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Topic: TFTLCD shield takes up too many pins on arduino Uno R3 (Read 911 times) previous topic - next topic

ddang

http://arduino.cc/en/uploads/Main/ArduinoUno_R3_Front.jpg
The above is a link to the pins for the R3 for convenience. I bought a TFTLCD Touchscreen shield from Adafruit. The problem is it takes up all the pins except the two on the top and bottom on the left side as shown in the link above.

My plan is to have the arduino send a High/Low signal to another microcontroller (A Pic microcontroller) and I need to power the arduino using something like a 9V battery. The problem is these pins are already taken by the touchscreen shield.

What do you guys recommend? I want to try avoid buying anything extra for this purpose as that would take time to ship.

HazardsMind

Check your data sheet, you may have at least 2 pin available. If so, you can use soft serial.
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https://github.com/AndrewMascolo?tab=repositories

JoeN

Adafruit says that it uses 12 lines.  You can see them marked in the image:

http://www.adafruit.com/index.php?main_page=popup_image_additional&pID=376&pic=0&products_image_large_additional=images/large/tftshieldback_LRG.jpg

Unused pins are accessed through the headers for convenience.  Just because there is a header pin doesn't mean that it is used.  Doesn't that leave you enough?  Pick from the others.
I have only come here seeking knowledge. Things they would not teach me of in college.

ddang


Adafruit says that it uses 12 lines.  You can see them marked in the image:

http://www.adafruit.com/index.php?main_page=popup_image_additional&pID=376&pic=0&products_image_large_additional=images/large/tftshieldback_LRG.jpg

Unused pins are accessed through the headers for convenience.  Just because there is a header pin doesn't mean that it is used.  Doesn't that leave you enough?  Pick from the others.

Oh I see. Are you suggesting that I jump some wires to the pins that may have been taken, but not used?

JoeN



Adafruit says that it uses 12 lines.  You can see them marked in the image:

http://www.adafruit.com/index.php?main_page=popup_image_additional&pID=376&pic=0&products_image_large_additional=images/large/tftshieldback_LRG.jpg

Unused pins are accessed through the headers for convenience.  Just because there is a header pin doesn't mean that it is used.  Doesn't that leave you enough?  Pick from the others.

Oh I see. Are you suggesting that I jump some wires to the pins that may have been taken, but not used?


Yes, you should be able to use any of the pins that shield does not use.  I would just double check the datasheet or whatever documentation Adafruit provided.  I suspect they are the ones that are not marked on the shield and left blank.  If there are no obvious traces going to those pins they are probably not touched by the shield.
I have only come here seeking knowledge. Things they would not teach me of in college.

ddang




Adafruit says that it uses 12 lines.  You can see them marked in the image:

http://www.adafruit.com/index.php?main_page=popup_image_additional&pID=376&pic=0&products_image_large_additional=images/large/tftshieldback_LRG.jpg

Unused pins are accessed through the headers for convenience.  Just because there is a header pin doesn't mean that it is used.  Doesn't that leave you enough?  Pick from the others.

Oh I see. Are you suggesting that I jump some wires to the pins that may have been taken, but not used?


Yes, you should be able to use any of the pins that shield does not use.  I would just double check the datasheet or whatever documentation Adafruit provided.  I suspect they are the ones that are not marked on the shield and left blank.  If there are no obvious traces going to those pins they are probably not touched by the shield.

Thanks for the replies.
Even if a pin is taken by the shield from Adafruit's touchscreen, couldn't I still jump that pin by connecting a wire to it? Or can you not make 2 connections to the same pin?
The reason for this is the touchscreen uses the V_in pin. If I want to apply an external voltage source, I would need to use that pin for the voltage source and for one of the touchscreen's respective pin. So basically, I need to make 2 connections (one from the touch screen and one from an external V source) to the same arduino V_in pin.

JoeN

Voltage and ground pins can certainly be shared, subject to current limits.  Under certain circumstances logic pins can even be shared, but it takes device cooperation, and it's best to assume they won't cooperate unless the specs say they can (i.e. you can set one device's pins high-z while you use the other device, etc.)
I have only come here seeking knowledge. Things they would not teach me of in college.

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