MPC8280 datasheet(1313/1386 Pages) FREESCALE

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2C Controller

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

40-11

Table 40-7 describes the RFCR/TFCR bit fields.

40.6

I2C Commands

The I2C transmit and receive commands, shown in Table 40-8, are issued to the CP command register

(CPCR).

40.7

The I2C Buffer Descriptor (BD) Table

As shown in Figure 40-12, buffer descriptors (BDs) are organized into separate RxBD and TxBD tables

in dual-port RAM. The tables have the same basic configuration as for the SCCs and SMCs and form

circular queues that determine the order buffers are transferred. The CP uses BDs to confirm reception and

transmission or to indicate error conditions so that the core knows buffers have been serviced. The buffers

themselves can be placed in external memory or in any unused parameter area of the dual-port RAM.

Table 40-7. RFCR/TFCR Field Descriptions

Bits

Name

Description

0–1

—

Reserved, should be cleared.

GBL

Global access bit

0 Disable memory snooping

0 Enable memory snooping

3–4

Byte ordering. Selects the required byte ordering for the buffer. If BO is changed on-the-fly, 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 Big-endian

1x Munged little-endian

TC2

Transfer code 2. Contains the transfer code value of TC[2], used during this SDMA channel memory

access. TC[0–1] is driven with a 0b11 to identify this SDMA channel access as a DMA-type access.

DTB

Data bus indicator.

0 Use 60x bus for SDMA operation.

1 Use local bus for SDMA operation.

—

Reserved, should be cleared.

Table 40-8. I2C 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

2C 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.

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