AT32F421
Series Reference Manual
2022.11.11
Page 126
Rev 2.02
recognized.
11.5.5 Data register (I2C_DT)
Bit
Register
Reset value
Type
Description
Bit 15: 8
Reserved
0x00
resd
Kept at its default value
Bit 7: 0
DT[7: 0]
0x00
rw
This field is used to store data received or to be
transferred.
Transmitter mode: Data transfer starts automatically when
a byte is written to the DT register. Once the transfer starts
(TDE=1), I
2
C will keep a continuous data transfer flow if
the next data to be transferred is written to the DT register
in a timely manner.
Receiver mode: Bytes received are copied into the DT
register (RDNE=1). A continuous data transfer flow can be
maintained if the DT register is read before the next word
is received (RDNE=1).
Note: If an ARLOST event occurs on ACK pulse, the
received byte is not copied into the data register, so it
cannot be read.
11.5.6 Status register1 (I2C_STS1)
Bit
Register
Reset value
Type
Description
Bit 15
ALERTF
0x0
rw0c
SMBus alert flag
In SMBus host mode:
0: No SMBus alert
1: SMBus alert event is received.
In SMBus slave mode:
It indicates the receiving status of the default device
address (0001100x)
0: Default device address is not received.
1: Default device address is received.
This bit is cleared by software, or by hardware when
I2CEN=0.
Bit 14
TMOUT
0x0
rw0c
SMBus timeout flag
0: No timeout error.
1: Timeout
This bit is cleared by software, or by hardware when
I2CEN=0.
Note: This function is valid only in SMBUS mode.
Bit 13
Reserved
0x0
resd
Kept at its default value.
Bit 12
PECERR
0x0
rw0c
PEC receive error flag
0: No PEC error
1: PEC error occurs.
This bit is cleared by software.
Bit 11
OUF
0x0
rw0c
Overload / underload flag
In transmission mode:
0: Normal
1: Underload
In reception mode:
0: Normal
1: Overload
This bit is cleared by software, or by hardware when
I2CEN=0.
Bit 10
ACKFAIL
0x0
rw0c
Acknowledge failure flag
0: No acknowledge failure