ARM r1p3, R4, R4F

Debug

ID013010 Non-Confidential, Unrestricted Access

Software access to the DCC

Software running on the processor that sends data to the debugger through the target-to-host

channel can use the sequence of instructions that Example 11-2 shows.

Example 11-2 Target to host data transfer (target end)

; r0 -> word to send to the debugger

WriteDCC MRC p14, 0, PC, c0, c1, 0

BEQ WriteDCC

MCR p14, 0, Rd, c0, c5, 0

BX lr

Example 11-3 shows the sequence of instructions for sending data to the debugger through the

host-to-target channel.

Example 11-3 Host to target data transfer (target end)

; r0 -> word sent by the debugger

ReadDCC MRC p14, 0, PC, c0, c1, 0

BCC ReadDCC

MRC p14, 0, Rd, c0, c5, 0

BX lr

Debugger access to the DCC

When not in debug state, a debugger can access the DCC through the external interface. The

following examples show the pseudo-code operations for these accesses.

Example11-4 shows the code for target-to-host data transfer.

Example 11-4 Target to host data transfer (host end)

uint32 ReadDCC()

{

// Step 1. Poll DSCR until DTRTXfull is set to 1.

repeat

{

dscr := ReadDebugRegister(34);

}

until (dscr & (1<<29));

// Step 2. Read the value from DTRTX.

dtr_val := ReadDebugRegister(35);

return dtr_val;

}

Example11-5 shows the code for host-to-target data transfer.

Example 11-5 Host to target data transfer (host end)

WriteDCC(uint32 dtr_val)