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.
 
 
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