MPC8280 datasheet(859/1386 Pages) FREESCALE

859 / 1386 page

Serial Management Controllers (SMCs)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

Freescale Semiconductor

28-5

Figure 28-3. SMC Memory Structure

The BD table allows buffers to be defined for transmission and reception. Each table forms a circular

queue. The CP uses BDs to confirm reception and transmission so that the processor knows buffers have

been serviced. The data resides in external or internal buffers.

When SMCs are configured to operate in GCI mode, their memory structure is predefined to be one

half-word long for transmit and one half-word long for receive. For more information on these half-word

structures, see Section 28.5, “The SMC in GCI Mode.”

28.2.3

SMC Parameter RAM

The CP accesses each SMC’s parameter table using a user-programmed pointer (SMCx_BASE) located in

the parameter RAM; see Section 14.5.2, “Parameter RAM.” Each SMC parameter RAM table can be

placed at any 64-byte aligned address in the dual-port RAM’s general-purpose area (banks 1–8, 11 and 12).

The protocol-specific portions of the SMC parameter RAM are discussed in the sections that follow. The

SMC parameter RAM shared by the UART and transparent protocols is shown in Table 28-2. Parameter

RAM for GCI protocol is described in Table 28-17.

Status and Control

Data Length

Buffer Pointer

Pointer to SMCx

TxBD Table

Pointer to SMCx

RxBD Table

SMC RxBD

Table

SMC TxBD

Table

Dual-Port RAM

Status and Control

Data Length

Buffer Pointer

Tx Data Buffer

External Memory

RxBD Table

TxBD Table

Rx Data Buffer

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