8.5.1 Stack Pointer Register Low and High byte
The SPL and SPH register pair represents the 16-bit value, SP.The low byte [7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01. For more details on reading and writing 16-bit registers, refer to Accessing 16-bit Registers.
When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. When addressing I/O Registers as data space using LD and ST instructions, 0x20 must be added to these offset addresses.
| Name: | SPL and SPH |
| Offset: | 0x5D |
| Reset: | 0x8FF |
| Property: | When addressing I/O Registers as data space the offset address is 0x3D |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| SP[11:8] | |||||||||
| Access | R | R | R | R | RW | RW | RW | RW | |
| Reset | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| SP[7:0] | |||||||||
| Access | RW | RW | RW | RW | RW | RW | RW | RW | |
| Reset | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
Bits 11:0 – SP[11:0] Stack Pointer Register
SPL and SPH are combined into SP.