Datasheet

Register Access Methods
Intel
®
Quark™ microcontroller D2000
January 2016 Datasheet
Document Number: 333577-002EN 51
5 Register Access Methods
All SoC registers are accessed as Fixed Memory Mapped Registers.
The SoC does not contain any of these traditional x86 memory register types: Fixed
IO, IO Referenced, Memory Referenced, PCI Configuration or Message Bus Registers.
5.1 Fixed Memory Mapped Register Access
Fixed Memory Mapped IO (MMIO) registers are accessed by specifying their 32-bit
address in a memory transaction from the CPU core. This allows direct manipulation of
the registers. Fixed MMIO registers are unmovable registers in memory space.
5.2 Register Field Access Types
Table 9. Register Access Types and Definitions
Access Type Meaning Description
RO Read Only In some cases, if a register is read only, writes to this
register location have no effect. However, in other cases,
two separate registers are located at the same location
where a read accesses one of the registers and a write
accesses the other register. See the I/O and memory map
tables for details.
WO Write Only In some cases, if a register is write only, reads to this
register location have no effect. However, in other cases,
two separate registers are located at the same location
where a read accesses one of the registers and a write
accesses the other register. See the I/O and memory map
tables for details.
R/W Read/Write A register with this attribute can be read and written.
R/WC Read/Write
Clear
A register bit with this attribute can be read and written.
However, a write of 1 clears (sets to 0) the corresponding
bit and a write of 0 has no effect.
R/WO Read/Write-
Once
A register bit with this attribute can be written only once
after power up. After the first write, the bit becomes read
only.
R/WLO Read/Write,
Lock-Once
A register bit with this attribute can be written to the non-
locked value multiple times, but to the locked value only
once. After the locked value has been written, the bit
becomes read only.
/P Sticky A register bit with this attribute is sticky that is it will
retain its state across warm-reset.
Reserved Reserved The value of reserved bits must never be changed.