Symbol
Description
GHz
10
9
= 1,000,000,000Hz
s
second
ms
millisecond
µs
microsecond
ns
nanosecond
50.4. Registers and Bits
Table 50-3. Register and Bit Mnemonics
Symbol
Description
R/W
Read/Write accessible register bit. The user can read from and write to this bit.
R
Read-only accessible register bit. The user can only read this bit. Writes will be
ignored.
W
Write-only accessible register bit. The user can only write this bit. Reading this bit will
return an undefined value.
BIT
Bit names are shown in uppercase. (Example ENABLE)
FIELD[n:m]
A set of bits from bit n down to m. (Example: PINA[3:0] = {PINA3, PINA2, PINA1,
PINA0}
Reserved
Reserved bits are unused and reserved for future use. For compatibility with future
devices, always write reserved bits to zero when the register is written. Reserved bits
will always return zero when read.
PERIPHERAL
i
If several instances of a peripheral exist, the peripheral name is followed by a number
to indicate the number of the instance in the range 0-n. PERIPHERAL0 denotes one
specific instance.
Reset
Value of a register after a power reset. This is also the value of registers in a peripheral
after performing a software reset of the peripheral, except for the Debug Control
registers.
SET/CLR
Registers with SET/CLR suffix allows the user to clear and set bits in a register without
doing a read-modify-write operation. These registers always come in pairs. Writing a
one to a bit in the CLR register will clear the corresponding bit in both registers, while
writing a one to a bit in the SET register will set the corresponding bit in both registers.
Both registers will return the same value when read. If both registers are written
simultaneously, the write to the CLR register will take precedence.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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