Posts: 1
Joined: Fri Jun 03, 2016 10:52 pm

LCD Display + Pushbuttons = GPIO conficts?

Fri Jun 03, 2016 11:16 pm

I'm new to RPi projects. I'm wanting to make a small arcade cabinet using an small LCD display as well as hooking up pushbutton microswitches and a joystick to the GPIO pins. I am using a RPi 2 Model B V1.1.

Both of these things are independantly possible. But it seems like if I try to do both at the same time, there aren't enough GPIO pins to accomplish both.

So this is what i'm looking at:

Waveshare 4inch LCD: http://www.waveshare.com/4inch-rpi-lcd-a.htm

Here is the board for it: Image
http://www.waveshare.com/media/catalog/ ... -a-2_1.jpg

http://www.waveshare.com/img/devkit/LCD ... CD-A-4.jpg

Looking at the connector, it takes up a LOT of the GPIO pins. It appears to use pins 1-26

Now regarding pushbuttons and joysticks, I haven't yet looked in detail as to which GPIO pins they would connect to. It looks like, the available pins left over would be 27-40, which leaves I think 9 GPIO pins and the rest are GND? So does that mean I can use a maximum of 9 pushbuttons when I'm using the LCD?

Are there any alternatives to hooking up or using this LCD screen that would open up some more GPIO pins for me to use? Or is the LCD using actually ALL of the pins with that connector? I can't really tell.

Sorry if these are total noob questions. I'm just trying to figure out my options before diving into this.

Posts: 10419
Joined: Tue Jun 19, 2012 9:46 pm
Location: Essex, UK

Re: LCD Display + Pushbuttons = GPIO conficts?

Sat Jun 04, 2016 12:27 am

The waveshare page you link to shows which (physical) pins are used / free (NC is not connected).

Code: Select all

3, 5, 7, 8, 10, 12, 13, 15, 16	NC	
Looking at http://pinout.xyz/ and leaving out the I2X and UART pins there are 5 general purpose pins available
Then there are another 9 at the 'high' pins.

Posts: 206
Joined: Sat Oct 26, 2013 4:07 am

Re: LCD Display + Pushbuttons = GPIO conficts?

Sat Jun 04, 2016 5:20 am


below is a one more display option which has a 40 pin header instead of 26 pin header so more gpio are easily accessible

http://www.neosecsolutions.com//product ... 7&cPath=20


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