PXD10RM Datasheet, PDF (743/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

begin. For instance, if the I²C is configured for master transmit but a master receive is desired, then reading
the IBDR will not initiate the receive.
Reading the IBDR will return the last byte received while the I²C is configured in either master receive or
slave receive modes. The IBDR does not reflect every byte that is transmitted on the I²C bus, nor can
software verify that a byte has been written to the IBDR correctly by reading it back.
In master transmit mode, the first byte of data written to the IBDR following assertion of MS/SL is used
for the address transfer and should comprise the calling address (in position D7–D1) concatenated with
the required R/W bit (in position D0).
20.4.3.6 I²C Bus Interrupt Configuration Register
Offset 0x0005
Access: Read/write any time
0
1
2
3
4
5
6
7
R BIIE
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
0
0
0
Figure 20-10. I²C Bus Interrupt Configuration Register (IBIC)
Table 20-10. IBIC Field Descriptions
Field
Description
BIIE Bus Idle Interrupt Enable bit. This config bit can be used to enable the generation of an interrupt once the
I²C bus becomes idle. Once this bit is set, an IBB high-low transition will set the IBIF bit. This feature can
be used to signal to the CPU the completion of a STOP on the I²C bus.
1 Bus Idle Interrupts enabled
0 Bus Idle Interrupts disabled
20.5 Functional description
20.5.1 General
This section provides a complete functional description of the Inter-Integrated Circuit (I²C).
20.5.2 I-Bus Protocol
The I²C Bus system uses a Serial Data line (SDA) and a Serial Clock Line (SCL) for data transfer. All
devices connected to it must have open drain or open collector outputs. A logical AND function is
exercised on both lines with external pull-up resistors. The value of these resistors is system dependent.
Normally, a standard communication is composed of four parts: START signal, slave address transmission,
data transfer and STOP signal. They are described briefly in the following sections and illustrated in
Figure 20-11.
Freescale Semiconductor
PXD10 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
20-13