9–52
Chapter 9: Configuration, Design Security, and Remote System Upgrades in the Cyclone III Device Family
Configuration Features
Cyclone III device family has dedicated JTAG pins that function as JTAG pins. You
can perform JTAG testing on Cyclone III device family before, during, and after
configuration. Cyclone III device family supports the BYPASS, IDCODE, and SAMPLE
instructions during configuration without interrupting configuration. All other JTAG
instructions can only be issued by first interrupting configuration and
reprogramming I/O pins using the ACTIVE_DISENGAGEand CONFIG_IOinstructions.
The CONFIG_IOinstruction allows I/O buffers to be configured using the JTAG port
and when issued after the ACTIVE_DISENGAGEinstruction interrupts configuration.
This instruction allows you to perform board-level testing prior to configuring the
Cyclone III device family or waiting for a configuration device to complete
configuration. Prior to issuing the CONFIG_IOinstruction, you must issue the
ACTIVE_DISENGAGEinstruction. This is because in Cyclone III device family, the
CONFIG_IOinstruction does not hold nSTATUSlow until reconfiguration, so you must
disengage the active configuration mode controller when active configuration is
interrupted. The ACTIVE_DISENGAGEinstruction places the active configuration mode
controllers in an idle state prior to JTAG programming. Additionally, the
ACTIVE_ENGAGEinstruction allows you to re-engage a disengaged active configuration
mode controller.
1
You must follow a specific flow when executing the CONFIG_IO, ACTIVE_DISENGAGE,
and ACTIVE_ENGAGEJTAG instructions in Cyclone III device family. For more
information about the instruction flow, refer to “JTAG Instructions” on page 9–60.
The chip-wide reset (DEV_CLRn) and chip-wide output enable (DEV_OE) pins on
Cyclone III device family do not affect JTAG boundary-scan or programming
operations. Toggling these pins does not affect JTAG operations (other than the usual
boundary-scan operation).
When designing a board for JTAG configuration, consider the dedicated configuration
pins. Table 9–16 lists how these pins must be connected during JTAG configuration.
Table 9–16. Dedicated Configuration Pin Connections During JTAG Configuration
Signal
Description
On all Cyclone III device family in the chain, nCEmust be driven low by connecting it to ground, pulling it
low using a resistor or driving it by some control circuitry. For devices that are also in multi-device AS, AP,
PS, or FPP configuration chains, the nCEpins must be connected to GND during JTAG configuration or
JTAG configured in the same order as the configuration chain.
nCE
On all Cyclone III device family in the chain, nCEOis left floating or connected to the nCEof the next
device.
nCEO
These pins must not be left floating. These pins support whichever non-JTAG configuration that is used in
production. If you only use JTAG configuration, tie these pins to GND.
MSEL[3..0]
nCONFIG
nSTATUS
Driven high by connecting to the VCCIO supply of the bank in which the pin resides and pulling up using a
resistor or driven high by some control circuitry.
Pull to the VCCIO supply of the bank in which the pin resides using a 10-k resistor. When configuring
multiple devices in the same JTAG chain, each nSTATUSpin must be pulled up to the VCCIO individually.
Pull to the VCCIO supply of the bank in which the pin resides using a 10-k resistor. When configuring
multiple devices in the same JTAG chain, each CONF_DONEpin must be pulled up to the VCCIO supply of
the bank in which the pin resides individually. CONF_DONEgoing high at the end of JTAG configuration
indicates successful configuration.
CONF_DONE
DCLK
Must not be left floating. Drive low or high, whichever is more convenient on your board.
Cyclone III Device Handbook
Volume 1
August 2012 Altera Corporation
ALTERA [ ALTERA CORPORATION ]
