Embedded Network Interface (ENI)

What is ENI?

• Embedded Network Interface• Originally called DPO (Digital Product Option)

card• Printer without network capability into

interface with our network card• Enable an external device with a processor to

interface the NET+ARM• The interface is used as a bridge to the LAN

More About ENI

• Allows sharing of NET+ARM’s memory system• Useful for dual processor system• Second Processor must push / pull data

– NET+ARM is a slave in ENI mode• Can use either FIFO mode or Shared Ram mode

– FIFO is fast, but have less control over data– Shared RAM is slower, but have more control– ENI must become BUS Master to use Shared

RAM• ENI is muxed with Parallel Ports (one or the other)

Hardware Concept

NetARM (Slave)

host

ENIPort

Data +AddrBus

RAM External uP System

(Master)

client

Data +AddrBus

ENI Hardware

DMA Hardware ModuleDMA Hardware Module

Transmit FIFO

Shared RAMShared RAM

External DeviceExternal Device

ENI bi-directional data bus

RAMRAM

Receive FIFO

Channel 4Channel 3

NET+ARM

ENI Hardware Peripheral

New GPIO ports on NET+50

• ENI module in GPIO mode provides four 8-bit GPIO ports

• Two ports are I/O ports (Port D and Port F) and two ports are input ports (Port G and Port H)

• GPIO port pins are individually configurable to input, output, active high interrupt or active low interrupt

• Interrupts are level sensitive

GPIO Port Interrupts on NET+50

• Port D uses interrupt 21 (ENI port 1)

• Port F uses interrupt 20 (ENI port 2)

• Port G uses interrupt 19 (ENI port 3)

• Port H uses interrupt 18 (ENI port 4)

Modes of Operation

• ENI Shared RAM – 16 bit interface

• ENI Shared RAM – 8 bit interface

• ENI FIFO – 16 interface with 8K Shared memory

• ENI FIFO – 8 interface with 8K Shared memory

Shared RAM Mode

• Allow external device (client) to random access external memory which is controlled by the the NET+ARM (host)

• 8/16-bit interface• Size of Shared RAM is can be one of the

following– 4K, 8K, 16. 32, or 64K

• Location of RAM must be a multiple of the size selected– E.g. ram size of 8k must on located on a 8k

boundary

FIFO Mode

• Data-streaming interface between the NET+ARM and the external device

• 8/16-bit interface• Two 32-byte FIFOs used to transmit and receive data• DMA 3 is used to transfer receive data from FIFO to

external memory• DMA 4 is used to transfer transmit data from external

memory to FIFO• DMA buffers must start and end on a 32-bit boundary• Data must be padded to conform to buffer requirement• 8K of shared memory can be accessed