I am having hard time understanding the Raspberry PI 2 Model B's PINOUT. I have RTC Module I want to use with my PI, but no matter what I do there seems to be NO response at all from RTC. I even scoped the pinout's output. None of their signals change state when I try to write into RTC. Here is the wiring information that I got from a website Hobbytronics

VCC - 3.3V
(DAT) IO  - GPIO#18
(RST) CE  - GPIO#17

For the life of me, I simply can't get anything toggling either. So, could someone please tell me where these PINS are located physically on the Board itself for PI 2 Model B.

  • I have told you where the GPIO are in my answer but like you I find it nonsensical. Perhaps get back to hobbytronics?
    – joan
    Commented Jun 16, 2016 at 19:35
  • That device and software is ancient. Frankly it should no longer be sold. Did you buy it years ago? There are much simpler RTC which use the I2C bus available now.
    – joan
    Commented Jun 16, 2016 at 19:46

4 Answers 4


There are 3 ways to number the GPIO pins. Physical pin numbering, BCM pin numbering and Wiring Pi numbering. The website you refer to is using BCM numbering. The following link list all 3 types plus some other useful info: http://pinout.xyz/pinout/pin28_gpio1

  • You are correct. Hobbytronic confirmed that they are using BCM. Thanks.
    – ThN
    Commented Jun 17, 2016 at 15:22
  • And for those who are using wiringPI to read and write to ds1302 chip like me, then simply in your terminal run gpio readall It will give you all the pins' numbering system including for wiringPI.
    – ThN
    Commented Jun 20, 2016 at 16:21

See http://abyz.me.uk/rpi/pigpio/index.html#Type_3

Top end is closest to SD card slot.

GPIO       pin  pin    GPIO
3V3         1    2      5V
2 (SDA)     3    4      5V
3 (SCL)     5    6      0V
4           7    8      14 (TXD)
0V          9   10      15 (RXD)
17 (ce1)   11   12      18 (ce0)
27         13   14      0V
22         15   16      23
3V3        17   18      24
10 (MOSI)  19   20      0V
9 (MISO)   21   22      25
11 (SCLK)  23   24      8 (CE0)
0V         25   26      7 (CE1)
0 (ID_SD)  27   28      1 (ID_SC)
5          29   30      0V
6          31   32      12
13         33   34      0V
19 (miso)  35   36      16 (ce2)
26         37   38      20 (mosi)
0V         39   40      21 (sclk)
  • Thanks. I have the pinout info for the PI, but what I want to know is where do these GPIO pins located or where can I connect them to on the PI. For instance, where do you connect SCLK on the PI - PIN #40 or PIN #21?
    – ThN
    Commented Jun 16, 2016 at 19:29
  • @ThN You need to get hobbytronics to clarify. The pinout makes no sense.
    – joan
    Commented Jun 16, 2016 at 19:36

I think you are asking the pin numering and naming. Check this link


This is for raspberry pi version 2 model B. And pin number 1 is nearer to the small LED lights of your pi.

  • Yes exactly. That's what I am confused about. For instance, where do you connect SCLK on the PI - PIN #40 or PIN #21?
    – ThN
    Commented Jun 16, 2016 at 19:30

There are many listings of the pins, including some colourful diagrams.

Probably the easiest is on the Pi itself; just run gpio readall which will show the current GPIO state and the designation in all 3 common conventions.

When the B+ first came out with the 40 pin header these were not available so I made my own. I still keep a printed copy next to my Pi. See http://binnie.id.au/Downloads/pins.pdf

I agree with joan. There are better RTC, with inbuilt software support on the Pi. I recommend any module using DS3231.

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