AT32F425
Series Reference Manual
2022.03.30
Page 115
Ver 2.01
11
I
2
C interface
11.1
I
2
C introduction
I
2
C (inter-integrated circuit) bus interface manages the communication between the microcontroller and
serial I
2
C bus. It supports master and slave modes, with up to 1 Mbit/s of communication speed
(enhanced edition).
11.2
I
2
C main features
I2C bus
―
Master and slave modes
―
Multimaster capability
―
Stand speed (100 kHz), fast speed (400 kHz) and enhanced fast speed (1 MHz)
―
7-bit and 10-bit address modes
―
Two 7-bit slave addresses (two addresses, one of them can be masked)
―
Broadcast call mode
―
Programmable data setup and hold time
―
Clock stretching capability
Support DMA transfer
Programmable digital noise filter
Support SMBus2.0 protocol
―
PEC generation and verification
―
Acknowledgement control for command and data
―
ARP(address resolution protocol)
―
Master capability
―
Device capability
―
SMBus reminder capability
―
Timeout detection
―
Idle detection
PMBus
11.3
I
2
C function overview
I
2
C bus consists of a data line (SDA) and clock line (SCL). It can achieve a maximum of 100 kHz speed
in standard mode, up to 400kHz in fast mode, up to 1 MHz in enhanced fast mode. A frame of data
transmission begins with a Start condition and ends with a Stop condition. The bus is kept in busy state
after receiving the Start condition, and becomes idle as long as it receives the Stop condition.
Start condition: SDA switches from high to low when SCL is set high.
Stop condition: SDA switches from low to high when SCL is set high.
Figure 11-1 I
2
C bus protocol
SDA
SCL
Start condition
Stop condition
8
9
2
1
MSB
ACK
3 to 7