of the shields and the clash of pins you also need to consider what the shields do.

Stacking the GSM shield under the LCD is going to restrict is tx/rx power unless you have an external aerial.

The LCD will require a large amount of memory and processing power, a 3.5" inch display is really going to push an Uno to the edge, you aren't going to get much time for servicing the GSM and camera.

The camera is also going to require a large amount of RAM and processing time to handle still images.  If you are processing video then I really doubt you will be able use the other shields.

You don't say if you are experienced in Embedded development.  Its different to Linux or Windows dev where resources are almost limitless.  If you don't have experience then you might find the transition quite hard.

Your question was are they compatible, I don't have the evidence but I would say no because of the resources they consume.  Sorry I can't see this project going anywhere fast. :(