EP2C5T144I8N Datasheet, PDF (381/470 Pages) Altera Corporation – Cyclone II Device Handbook, Volume 1

Configuring Cyclone II Devices
Figure 13–10. Multiple Device PS Configuration Using an External Host
Memory
ADDR DATA0
External Host
(MAX II Device or
Microprocessor)
VCC (1) VCC (1)
10 kΩ 10 kΩ
GND
VCC
Cyclone II Device 1
MSEL1
MSEL0
CONF_DONE
nSTATUS
nCE
nCEO
GND
DATA0
nCONFIG
DCLK
VCC (2)
10 kΩ Cyclone II Device 2
MSEL1
MSEL0
CONF_DONE
nSTATUS
nCE
VCC
GND
DATA0
nCONFIG
DCLK
nCEO N.C. (3)
Notes to Figure 13–10:
(1) The pull-up resistor should be connected to a supply that provides an acceptable input signal for all devices in the
chain. V_CC should be high enough to meet the V_IH specification of the I/O on the devices and the external host.
(2) Connect the pull-up resistor to the V_CCIO supply voltage of I/O bank that the nCEO pin resides in.
(3) The nCEO pin can be left unconnected or used as a user I/O pin when it does not feed another device’s nCE pin.
In multiple device PS configuration, connect the first Cyclone II device’s
nCE pin to GND and connect the nCEO pin to the nCE pin of the next
Cyclone II device in the chain. Use an external 10-kΩ pull-up resistor to
pull the Cyclone II device’s nCEO pin high to its V_CCIO level to help the
internal weak pull-up resistor when the nCEO pin feeds next Cyclone II
device's nCE pin. The input to the nCE pin of the last Cyclone II device in
the chain comes from the previous Cyclone II device. After the first
device completes configuration in a multiple device configuration chain,
its nCEO pin transitions low to activate the second device’s nCE pin,
which prompts the second device to begin configuration. The second
device in the chain begins configuration within one clock cycle.
Therefore, the MAX II device begins to transfer data to the next Cyclone II
device without interruption. The nCEO pin is a dual-purpose pin in
Cyclone II devices. 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 Cyclone II device.
1
The Quartus II software sets the Cyclone II device nCEO pin as a
dedicated output by default. If the nCEO pin feeds the next
device’s nCE pin, you must make sure that the nCEO pin is not
used as a user I/O after configuration. This software setting is in
the Dual-Purpose Pins tab of the Device & Pin Options dialog
box in Quartus II software.
Altera Corporation
February 2007
13–27
Cyclone II Device Handbook, Volume 1