The GPIO Pin Layout
The GPIO interface is the series of 26 pins (in two rows of 13 pins each) that stick up at the upper-
left corner of the Raspberry Pi circuit board. They directly interface with specific pins on the
Broadcom integrated circuit chip and are assigned names based on the chip signal. Some pins have
dual functions from the Broadcom chip, depending on how you program the chip. Table 24.1 shows
the signal names and the alternate functions for each of the pins. When you start coding your Python
scripts, you’ll need to know which pin or signal you need to work with.