User guide

8.4 Target transfer of data

The debug communications channel is accessed by the target as coprocessor 14 on the ARM core using the ARM

instructions MCR and MRC.

Two registers are provided to transfer data:

Comms data read register

A 32-bit wide register used to receive data from the debugger. The following instruction returns

the read register value in Rd:

MRC p14, 0, Rd, c1, c0

Comms data write register

A 32-bit wide register used to send data to the debugger. The following instruction writes the value

in Rn to the write register:

MCR p14, 0, Rn, c1, c0

Caution

Refer to the ARM10 Technical Reference Manual for information on accessing DCC registers for the ARM 10. The

instructions used, positions of the status bits, and interpretation of the status bits are different for processors later

than ARM9.

Debug Communications Channel