Figure 34-5. I
2
C Master Behavioral Diagram (SCLSM=1)
IDLE
S
BUSY
BUSY
P
Sr
P
M3
M3
M2
M2
M1
M1
R
DATA
W
A/A
DATA
APPLICATION
SW
SW
Sr
P
M3
M2
BUSY
M4
SW
A/A
M4
A
IDLE
IDLE
MB INT SCL HOLD
SW
SW
SW
BUSY
R/W
A
A
R/W
BUSY
M4
SW
Software interaction
The master provides data on the bus
Addressed slave provides data on the bus
SB INT SCL HOLD
Wait for
IDLE
ADDRESS
Master Clock Generation
The SERCOM peripheral supports several I
2
C bi-directional modes:
•
Standard mode (
Sm
) up to 100kHz
•
Fast mode (
Fm
) up to 400kHz
•
Fast mode Plus (
Fm+
) up to 1MHz
•
High-speed mode (
Hs
) up to 3.4MHz
The Master clock configuration for
Sm, Fm,
and
Fm+
Clock Generation (Standard-Mode,
Fast-Mode, and Fast-Mode Plus)
Hs
Master Clock Generation (High-Speed Mode)
.
Clock Generation (Standard-Mode, Fast-Mode, and Fast-Mode Plus)
In I
2
C
Sm, Fm
, and
Fm+
mode, the Master clock (SCL) frequency is determined as described in this
section:
The low (T
LOW
) and high (T
HIGH
) times are determined by the Baud Rate register (BAUD), while the rise
(T
RISE
) and fall (T
FALL
) times are determined by the bus topology. Because of the wired-AND logic of the
bus, T
FALL
will be considered as part of T
LOW
. Likewise, T
RISE
will be in a state between T
LOW
and T
HIGH
until a high state has been detected.
Atmel SAM L22G / L22J / L22N [DATASHEET]
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