start. Upon detecting a stop condition, the Stop Received bit in the Interrupt Flag register
(INTFLAG.PREC) will be set and the I
2
C slave will return to IDLE state.
High-Speed Mode
When the I
2
C slave is configured in High-speed mode (
Hs
, CTRLA.SPEED=0x2) and CTRLA.SCLSM=1,
switching between Full-speed and High-speed modes is automatic. When the slave recognizes a START
followed by a master code transmission and a NACK, it automatically switches to High-speed mode and
sets the High-speed status bit (STATUS.HS). The slave will then remain in High-speed mode until a
STOP is received.
10-Bit Addressing
When 10-bit addressing is enabled (ADDR.TENBITEN=1), the two address bytes following a START will
be checked against the 10-bit slave address recognition. The first byte of the address will always be
acknowledged, and the second byte will raise the address interrupt flag, see
.
If the transaction is a write, then the 10-bit address will be followed by
N
data bytes.
If the operation is a read, the 10-bit address will be followed by a repeated START and reception of '11110
ADDR[9:8]
1', and the second address interrupt will be received with the DIR bit set. The slave matches
on the second address as it it was addressed by the previous 10-bit address.
Figure 34-11. 10-bit Addressing
S
A
W
addr[7:0]
A
11110 addr[9:8]
Sr
R
S
W
S
W
11110 addr[9:8]
AMATCH INTERRUPT
AMATCH INTERRUPT
PMBus Group Command
When the PMBus Group Command bit in the CTRLB register is set (CTRLB.GCMD=1) and 7-bit
addressing is used, INTFLAG.PREC will be set when a STOP condition is detected on the bus. When
CTRLB.GCMD=0, a STOP condition without address match will not be set INTFLAG.PREC.
The group command protocol is used to send commands to more than one device. The commands are
sent in one continuous transmission with a single STOP condition at the end. When the STOP condition is
detected by the slaves addressed during the group command, they all begin executing the command they
received.
shows an example where this slave, bearing ADDRESS 1, is
addressed after a repeated START condition. There can be multiple slaves addressed before and after
this slave. Eventually, at the end of the group command, a single STOP is generated by the master. At
this point a STOP interrupt is asserted.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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