TS68302VR16 datasheet(34/47 Pages) ATMEL

34 / 47 page

TS68302

2117A–HIREL–11/02

Functional

Description

The TS68302 uses a microprocessor architecture which has peripheral devices con-

nected to the system bus through a dual-port memory. Various parameters, counters,

and all memory buffer descriptor tables reside in the dual-port RAM. The receive and

transmit data buffer may be located in this on-chip RAM or in the off-chip system RAM

(see Figure 29). Six DMA channels are dedicated to the six serial ports (receive and

transmit for each of the three SCC channels). If an SCC channel’s data is programmed

to be located in the external RAM, the CP main controller (RISC processor) will program

the corresponding DMA channel to perform the required accesses. If the data resides in

the on-chip dual-port RAM, then the CP main controller accesses the RAM with one

clock cycle access and no arbitration delays.

The buffer memory structure of the TS68302 can be configured by the software to

closely match I/O channel requirements. The interrupt structure is also programmable to

relieve the on-chip 68000/68008 core from bit manipulation functions for peripherals,

allowing the processor to perform application software or protocol processing.

In some cases, the interface to equipment or proprietary networks may require the use

of standard control and data signals. For these signals, the TS68302 can be pro-

grammed to use the NMSI mode. This mode is available for one, two, or all three SCC

ports; remaining ports may then use one of the multiplexed interface modes: IDL, GCI,

or PCM.

Figure 27. Buffer Memory Structure

DUAL-PORT RAM (1152 BYTES)

TX DATA BUFFER

SCC2 BUFFER

DESCRIPTORS

TABLE

SCC1 BUFFER

DESCRIPTORS

TABLE

RX DATA

TX DATA

DATA

RX BUFFER DESCRIPTORS (8)

FRAME STATUS

DATA COUT

DATA POINTER

TX BUFFER DESCRIPTORS (8)

FRAME STATUS

DATA LENGTH

DATA POINTER

SCC3 BUFFER

DESCRIPTORS

TABLE

SCP DESCRIPTOR

SMC1 DESCRIPTOR

SMC2 DESCRIPTOR

RX DATA BUFFER

TX DATA BUFFER

EXTERNAL MEMORY

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