ARM7TDMI-S Technical Reference Manual 5.24. Debug control register

5.24. Debug control register

The debug control register is six bits wide. Writes to the debug control register occur when a watchpoint unit register is written. Reads of the debug control register occur when a watchpoint unit register is read. See Watchpoint unit registers for more information.

Figure 5.15 shows the function of each bit in the debug control register.

Figure 5.15. Debug control register format

The debug control register bit assignments are shown in Table 5.7.

Table 5.7. Debug control register bit assignments

Bit	Function
5	Used to disable the EmbeddedICE-RT comparator outputs while the watchpoint and breakpoint registers are being programmed. This bit can be read and written through JTAG. Set bit 5 when: programming breakpoint or watchpoint registers changing bit 4 of the debug control register. You must clear bit 5 after you have made the changes, to re-enable the EmbeddedICE-RT logic and make the new breakpoints and watchpoints operational.
4	Used to determine the behavior of the core when breakpoints or watchpoints are reached: If clear, the core enters debug state when a breakpoint or watchpoint is reached. If set, the core performs an abort exception when a breakpoint or watchpoint is reached. This bit can be read and written from JTAG.
3	This bit must be clear.
2	Used to disable interrupts: If set, the interrupt enable signal of the core (IFEN) is forced LOW. The IFEN signal is driven as shown in Table 5.8. If clear, interrupts are enabled.
1	Used to force the value on DBGRQ.
0	Used to force the value on DBGACK.

Copyright © 2001 ARM Limited. All rights reserved.	ARM DDI 0234B
Non-Confidential
PDF version