DocID025202 Rev 7
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RM0365
Inter-integrated circuit (I2C) interface
834
28.7 I2C
registers
for a list of abbreviations used in register descriptions.
The peripheral registers are accessed by words (32-bit).
28.7.1
Control register 1 (I2C_CR1)
Address offset: 0x00
Reset value: 0x0000 0000
Access: No wait states, except if a write access occurs while a write access to this register is
ongoing. In this case, wait states are inserted in the second write access until the previous
one is completed. The latency of the second write access can be up to 2 x PCLK1 + 6 x
I2CCLK.
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Res.
Res.
Res.
Res.
Res.
Res.
Res.
Res.
PECEN
ALERT
EN
SMBD
EN
SMBH
EN
GCEN
WUPE
N
NOSTR
ETCH
SBC
rw
rw
rw
rw
rw
rw
rw
rw
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RXDMA
EN
TXDMA
EN
Res.
ANF
OFF
DNF
ERRIE
TCIE
STOP
IE
NACK
IE
ADDR
IE
RXIE
TXIE
PE
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
Bits 31:24 Reserved, must be kept at reset value.
Bit 23
PECEN:
PEC enable
0: PEC calculation disabled
1: PEC calculation enabled
Note: If the SMBus feature is not supported, this bit is reserved and forced by hardware to ‘0’.
Section 28.3: I2C implementation
Bit 22
ALERTEN
: SMBus alert enable
Device mode (SMBHEN=0)
:
0: Releases SMBA pin high and Alert Response Address Header disabled: 0001100x
followed by NACK.
1: Drives SMBA pin low and Alert Response Address Header enables: 0001100x followed
by ACK.
Host mode (SMBHEN=1)
:
0: SMBus Alert pin (SMBA) not supported.
1: SMBus Alert pin (SMBA) supported.
Note: When ALERTEN=0, the SMBA pin can be used as a standard GPIO.
If the SMBus feature is not supported, this bit is reserved and forced by hardware to ‘0’.
Please refer to
Section 28.3: I2C implementation
Bit 21
SMBDEN
: SMBus Device Default address enable
0: Device default address disabled. Address 0b1100001x is NACKed.
1: Device default address enabled. Address 0b1100001x is ACKed.
Note: If the SMBus feature is not supported, this bit is reserved and forced by hardware to ‘0’.