
R8C/3GM Group
25. I2C bus Interface
R01UH0284EJ0100 Rev.1.00
Aug 09, 2011
25. I2C bus Interface
The I2C bus interface is the circuit that performs serial communication based on the data transfer format of the Philips
I2C bus.
25.1
Overview
Note:
1. All sources use one interrupt vector for I2C bus interface.
Table 25.1
I2C bus Interface Specifications
Item
Specification
Communication formats I2C bus format
- Selectable as master/slave device.
- Continuous transmit/receive operation (because the shift register, transmit
data register, and receive data register are independent.)
- Start/stop conditions are automatically generated in master mode.
- Automatic loading of the acknowledge bit during transmission
- Bit synchronization/wait function (In master mode, the state of the SCL
signal is monitored per bit and the timing is synchronized automatically. If
the transfer is not possible yet, the SCL signal goes “L” and the interface
stands by.)
- Support for direct drive of pins SCL and SDA (N-channel open-drain output)
Clock synchronous serial format
- Continuous transmit/receive operation (because the shift register, transmit
data register, and receive data register are independent.)
I/O pins
SCL (I/O): Serial clock I/O pin
SDA (I/O): Serial data I/O pin
Transfer clocks
When the MST bit in the ICCR1 register is set to 0.
External clock (input from the SCL pin)
When the MST bit in the ICCR1 register is set to 1.
Internal clock selected by bits CKS0 to CKS3 in the ICCR1 register and bits
IICTCTWI and IICTCHALF in the PINSR register (output from the SCL pin)
Receive error detection
Overrun error detection (clock synchronous serial format)
Indicates an overrun error during reception. When the last bit of the next unit
of data is received while the RDRF bit in the ICSR register is set to 1 (data in
the ICDRR register), the AL bit is set to 1.
Interrupt sources
I2C bus format .................................. 6 sources (1) Transmit data empty (including when slave address matches), end of
transmission, receive data full (including when slave address matches),
arbitration lost, NACK detection, and stop condition detection
Clock synchronous serial format ...... 4 sources
(1)Transmit data empty, end of transmission, receive data full, and overrun error
Selectable functions
I2C bus format
- Selectable output level for the acknowledge signal during reception.
Clock synchronous serial format
- MSB-first or LSB-first selectable as the data transfer direction.
SDA digital delay
- Digital delay value for the SDA pin selectable by bits SDADLY0 to
SDADLY1 in the PINSR register.