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EPC1441PC8 Datasheet, PDF (8/26 Pages) Altera Corporation – Configuration Devices for SRAM-Based LUT Devices
Page 8
Device Configuration
Figure 3 shows the basic configuration interface connections between a configuration
device chain and the Altera FPGA.
Figure 3. Altera FPGA Configured Using Two EPC1 or EPC2 Configuration Devices (1)
VCC
VCC
VCC
(3)
(2)
(3)
FPGA
DCLK
DATA0
nSTATUS
CONF_DONE
n
nCONFIG
MSEL
nCEO
N.C.
nCE
Master
Configuration
Device
DCLK
DATA
OE (3)
nCS (3) nCASC
nINIT_CONF (2)
Slave
Configuration
Device
DCLK
DATA
nCS
OE
nCASC
N.C.
GND
Notes to Figure 3:
(1) For more information about configuration interface connections, refer to the configuration chapter in the appropriate device handbook.
(2) The nINIT_CONF pin which is available on EPC2 devices has an internal pull-up resistor that is always active. This means an external pull-up
resistor is not required on the nINIT_CONF/nCONFIG line. The nINIT_CONF pin does not need to be connected if its functionality is not used.
If the nINIT_CONF pin is not used or unavailable, nCONFIG must be pulled to VCC either directly or through a resistor.
(3) EPC2 devices have internal programmable pull-up resistors on OE and nCS pins. If internal pull-up resistors are used, do not use external pull-up
resistors on these pins. The internal pull-up resistors are set by default in the Quartus II software. To turn off the internal pull-up resistors, check
the Disable nCS and OE pull-ups on configuration device option when you generate programming files.
When the first device in a configuration device chain is powered-up or reset, its nCS
pin is driven low because it is connected to the CONF_DONE pin of the FPGA. Because
both OE and nCS pins are low, the first device in the chain recognizes it as the master
device and controls configuration. Since the slave devices’ nCS pin is fed by the
previous devices’ nCASC pin, its nCS pin is high after power-up and reset. In the slave
configuration devices, the DATA output is tri-stated and DCLK is an input. During
configuration, the master device supplies the clock through DCLK to the FPGA and to
any slave configuration devices. The EPC1 or EPC2 master device also provides the
first stream of data to the FPGA during multi-device configuration. After the EPC1 or
EPC2 master device finishes sending configuration data, it tri-states its DATA pin to
avoid contention with other configuration devices. The EPC1 or EPC2 master device
also drives its nCASC pin low, which pulls the nCS pin of the next device low. This
action signals the EPC1 or EPC2 slave device to start sending configuration data to the
FPGAs.
The EPC1 or EPC2 master device clocks all slave configuration devices until
configuration is complete. When all configuration data is transferred and the nCS pin
on the EPC1 or EPC2 master device is driven high by the FPGA’s CONF_DONE pin, the
EPC1 or EPC2 master device then goes into zero-power (idle) state. The EPC2 master
device drives DATA high and DCLK low, while the EPC1 and EPC1441 device tri-state
DATA and drive DCLK low.
If the nCS pin on the EPC1 or EPC2 master device is driven high before all
configuration data is transferred, the EPC1 or EPC2 master device drives its OE signal
low, which in turn drives the FPGA’s nSTATUS pin low, indicating a configuration
error. Additionally, if the configuration device generates its data and detects that the
CONF_DONE pin has not gone high, it recognizes that the FPGA has not configured
successfully. EPC1 and EPC2 devices wait for 16 DCLK cycles after the last
Configuration Devices for SRAM-Based LUT Devices
January 2012 Altera Corporation