30.6.1 debugWire Data Register

When addressing I/O registers as data space using LD and ST instructions, the provided offset must be used. When using the I/O specific commands IN and OUT, the offset is reduced by 0x20, resulting in an I/O address offset within 0x00 - 0x3F.

The device is a complex microcontroller with more peripheral units than can be supported within the 64 locations reserved in Opcode for the IN and OUT instructions. For the extended I/O space from 0x60 in SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used.

Name: DWDR
Offset: 0x51
Reset: 0x00
Property: When addressing as I/O Register: address offset is 0x31

Bit 76543210 
 DWDR[7:0] 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 

Bits 7:0 – DWDR[7:0] debugWire Data

The DWDR Register provides a communication channel from the running program in the MCU to the debugger. This register is only accessible by the debugWIRE and can therefore not be used as a general purpose register in the normal operations.