Texas Instruments SM320C6455-EP manual 108

SM320C6455-EP

FIXED-POINT DIGITAL SIGNAL PROCESSOR

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SPRS462B – SEPTEMBER 2007 – REVISED JANUARY 2008

Peripherals used for booting, like I2C and HPI, are automatically enabled after device reset. It is not possible to disable these peripherals after the boot process is complete.

The C64x+ Megamodule also allows for software-driven power-down management for all of the C64x+ megamodule components through its Power-Down Controller (PDC). The CPU can power-down part or the entire C64x+ megamodule through the power-down controller based on its own execution thread or in response to an external stimulus from a host or global controller. More information on the power-down features of the C64x+ Megamodule can be found in the TMS320C64x+ Megamodule Reference Guide (literature number SPRU871).

7.3.4Preserving Boundary-Scan Functionality on RGMII and DDR2 Memory Pins

When the RGMII mode of the EMAC is not used, the DVDD15, DVDD15MON, VREFHSTL, RSV13, and RSV14 pins can be connected directly to ground (VSS) to save power. However, this will prevent boundary-scan

from functioning on the RGMII pins of the EMAC. To preserve boundary-scan functionality on the RGMII pins, DVDD15, VREFHSTL, RSV14, and RSV13 should be connected as follows:

∙DVDD15 and DVDD15MON - connect these pins to the 1.8-V I/O supply (DVDD18).

∙VREFHSTL - connect to a voltage of DVDD18/2. The DVDD18/2 voltage can be generated directly from the DVDD18 supply using two 1-kΩresistors to form a resistor divider circuit.

∙RSV13 - connect this pin to ground (VSS) via a 200-Ωresistor.

∙RSV14 - connect this pin to the 1.8-V I/O supply (DVDD18) via a 200-Ωresistor.

Similarly, when the DDR2 Memory Controller is not used, the VREFSSTL, RSV11, and RSV12 pins can be connected directly to ground (VSS) to save power. However, this will prevent boundary-scan from

functioning on the DDR2 Memory Controller pins. To preserve boundary-scan functionality on the DDR2 Memory Controller pins, VREFSSTL, RSV11, and RSV12 should be connected as follows:

∙VREFSSTL - connect to a voltage of DVDD18/2. The DVDD18/2 voltage can be generated directly from the DVDD18 supply using two 1-kΩresistors to form a resistor divider circuit.

∙RSV11 - connect this pin to ground (VSS) via a 200-Ωresistor.

∙RSV12 - connect this pin to the 1.8-V I/O supply (DVDD18) via a 200-Ωresistor.

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