12.1.1 Cortex M0+ Configuration
| Features | Cortex M0+ options | Atmel SAM L21 configuration |
|---|---|---|
| Interrupts | External interrupts 0-32 | 29 |
| Data endianness | Little-endian or big-endian | Little-endian |
| SysTick timer | Present or absent | Present |
| Number of watchpoint comparators | 0, 1, 2 | 2 |
| Number of breakpoint comparators | 0, 1, 2, 3, 4 | 4 |
| Halting debug support | Present or absent | Present |
| Multiplier | Fast or small | Fast (single cycle) |
| Single-cycle I/O port | Present or absent | Present |
| Wake-up interrupt controller | Supported or not supported | Not supported |
| Vector Table Offset Register | Present or absent | Present |
| Unprivileged/Privileged support | Present or absent | Absent - All software run in privileged mode only |
| Memory Protection Unit | Not present or 8-region | Not present |
| Reset all registers | Present or absent | Absent |
| Instruction fetch width | 16-bit only or mostly 32-bit | 32-bit |
The ARM Cortex-M0+ core has two bus interfaces:
- Single 32-bit AMBA-3 AHB-Lite system interface that provides connections to peripherals and all system memory including Flash memory and RAM
- Single 32-bit I/O port bus interfacing to the PORT with 1-cycle loads and stores