Processor Users Manual

MOTOROLA Chapter 34. I2C Controller 34-11
Part IV. Communications Processor Module
Figure 34-11 shows the RFCR/TFCR bit Þelds.
Table 34-7 describes the RFCR/TFCR bit Þelds.
34.6 I
2
C Commands
The I
2
C transmit and receive commands, shown in Table 34-8, are issued to the CP
command register (CPCR).
Bit 0 1 2 3 4 5 6 7
Field GBL BO TC2 DTB Ñ
Reset 0000_0000
R/W R/W
Addr I2C_BASE + 04 (RFCR)/I2C_BASE + 05 (TFCR)
Figure 34-11. I
2
C Function Code Registers (RFCR/TFCR)
Table 34-7. RFCR/TFCR Field Descriptions
Bits Name Description
0Ð1 Ñ Reserved, should be cleared.
2 GBL Global access bit
0 Disable memory snooping
0 Enable memory snooping
3Ð4 BO Byte ordering. Set BO to select the required byte ordering for the buffer. If BO is changed on-the-ßy, it
takes effect at the beginning of the next frame or BD.
00 True little-endian. Note this mode can only be used with 32-bit port size memory.
01 PowerPC little-endian.
1x Big-endian.
5 TC2 Transfer code 2. Contains the transfer code value of TC[2], used during this SDMA channel memory
access. TC[0Ð1] is driven with a 0b11 to identify this SDMA channel access as a DMA-type access.
6 DTB Data bus indicator.
0 Use 60x bus for SDMA operation.
1 Use local bus for SDMA operation.
7 Ñ Reserved, should be cleared.
Table 34-8. I
2
C Transmit/Receive Commands
Command Description
INIT TX
PARAMETERS
Initializes all transmit parameters in the parameter RAM to their reset state. Should be issued only
when the transmitter is disabled. The
INIT TX AND RX PARAMETERS command can also be used to reset
both the Tx and Rx parameters.
CLOSE RXBD Forces the I
2
C controller to close the current Rx BD and use the next BD for subsequently received
data. If the controller is not receiving data, no action is taken. Use this command to extract data from a
partially full buffer.
INIT RX
PARAMETERS
Initializes all receive parameters in the parameter RAM to their reset state. Should be issued only when
the receiver is disabled. The
INIT TX AND RX PARAMETERS command can also be used to reset both the
Tx and Rx parameters.