EP2AGX95EF29C6N Datasheet, PDF (323/380 Pages) Altera Corporation – Device Interfaces and Integration

Chapter 9: Configuration, Design Security, and Remote System Upgrades in Arria II Devices
JTAG Configuration
9–37
You must connect the nCE pin to GND or drive it low during JTAG configuration. In
multi-device FPP, AS, and PS configuration chains, the nCE pin of the first device is
connected to GND, while its nCEO pin is connected to nCE of the next device in the
chain. The nCE input of the last device comes from the previous device, while its nCEO
pin is left floating. In addition, the CONF_DONE and nSTATUS signals are all shared in
multi-device FPP, AS, or PS configuration chains so the devices can enter user mode at
the same time after configuration is complete. When the CONF_DONE and nSTATUS
signals are shared among all the devices, you must configure every device when JTAG
configuration is performed.
1 If you only use JTAG configuration, Altera recommends connecting the circuitry as
shown in Figure 9–17, where each of the CONF_DONE and nSTATUS signals are isolated to
enable each device to enter user mode individually.
After the first device completes configuration in a multi-device configuration chain,
its nCEO pin drives low to activate the nCE pin of the second device, which prompts the
second device to begin configuration. Therefore, if these devices are also in a JTAG
chain, ensure the nCE pins are connected to GND during JTAG configuration or that
the devices are JTAG configured in the same order as the configuration chain. As long
as the devices are JTAG configured in the same order as the multi-device
configuration chain, the nCEO of the previous device drives the nCE of the next device
low when it has successfully been JTAG configured.
You can place other Altera devices that have JTAG support in the same JTAG chain for
device programming and configuration.
1 JTAG configuration support is enhanced and allows more than 17 Arria II devices to
be cascaded in a JTAG chain.
f For more information about configuring multiple Altera devices in the same
configuration chain, refer to the Configuring Mixed Altera Device Chains chapter in
volume 2 of the Configuration Handbook.
You can configure Arria II devices using multiple configuration schemes on the same
board. Combining JTAG configuration with a PS or AS configuration on your board is
useful in the prototyping environment because it allows multiple methods to
configure your FPGA.
f For more information about combining JTAG configuration with other configuration
schemes, refer to the Combining Different Configuration Schemes chapter in volume 2 of
the Configuration Handbook.
July 2012 Altera Corporation
Arria II Device Handbook Volume 1: Device Interfaces and Integration