64.6.7 SECUMOD JTAG Protection Control Register
Note: Reset values are all 0 when fuse DEFDBG is programmed.
| Name: | SECUMOD_JTAGCR |
| Offset: | 0x0068 |
| Reset: | 0x00000008 |
| Property: | Read/Write |
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| Access | |||||||||
| Reset |
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| Access | |||||||||
| Reset |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| Access | |||||||||
| Reset |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| WZO | CA5_DEBUG_MODE[2:0] | FNTRST | |||||||
| Access | R/W | R/W | R/W | R/W | R/W | ||||
| Reset | 0 | 1 | 0 | 0 | 0 | ||||
Bit 4 – WZO Write ZERO
Must be written with 0.
Bits 3:1 – CA5_DEBUG_MODE[2:0] Invasive/Non-Invasive Secure/Non-Secure Debug Permissions
This field is used to set different debug permission levels. For instance, it can be used to prevent debug on secure parts of the code. The table below shows the effect of the field value on the Cortex-A5 pins (SPIDEN, DBGEN, SPNIDEN and NIDEN).
| CA5_DEBUG_MODE Value | Debug Permissions | SPIDEN | DBGEN | SPNIDEN | NIDEN |
|---|---|---|---|---|---|
| b000 | No Debug | 0 | 0 | 0 | 0 |
| b001 | Non-Invasive, Non-Secure | 0 | 0 | 0 | 1 |
| b010 | Full Non-Secure (Invasive and Non-Invasive) | 0 | 1 | 0 | 0 |
| b011 | Full Non-Secure + Non-Invasive Secure | 0 | 1 | 1 | 1 |
| b100 | Full Debug allowed | 1 | 1 | 1 | 1 |
Bit 0 – FNTRST Force NTRST
| Value | Description |
|---|---|
| 0 | The Arm processor’s TAP controller access and boundary JTAG are not blocked by the Security Module. |
| 1 | nDBGRESET of the processor’s TAP controller and boundary JTAG reset are held low, preventing the processor to switch to debug state and boundary JTAG to work. |