MCF548x Reference Manual, Rev. 3
28-8 Freescale Semiconductor

28.4 Functional Description

The I2C has a simple bidirectional 2-wire bus for efficient inter-IC control. The two wires, serial data

address line (SDA) and serial clock line (SCL), carry information between the MCF548x and other devices

connected to the bus. Each device, including the MCF548x, is recognized by a unique address, and can

operate as either transmitter or receiver, depending on the function of the device. In addition to the

transmitters and receivers, devices can be considered as masters or slaves. A master is the device that

initiates a data transfer on the bus and generates the clock signals to permit that transfer. At that time, any

device addressed is considered a slave.

76543210
R0000

BNBE TE RE IE

W
Reset00010001
Reg
Addr
MBAR + 0x8F20

Figure 28-7. Interrupt Control Register

Table 28-8. I2ICR Field Descriptions

Bits Name Description
7–4 Reserved, should be cleared.
3BNBEPermits I
2C module to generate an interrupt when the bus is NOT busy. Instead of polling the bus
busy bit to see when the bus becomes free, setting BNBE bit will cause an interrupt when a STOP
is detected on the bus. Disabling this bit will prevent these interrupts. Bus NOT busy is an IDLE
condition, therefore software must clear this bit by writing a 0 to this bit position in order to clear the
interrupt. Reset condition disables this bit.
0 Disables an interrupt when the bus is stopped
1 Enables an interrupt when the bus is stopped
5-6 Reserved, should be cleared.
2 TE Routes the interrupt for the I2C module to the TX requestor at the multichannel DMA. Reset
condition disables this bit. Clear by writing a 0 to this bit position
1 RE Routes the interrupt for the I2C module to the RX requestor at the multichannel DMA. Reset
condition disables this bit. Clear by writing a 0 to this bit position.
0 IE Routes the interrupt for the I2C module to the CPU. Reset condition enables this bit. Clear by writing
a 0 to this bit position
Table 28-9. I2C Terminology
Term Description
Transmitter Device that sends the data to the bus
Receiver Device that receives the data from the bus
Master Device that initiates transfer, generates SCL and terminates transfer
Slave Device that is addressed by the master