CDPCLK4 datasheet(220/274 Pages) ALTERA

220 / 274 page

9–62

Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family

Configuration Features

Cyclone III Device Handbook

August 2012

Altera Corporation

Volume 1

The CONFIG_IO instruction does not hold the nSTATUS pin low until reconfiguration.

You must disengage the active configuration controllers (AS and AP) by issuing the

ACTIVE_DISENGAGE

and ACTIVE_ENGAGE instructions when the active configuration is

interrupted. You must issue the ACTIVE_DISENGAGE instruction alone or prior to the

CONFIG_IO

instruction if the JTAG_PROGRAM instruction is to be issued later (Table 9–20).

This puts the active configuration controllers into the idle state. The active

configuration controller is re-engaged after user mode is reached using JTAG

programming (Table 9–20).

1 While executing the CONFIG_IO instruction, all user I/Os are tri-stated.

If reconfiguration after interruption is performed using configuration modes (rather

than using JTAG_PROGRAM), it is not necessary to issue the ACTIVE_DISENGAGE

instruction prior to CONFIG_IO. You can start reconfiguration by either pulling the

nCONFIG

pin low for at least 500 ns, or issuing the PULSE_NCONFIG instruction. If the

ACTIVE_DISENGAGE

instruction was issued and the JTAG_PROGRAM instruction fails to

enter user mode, you must issue the ACTIVE_ENGAGE instruction to reactivate the active

configuration controller. Issuing the ACTIVE_ENGAGE instruction also triggers the

reconfiguration in configuration modes; therefore, it is not necessary to pull the

nCONFIG

pin low or issue the PULSE_NCONFIG instruction.

ACTIVE_DISENGAGE

The ACTIVE_DISENGAGE instruction places the active configuration controller (AS and

AP) into an idle state prior to JTAG programming. The active configuration controller

is the AS controller when the MSEL pins are set to AS configuration scheme and the

AP controller when the MSEL pins are set to the AP configuration scheme. The two

purposes of placing the active controllers in an idle state are:

■

To ensure that they are not trying to configure the device in their respective

configuration modes during JTAG programming

ACTIVE_ENGAGE

R (2)

——

—

PULSE_NCONFIG

A (3)

—

Pulse nCONFIG pin

A (3)

—

JTAG TAP Reset

—

Notes to Table 9–19:

(1) “R” indicates that the instruction is to be executed before the next instruction, “O” indicates the optional instruction, “A” indicates that the

instruction must be executed, and “NA” indicates that the instruction is not allowed in this mode.

(2) Required if you use ACTIVE_DISENGAGE.

(3) Neither of the instruction is required if you use ACTIVE_ENGAGE.

(4) AP configuration is for Cyclone III devices only.

Table 9–19. JTAG CONFIG_IO (without JTAG_PROGRAM) Instruction Flows (1) (Part 2 of 2)

JTAG Instruction

Configuration Scheme and Current State of the Cyclone III Device Family

Prior to User Mode

(Interrupting

Configuration)

User Mode

Power Up

FPP

(4)

FPP

(4)

FPP

(4)

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