EP2C50 datasheet(13/34 Pages) ALTERA

13 / 34 page

Chapter 1: Enhanced Configuration Devices (EPC4, EPC8, and EPC16) Data Sheet

1–13

Functional Description

Altera Corporation

Configuration Handbook (Complete Two-Volume Set)

Table 1–5 summarizes the concurrent PS configuration modes supported in the

enhanced configuration device.

f For configuration schematics and more information about concurrent configurations,

refer to the appropriate FPGA family chapter in the Configuration Handbook.

External Flash Interface

The enhanced configuration devices support external FPGA or processor access to its

flash memory. The unused portions of the flash memory can be used by the external

device to store code or data. This interface can also be used in systems that implement

remote configuration capabilities. Configuration data within a particular

configuration page can be updated via the external flash interface and the system

could be reconfigured with the new FPGA image. This interface is also useful to store

Nios boot code, application code, or both.

f For more information about the Stratix remote configuration feature, refer to the

Remote System Configuration with Stratix & Stratix GX Devices chapter in the Stratix

Device Handbook.

The address, data, and control ports of the flash memory are internally connected to

the enhanced configuration device controller and to external device pins. An external

source can drive these external device pins to access the flash memory when the flash

interface is available.

This external flash interface is a shared bus interface with the configuration controller

chip. The configuration controller is the primary bus master. Since there is no bus

arbitration support, the external device can only access the flash interface when the

controller has tri-stated its internal interface to the flash. Simultaneous access by the

controller and the external device will cause contention, and result in configuration

and programming failures.

Since the internal flash interface is directly connected to the external flash interface

pins, controller flash access cycles will toggle the external flash interface pins. The

external device must be able to tri-state its flash interface during these operations and

ignore transitions on the flash interface pins.

Table 1–5. Enhanced Configuration Devices in PS Mode

Mode Name

Mode (n =) (1)

Used Outputs

Unused Outputs

Passive serial mode

DATA0

DATA[7..1]

drive low

Multi-device passive

serial mode

DATA[1..0]

DATA[7..2]

drive low

Multi-device passive

serial mode

DATA[3..0]

DATA[7..4]

drive low

Multi-device passive

serial mode

DATA[7..0]

—

Note to Table 1–5:

(1) This is the number of valid DATA outputs for each configuration mode.

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