CODEWITHSUNDEEP
raspberry-pi
brunshte
brunshte

Reputation: 321

How many GPIOs does Raspberry Pi A+ really have?

Could someone clarify for me why official documentation of RPI A+ says that it has 40 GPIOs while other sources, such as forums, online courses, and others say that it has 54 GPIOs? What is each one talking about? Is there a difference in types of GPIOs that each source is referring to?

RPI Tutorial by University of Cambridge https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/ok01.html : "There are 54 GPIO pins, so we need 6 sets of 4 bytes, which is 24 bytes in total."

Adafruit Website RPI specs https://www.adafruit.com/product/2266 : "It's still compatible with all Pi operating systems and software, and has the exact same 40 pin GPIO connector and camera/display sockets"

Upvotes: 0

Views: 59

Answers (1)

Dark Sorrow
Dark Sorrow

Reputation: 1897

BCM2835/BCM2835 micro-processor have 54 general-purpose I/O (GPIO) lines in total. This what RPI Tutorial by University of Cambridge is claiming but out of these 54 GPIO lines only 28 general-purpose I/O (GPIO) come on the external J8 header which can easily be interfaced with outside world. 12 pin are used as power pins +3.3V (2), +5V (2) and GND (8).

Upvotes: 1

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