I2C Controller
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 39-13

Table39-9 describes I2C RxBD status and control bits.

39.7.1.2 I2C Transmit Buffer Descriptor (TxBD)

Transmit data is arranged in buffers referenced by TxBDs in the TxBD table. T he first word of the TxBD,

shown in Figure 39-14, contains status and control bits.

012345 131415
Offset + 0 EWIL—OV
Offset + 2 Data Length
Offset + 4 RX Buffer Pointer
Offset + 6

Figure 39-13. I2C RxBD

Table39-9. I2C RxBD Status and Control Bits

Bits Name Description
0EEmpty.
0 The buffer is full or stopped receiving because of an error. The core can examine or write to any
fields of this RxBD, but the CP does not use this BD while E = 0.
1 The buffer is empty or reception is in progress. The CP owns this RxBD and its buffer. Once E is
set, the core should not write any fields of this RxBD.
1 Reserved and should be cleared.
2WWrap (last BD i n table).
0 Not the last BD in the RxBD table.
1 Last BD in the RxBD table. After this buffer is used, the CP receives incoming data using the BD
pointed to by RBASE (top of the table). The number of BDs in this table is determined only by the
W bit and overall space constraints of the dual-port RAM.
3IInterrupt.
0 No interrupt is generated after this buffer is full.
1 The I2CER[RXB] is set when the CP fills this buffer, indicating that the core needs to process the
buffer. The RXB bit can cause an interrupt if it is enabled.
4 L Last. The I2C controller sets L.
0 This buffer does not contain the last character of the message.
1 This buffer holds the last character of the message. The I2C controller sets L after all received
data is placed into the associated buffer, or because of a stop or start condition or an overrun.
5–13 Reserved and should be cleared.
14 OV Overrun. Set when a receiver overrun occurs during reception. The I2C controller updates this bit
after the received data is placed into the associated buffer.
15 Reserved and should be cleared.