ARM ARM DUI 0224I manual Status and system control registers

Programmer’s Reference

4.3Status and system control registers

The PB926EJ-S status and system control registers enable the processor to determine its environment and to control some on-board operations. The registers, listed in Table 4-4 on page 4-18, are located from 0x10000000.

See also the ARM PrimeCell System Controller (SP810) Technical Reference Manual for details of control registers in the SP810 System Controller that is in the ARM926EJ-S PXP Development Chip. See also Reset controller on page 3-22 for a description of the reset logic.

Note

All registers are 32 bits wide and do not support byte writes. Write operations must be word-wide. Bits marked as reserved in the following sections must be preserved using read-modify-write operations.

In Table 4-4 on page 4-18, the entry for Reset Level indicates the highest reset level that modifies its contents:

Level 6 This a programmable reset level that is triggered by a software reset, nSRST, P_nRST, or nPBRESET. See Reset controller on page 3-22 for a description of programmable reset levels and the reset signals.

Level 2 Pressing the SDC RECONFIG button drives the nPBSDCRECONFIG signal active and initiates reconfiguration. The registers are loaded from a writable configuration register. For example, configuration loads the OSC0 clock values from SYS_OSCRESET0. This allows the clock to be changed for testing new divider values. A hard reset of level 0 resets both the OSC0 and SYS_OSCRESET0 registers to the hard-wired default values.

Level 1 Pressing the FPGA CONFIG initiates reconfiguration of the FPGA.

Level 0 The system power on reset (nSYSPOR) is a level 0 reset and initializes all registers to their default value.

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