The control register is used to set up the debug register access by selecting the register bit size, register address (MDM command), whether an MDM or MicroBlaze™ register is accessed, and access locking. This is a write-only register. Issuing a read request to the control register generates the read acknowledgment with zero data. Writing to the register has no effect until unlocked using the DBG_LOCK register. Bit assignment in the register is described in the following tables. The register is only implemented if C_DBG_REG_ACCESS is set to 1.
| Reserved | DBG_CTRL | ||
| 31 | 20 | 19 | 0 |
| Bits | Name | Access | Reset Value | Description |
|---|---|---|---|---|
| 31-20 | Reserved | N/A | 0 | Reserved |
| 19-18 | Access Lock Type | W | 00 |
Access lock type write: 00 = Release access lock to abort atomic sequence 01 = Lock before first data access and unlock after last 10 = Lock before first data access, otherwise keep lock 11 = Force lock acquisition, even if acquired by JTAG |
| 17 | Access MDM | W | 0 |
Access MDM or MicroBlaze Debug register: 0 = MicroBlaze debug register access 1 = MDM debug register access |
| 16-9 | MDM Command | W | 0 | MDM command, see table: MDM Core User-Accessible Debug Registers. |
| 8-0 | Bit Size | W | 0 | Number of bits in the accessed debug register - 1 |