Hardware Reference
In-Depth Information
A couple of GPIO pins have pull-up resistors. Figure
10-1
shows that GPIO pins 2
(SDA1) on P1-03, and GPIO 3 (SCL1) on P1-05, have an 1
.
8
k
Ω pull-up resistor. This
should be taken into account if you use these for something other than I2C.
Figure 10-1.
GPIO P1 header
The layouts of headers P1 and P5, where the GPIO pins are made accessible, are
documented in Chapter 3.
■
p5 was not present prior to version 2, but both Models a and B now include it
(without header pins).
Note
Configuration After Reset
Upon reset, most GPIO pins are configured as general-purpose inputs with the exceptions
noted in Table
10-2
. (Figure
10-2
applies to version 2, Models A and B.) The Pull-up
column indicates how the internal pull-up resistor is initially configured. The pull-up
resistors apply when the GPIO is configured as an input pin.