AM1705 Datasheet, PDF (29/155 Pages) Texas Instruments – AM1705 ARM Microprocessor

AM1705
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4 Device Configuration
SPRS657 – FEBRUARY 2010
4.1 Boot Modes
This device supports a variety of boot modes through an internal ROM bootloader. This device does not
support dedicated hardware boot modes; therefore, all boot modes utilize the internal ROM. The input
states of the BOOT pins are sampled and latched into the BOOTCFG register, which is part of the system
configuration (SYSCFG) module, when device reset is deasserted. Boot mode selection is determined by
the values of the BOOT pins
The following boot modes are supported:
• NAND Flash boot
– 8-bit NAND
• NOR Flash boot
– NOR Direct boot (8-bit or 16-bit)
– NOR Legacy boot (8-bit or 16-bit)
– NOR AIS boot (8-bit or 16-bit)
• I2C0 / I2C1 Boot
– EEPROM (Master Mode)
– External Host (Slave Mode)
• SPI0 / SPI1 Boot
– Serial Flash (Master Mode)
– SERIAL EEPROM (Master Mode)
– External Host (Slave Mode)
• UART0 / UART1 / UART2 Boot
– External Host
4.2 SYSCFG Module
The following system level features of the chip are controlled by the SYSCFG peripheral:
• Readable Device, Die, and Chip Revision ID
• Control of Pin Multiplexing
• Priority of bus accesses different bus masters in the system
• Capture at power on reset the chip BOOT[15:0] pin values and make them available to software
• Special case settings for peripherals:
– Locking of PLL controller settings
– Default burst sizes for EDMA3 TC0 and TC1
– Selection of the source for the eCAP module input capture (including on chip sources)
– McASP AMUTEIN selection and clearing of AMUTE status for the three McASP peripherals
– Control of the reference clock source and other side-band signals for both of the integrated USB
PHYs
– Clock source selection for EMIFA and EMIFB
• Selects the source of emulation suspend signal of peripherals supporting this function.
Since the SYSCFG peripheral controls global operation of the device, its registers are protected against
erroneous accesses by several mechanisms:
• A special key sequence must be written to KICK0, KICK1 registers before any other registers are
writeable.
• Additionally, many registers are accessible only by a host (ARM) when it is operating in its privileged
mode. (ex. from the kernel, but not from user space code).
Copyright © 2010, Texas Instruments Incorporated
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Device Configuration
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