2023年12月20日发(作者：进口奥迪a6)

Active Serial Configuration (Serial Configuration Devices)fFor more information on configuration issues, see the Debugging

Configuration Problems chapter of the Configuration Handbook and the

FPGA Configuration Troubleshooter on the Altera web site

().Multiple Device AS ConfigurationYou can configure multiple CycloneII devices using a single serial

configuration device. You can cascade multiple CycloneII devices using

the chip-enable (nCE) and chip-enable-out (nCEO) pins. Connect the nCE

pin of the first device in the chain to ground and connect the nCEO pin to

the nCE pin of the next device in the chain. Use an external 10-kΩ pull-up

resistor to pull the nCEO signal high to its VCCIO level to help the internal

weak pull-up resistor. When the first device captures all of its

configuration data from the bitstream, it transitions its nCEO pin low,

initiating the configuration of the next device in the chain. You can leave

the nCEO pin of the last device unconnected or use it as a user I/O pin

after configuration if the last device in chain is a CycloneII device.

1The QuartusII software sets the CycloneII device nCEO pin as

an output pin driving to ground by default. If the device is in a

chain, and the nCEO pin is connected to the next device’s nCE

pin, you must make sure that the nCEO pin is not used as a user

I/O pin after configuration. The software setting is in the

Dual-Purpose Pins tab of the Device & Pin Options dialog box

in QuartusII first CycloneII device in the chain is the configuration master and

controls the configuration of the entire chain. Select the AS configuration

scheme for the first CycloneII device and the PS configuration scheme for

the remaining CycloneII devices (configuration slaves). Any other

Altera? device that supports PS configuration can also be part of the chain

as a configuration slave. In a multiple device chain, the nCONFIG,

nSTATUS, CONF_DONE, DCLK, and DATA0 pins of each device in the chain

are connected (see Figure13–4). Figure13–4 shows the pin connections

for this e II Device Handbook, Volume 1

PS ConfigurationYou must connect all other configuration pins (nCONFIG, nSTATUS,

DCLK, DATA0, and CONF_DONE) to every CycloneII device in the chain.

The configuration signals may require buffering to ensure signal integrity

and prevent clock skew problems. You should buffer the DCLK and DATA

lines for every fourth device. Because all device CONF_DONE pins are tied

together, all devices initialize and enter user mode at the same all nSTATUS and CONF_DONE pins are connected, if any CycloneII

device detects an error, configuration stops for the entire chain and the

entire chain must be reconfigured. For example, if the first CycloneII

detects an error, it resets the chain by pulling its nSTATUS pin low. This

behavior is similar to a single CycloneII device detecting an the Auto-restart configuration after error option is turned on, the

CycloneII devices release their nSTATUS pins after a reset time-out

period (maximum of 40 ?s). After all nSTATUS pins are released and

pulled high, the MAXII device reconfigures the chain without pulsing

nCONFIG low. If the Auto-restart configuration after error option is

turned off, the MAXII device must generate a low-to-high transition

(with a low pulse of at least 2 ?s) on nCONFIG to restart the configuration

you want to delay the initialization of the devices in the chain, you can

use the CLKUSR pin option. The CLKUSR pin allows you to control when

your device enters user mode. This feature also allows you to control the

order of when each device enters user mode by feeding a separate clock

to each device’s CLKUSR pin. By using the CLKUSR pins, you can choose

any device in the multiple device chain to enter user mode first and have

the other devices enter user mode at a later ent device families may require a different number of initialization

clock cycles. Therefore, if your multiple device chain consists of devices

from different families, the devices may enter user mode at a slightly

different time due to the different number of initialization clock cycles

required. However, if the number of initialization clock cycles is similar

across different device families or if the devices are from the same family,

then the devices enter user mode at the same time. See the respective

device family handbook for more information about the number of

initialization clock cycles e II Device Handbook, Volume 1

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