Hardware Description

 

 

 

Table 3-4 Reset signal descriptions (continued)

 

 

Name

Function

 

 

nPBRESET

Push-button reset signal to the FPGA. The signal is generated by pressing the reset

 

button.

 

 

nPBSDCRECONFIG

This signal is generated from the DEV CHIP CONFIG pushbutton and causes a

 

reconfiguration of the ARM926EJ-S PXP Development Chip.

 

 

nPLLRESET

Reset for ARM926EJ-S PXP Development Chip PLL clock circuit.

 

 

nPORESET

Power-on reset to development chip, configuration flash, and expansion memory. The

 

CPU core, all system peripherals, and all system controller registers are reset. For

 

details on system registers reset at different reset levels, see Table 4-4 on page 4-18.

 

 

nPOWERFAIL

This signal shuts down the onboard regulators. It is triggered by the supply voltage

 

falling to less than 9V. (The signal is only valid if the DC IN supply is used.)

 

 

Note

 

 

 

 

 

 

There is a nPWRFAIL signal to the interrupt controller, but this signal is not affected

 

by the power supply voltage. nPWRFAIL can, however, be used to test automatic

 

shutdown code (see Miscellaneous System Control Register, SYS_MISC on

 

page 4-36).

 

 

 

 

 

P_nRST

System reset from PCI backplane.

 

 

P_nTRST

JTAG TRST signal from PCI backplane.

 

 

Note

 

 

 

 

 

 

There is a separate JTAG connector and an independent scan chain on the PCI

 

backplane. The JTAG chain on the PB926EJ-S does not normally extend to the PCI

 

expansion backplane. There is a separate JTAG connector on the PCI backplane for

 

configuring devices on the backplane and on installed PCI cards. There are also links

 

that can be fitted to the PB926EJ-S that connects the two JTAG chains together, but

 

these links are normally only fitted for manufacturing tests.

 

 

 

 

 

nPWRFAIL

This signal is provided by the FPGA to the interrupt controller. User software can test

 

this signal and shut down before a power loss causes a loss of data.

 

 

Note

 

 

 

 

 

 

This signal is not driven by any power-detection logic. It is provided so that custom

 

implementations of the FPGA image have a signal that could be manipulated by a

 

register. Creating such an FPGA image would enable testing of user software that

 

implements a shutdown routine.

 

 

 

 

 

 

 

 

 

 

3-30

Copyright © 2003-2010 ARM Limited. All rights reserved.

ARM DUI 0224I

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ARM ARM DUI 0224I manual Npbreset, Npbsdcreconfig, Npllreset, Nporeset, Npowerfail, PnRST, PnTRST, Npwrfail