Reset/Boot Overview; Boot Mode Control And Emifs Multiplexing Control Generation - Texas Instruments OMAP5912 Reference Manual

Reset/Boot Overview

4 Reset/Boot Overview
4.1

Boot Mode Control and EMIFS Multiplexing Control Generation

Table 55. EMIFS Multiplexing Control and MPU_BOOT Mode Signal Generation
for Reset Mode 0
DEVICE_TYPE MPU_BOOT
Production (sampled at
Emulation reset)
Production Don't care
Production Don't care
94 Initialization
The memory interfaces and clock sources are controlled and configured
during power-on reset by external pins and on-chip electronic fuses (eFuses).
The device type changes depending on the programming at the probe of the
eFuse bits. The device type can be observed with the CONF_STATUS[5:4]
bits. See Section 5 for more information on the device types.
The EMIFS chip-selects and the flash protocol can be either address/data
non-multiplexed or address/data multiplexed (note that multiplexing
address/data lines on the EMIFS bus should be considered a completely
different topic from
FUNC_MUX_CTRL(3−12) registers).
There are two ways to affect the EMIFS bus protocol for the data and address
lines.
First, the value of GPIO1, sampled at power-on reset, determines whether or
not the address/data lines are multiplexed when RESET_MODE is 0. GPIO1
affects the EMIFS protocol only at boot time, after which it can be changed by
software (e.g. by the boot ROM code). When RESET_MODE is 1, the
address/data lines are multiplexed at boot time (GPIO1 should be 0 when reset
mode is 1, otherwise the results are unpredictable).
Second, the value of the MAD bit in the EMIFS chip select configuration
registers controls the EMIFS bus protocol. This is a software selectable switch
on a per chip-select basis.
Table 55 summarizes EMIFS configuration at and after boot time.
GPIO1 Boot
(sampled
at reset)
0 Internal on
CS0
1 Internal on
CS0
the pin multiplexing
Default EMIFS
Protocol
(at Boot)
Nonaddress/data
multiplexed
Nonaddress/data
multiplexed
controlled by
EMIFS Protocol
(after boot)
Nonaddress/data
multiplexed
Set by boot code software
(CONF_STATUS[3] = 0)
Address/data multiplexed
Set by boot code software
(CONF_STATUS[3] = 1)
SPRU752B
the