AHBDBGIO is a special AHB peripheral which is used mainly during verification. It’s a 32-bit output port which has no function in the implemented SoC. It is used to reflect the status of executing test cases. This register is written by the test cases and makes it easier to monitor the test case progress. The DBGIO bits are allocated as follows

• Test ID: 1st byte (Bits 0 to 7)

• Test Phase: 2nd byte (Bits 8:15)
• Test Status: Bit 16

• 0: Test is in progress
• 1: Test is done
• Test Status Code: Bit 17
• 0: Failed
• 1: Passed
• Test Timeout: Bits 18 – 31 (14 bits); the time unit is equivalent to 32 CPU cycles (Actual timeout = timeout << 5).