Sysboot Configuration - pandaboard OMAP 4 Series System Reference Manual

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2.6

The OMAP4430 Processor has eight SYSBOOT inputs. These inputs are sampled after a board reset, and

determine the booting and operating mode of the OMAP4430 Processor. The upper two inputs

(SYSBOOT[7:6]) control the clocking modes of the part (i.e. enabling/disabling the internal oscillator to

allow using a crystal input or oscillator). They are currently set to "11" and should not be changed.

The lower six inputs, SYSBOOT[5:0] determine the type and order of memory or peripheral booting.

SYSBOOT[5] determines whether memory or peripheral booting is preferred. The SYSBOOT

definitions may be found in the OMAP4430 TRM, but are included here for convenience. See Table 2 on

page 22 for the SYSBOOT definitions for peripheral preferred booting, and Table 3 on page 23 for

memory preferred booting SYSBOOT definitions. The shaded row in Table 2 is the default configuration

of the PandaBoard.

If it is desired to change the SYSBOOT configuration, resistors may be added or removed from the

SYSBOOT[5:0] lines. The SYSBOOT[5:0] lines have weak internal pull-down resistors, so removing the

resistor will result in the line being sampled as a '0' at reset, and installing a 3.3K or lower value resistor

will result in the line being sampled as a '1' at reset. See Figure 3 on page 24 for the location of the

resistors on SYSBOOT[5:0]. These resistors are connected to OMAP4430 as follows:

•

R123: SYSBOOT0

•

R136: SYSBOOT1

•

R128: SYSBOOT2

•

R119: SYSBOOT3

•

R135: SYSBOOT4

•

R137: SYSBOOT5

NOTE: Do not use pull-up resistance values higher than 3.3Kohm on the SYSBOOT lines. This would

create a voltage divider with the internal OMAP pulldown, potentially causing an invalid value to be

internally latched for SYSBOOT.

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OMAP

o Earpiece Output

o FM Input

o Aux Output

o Hands-free 8 ohm driver

o Dual Vibrator

Misc Control

o GPO

o I2C (high speed)

o Power on/off

Power

o Internal LDOs

o Internal negative charge pump