AM3874 datasheet(144/361 Pages) TI

144 / 361 page

AM3874, AM3871

SPRS695C – SEPTEMBER 2011 – REVISED DECEMBER 2013

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Device Configurations

4.1

Control Module Registers

4.2

Boot Modes

The state of the device after boot is determined by sampling the input states of the BTMODE[15:0] pins

when device reset (POR or RESET) is de-asserted. The sampled values are latched into the

CONTROL_STATUS register, which is part of the Control Module. The BTMODE[15:11] values determine

the following system boot settings:

•

RSTOUT_WD_OUT Control

•

GPMC CS0 Default Data Bus Width, Wait Enable, and Address/Data Multiplexing

For additional details on BTMODE[15:11] pin functions, see Table 3-1, Boot Configuration Terminal

Functions.

The BTMODE[4:0] values determine the boot mode order according to Table 4-1, Boot Mode Order. The

1st boot mode listed for each BTMODE[4:0] configuration is executed as the primary boot mode. If the

primary boot mode fails, the 2nd, 3rd, and 4th boot modes are executed in that order until a successful

boot is completed.

The BTMODE[7:5] pins are RESERVED and should be pulled down as indicated inTable 3-1, Boot

Configuration Terminal Functions.

When the EMAC bootmode is selected (see Table 4-1), the sampled value from BTMODE[9:8] pins are

used to determine the Ethernet PHY Mode selection (see Table 4-7).

When the XIP (MUX0), XIP (MUX1), XIP w/ WAiT (MUX0) or XIP w/ WAiT (MUX1) bootmode is selected

(see Table 4-1), the sampled value from BTMODE[10] pin is used to select between GPMC pin muxing

options shown in Table 4-2, XIP (on GPMC) Boot Options [Muxed or Non-Muxed].

For more detailed information on booting the device, see the ROM Code Memory and Peripheral Booting

chapter of the AM387x Sitara™ ARM Processors Technical Reference Manual (Literature Number:

SPRUGZ7).

144

Device Configurations

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