====== ARM Cortex-M 0+ ======

===== Memory Map =====
^ start address ^ end address ^ used for ^ comment ^
| 0x00 00 00 00 | 0x1F FF FF FF | **Code** | |
| 0x20 00 00 00 | 0x3F FF FF FF | **SRAM** | |
| 0x40 00 00 00 | 0x5F FF FF FF | **Peripheral** | |
| 0x60 00 00 00 | 0x7F FF FF FF | **RAM** | |
| 0x80 00 00 00 | 0x9F FF FF FF | **RAM** | |
| 0xA0 00 00 00 | 0xBF FF FF FF | **Device** | |
| 0xC0 00 00 00 | 0xDF FF FF FF | **Device** | |
| 0xE0 00 00 00 | 0xFF FF FF FF | **System** | |
| 0xE0 00 00 00 | 0xE0 0F FF FF | **PPB** | Private Peripheral Bus |
| 0xE0 00 10 00 | 0xE0 00 1F FF | Data Watchpoint and Trace | |
| 0xE0 00 10 00 |  | DWT_CTRL | |
| 0xE0 00 10 1C |  | DWT_PCSR | Program Counter Sample Register |
| 0xE0 00 10 20 |  | DWT_COMPx | Comparator registers |
| 0xE0 00 10 24 |  | DWT_MASKx | Comparator Mask Registers |
| 0xE0 00 10 28 |  | DWT_FUNCTIONx | Comparator Function Registers |
| 0xE0 00 20 00 | 0xE0 00 2F FF | Breakpoint unit | |
| 0xE0 00 20 00 |  | BP_CTRL | |
| 0xE0 00 20 08 |  | BP_COMPx | Breakpoint Comparator registers |
| 0xE0 00 E0 00 | 0xE0 00 EF FF | **System Control Space** | |
| 0xE0 00 E0 08 | 0xE0 00 E0 0F | **System Control Block** | |
| 0xE0 00 E0 08 |  | ACTLR | Auxiliary Control Register |
| 0xE0 00 E0 10 | 0xE0 00 E0 FF | **SysTick** | optional |
| 0xE0 00 E0 10 |  | SYST_CSR | SysTick Control and Status Register |
| 0xE0 00 E0 14 |  | SYST_RVR | SysTick Reload Value Register |
| 0xE0 00 E0 18 |  | SYST_CVR | SysTick Current Value Register |
| 0xE0 00 E0 1C |  | SYST_CALIB | SysTick Calibration Value Register |
| 0xE0 00 E1 00 | 0xE0 00 EC FF | **Nested Vectored Interrupt Controller** | |
| 0xE0 00 E1 00 |  | NVIC_ISER | Interrupt Set-Enable Register |
| 0xE0 00 E1 80 |  | NVIC_ICER | Interrupt Clear-Enable Register |
| 0xE0 00 E2 00 |  | NVIC_ISPR | Interrupt Set-Pending Register |
| 0xE0 00 E2 80 |  | NVIC_ICPR | Interrupt Clear-Pending Register |
| 0xE0 00 E4 00 | 0xE0 00 E4 EF | NVIC_IPRO0-7 | Interrupt Priority Registers |
| 0xE0 00 ED 00 | 0xE0 00 ED 8F | **System Conrol Block** | |
| 0xE0 00 ED 00 |  | CPUID | |
| 0xE0 00 ED 04 |  | ICSR | Interrupt Control and State Register |
| 0xE0 00 ED 08 |  | VTOR | Vector Table Offset Register (optional) |
| 0xE0 00 ED 0C |  | AIRCR | Application Interrupt and Reset Control Register |
| 0xE0 00 ED 10 |  | SCR | System Control Register |
| 0xE0 00 ED 14 |  | CCR | Configuration and Control Register |
| 0xE0 00 ED 1C |  | SHPR2 | System Handler Priority Register 2 |
| 0xE0 00 ED 20 |  | SHPR3 | System Handler Priority Register 3 |
| 0xE0 00 ED 24 |  | SHCSR | System Handler Control and State Register |
| 0xE0 00 ED 30 |  | DFSR | Debug Fault Status Register |
| 0xE0 00 ED 90 | 0xE0 00 ED EF | **Memory Protection Unit** | optional |
| 0xE0 00 ED 90 |  | MPU_TYPE |  |
| 0xE0 00 ED 94 |  | MPU_CTRL | MPU Control Register |
| 0xE0 00 ED 98 |  | MPU_RNR | MPU Region Number Register |
| 0xE0 00 ED 9C |  | MPU_RBAR | MPU Region Base Address Register |
| 0xE0 00 ED A0 |  | MPU_RASR | MPU Region Attribute and Size Register |
| 0xE0 00 ED F0 | 0xE0 00 EE FF | **Debug Control Block** | |
| 0xE0 00 ED F0 |  | [[arm:cortex_m0p#DHCSR - Debug Halting Control and Status Register|DHCSR]] | Debug Halting Control and Status |
| 0xE0 00 ED F4 |  | DCRSR | Debug Core Register Selector Register |
| 0xE0 00 ED F8 |  | DCRDR | Debug Core Register Data Register |
| 0xE0 00 ED FC |  | DEMCR | Debug Exception and Monitor Control Register |
| 0xE0 00 EF 00 | 0xE0 00 EF 03 | **Nested Vectored Interrupt Controller** | |
| 0xE0 00 EF 90 | 0xE0 00 EF CF | implementation defined | |
| 0xE0 0F F0 00 | 0xE0 0F FF FF | **[[arm:cortex_m0p#ROM Table|ARMv6-M ROM table]]** | |
| 0xE0 10 00 00 | 0xFF FF FF FF | **Vendor_SYS** | |

==== ROM Table ====

^ offset ^ name ^ value ^ description ^
| 0x000 | SCS | 0xFF F0 F0 03 | Points to the System Control Space(SCS) at 0xE0 00 E0 00 |
| 0x004 | ROMDWT | 0xFF F0 20 02 or 0xFF F0 20 03 | points to the Data Watchpoint and Trace(DWT) at 0xE0 00 10 00 |
| 0x008 | ROMBPU | 0xFF F0 30 02 or 0xFF F0 30 03 | points to the Breakpoint unit(BPU) at 0xE0 00 20 00 |
| 0x00C | End | 0x00 00 00 00 | End of table marker. |
| 0x010 - 0xffc | reserved | 0x00 00 00 00 | reserved (read as 0) |

each entry (32bit) adheres to this format:
^ bits ^ name ^ description ^
| 31 - 12 | address offset | signed base address offset of the component relative to the ROM base address |
| 11 - 2 | reserved | |
| 1 | format | 0 = 8 bit (not used) ; 1 = 32 bit |
| 0 | entry present | 1 = valid entry; 0 = entry not valid or end of table |


==== DHCSR - Debug Halting Control and Status Register ====

write:
^ bits ^ name ^ description ^
| 31 - 16 | DBGKEY | must be 0xa05f |
| 15 - 4 | reserved | |
| 3 | C_MASKINTS | 0 = do not mask; 1 = mask PendSV, SysTick and external configurable interrupts |
| 2 | C_STEP | 0 = single stepping disabled; 1 = single stepping enabled |
| 1 | C_HALT | 0 = request a halted processor to run; 1 = request a running processor to halt |
| 0 | C_DEBUGEN | 0 = halting debug disabled; 1 = halting debug enabled |

read:
^ bits ^ name ^ description ^
| 31 - 26 | reserved | |
| 25 | S_RESET_ST | 0 = no processor reset since last DHCSR read; 1 = at least one processor reset since last read of DHCSR |
| 24 | S_RETIRE_ST | 0 = no instruction executed since last read of DHCSR; 1 = at least one instruction executed since last read of DHCSR |
| 23 - 20 | reserved | |
| 19 | S_LOOKUP | 0 = no lookup; 1 = processor in unrecoverable exception |
| 18 | S_SLEEP | 0 = not sleeping; 1 = sleeping|
| 17 | S_HALT | 0 = not in debug state; 1 = in debug state |
| 16 | S_REGRDY | 0 = write to DCRDR but transfer is not complete; 1 = the transfer to/from DCRDR is complete |
| 15 - 4 | reserved | |
| 3 | C_MASKINTS | 0 = do not mask; 1 = mask PendSV, SysTick and external configurable interrupts |
| 2 | C_STEP | 0 = single stepping disabled; 1 = single stepping enabled |
| 1 | C_HALT | 0 = request a halted processor to run; 1 = request a running processor to halt |
| 0 | C_DEBUGEN | 0 = halting debug disabled; 1 = halting debug enabled |