Elec Freaks 2.4" Colour TFT touch screen panel (HCARDU0083)

LCD, TFT, OLED, LED modules
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Re: Elec Freaks 2.4" Colour TFT touch screen panel (HCARDU00

Post by DIY_Monster » Mon Aug 08, 2016 9:49 pm

I have had the HCARDU0083 for some time now as well as the adapter shield and, yes while it's great, i have been struggling to identify any unused pins. For example, although I have not tried, I assume that if I did not want the touch feature I could re-deploy those pins which are explicit. But what pins (if any) are free if I want full functionality?
Many thanks.

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Re: Elec Freaks 2.4" Colour TFT touch screen panel (HCARDU00

Post by andrew » Tue Aug 09, 2016 9:24 am

I've added an answer to the first post of the adapter shield thread as the question is more relevant there...

http://forum.hobbycomponents.com/viewto ... 633&p=3728

.... but for convenience here is a copy:
What pins (if any) are free if I want full functionality?

If you need to use all the features of the screen, i.e. display, restive touch sensor, and SD card interface then unfortunately due to the limited number of I/O pins available on an Arduino Uno there are no spare pins available. If you don't need the SD card or touch screen features then it is possible to free up some pins. although you will need to reference the adapter shield schematic as for some pins there may still be hardware attached. Additionally, as the screen, SD, and resistive touch all use chip select (CS) lines, it is possible (again with consideration to the schematic) to multiplex some of these pins. For instance if you wanted at attach some push buttons you could connect them to Arduino's digital pins used for the screens data pins. You could then briefly configure the pin(s) as an input with pullup whilst reading the state of the button(s). However in this example as there would be no way to guarantee that a button wouldn't be pressed at the same time data is being written to the screen. You would therefore need to consider applying some sort of buffering such as putting a resistor in series with the button which is low enough in value to pull the pin low but not too low that it would overload the maximum output current capabilities of the Arduino's digital pin/ screen should bus contention occur.
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