Virtex-E 1.8 V Field Programmable Gate Arrays
R
Module 2 of 4
DS022-2 (v3.0) March 21, 2014
14
Production Product Specification
— OBSOLETE — OBSOLETE — OBSOLETE — OBSOLETE —
.
Master-Serial Mode
In master-serial mode, the CCLK output of the FPGA drives
a Xilinx Serial PROM that feeds bit-serial data to the DIN
input. The FPGA accepts this data on each rising CCLK
edge. After the FPGA has been loaded, the data for the next
device in a daisy-chain is presented on the DOUT pin after
the rising CCLK edge. The maximum capacity for a single
LOUT/DOUT write is 220-1 (1,048,575) 32-bit words, or
33,554,4000 bits.
The interface is identical to slave-serial except that an inter-
nal oscillator is used to generate the configuration clock
(CCLK). A wide range of frequencies can be selected for
CCLK, which always starts at a slow default frequency. Con-
figuration bits then switch CCLK to a higher frequency for
the remainder of the configuration. Switching to a lower fre-
quency is prohibited.
The CCLK frequency is set using the ConfigRate option in
the bitstream generation software. The maximum CCLK fre-
quency that can be selected is 60 MHz. When selecting a
CCLK frequency, ensure that the serial PROM and any
daisy-chained FPGAs are fast enough to support the clock
rate.
On power-up, the CCLK frequency is approximately
2.5 MHz. This frequency is used until the ConfigRate bits
have been loaded when the frequency changes to the
selected ConfigRate. Unless a different frequency is speci-
fied in the design, the default ConfigRate is 4 MHz.
In a full master/slave system (
Figure 13), the left-most
device operates in master-serial mode. The remaining
devices operate in slave-serial mode. The SPROM RESET
pin is driven by INIT, and the CE input is driven by DONE.
There is the potential for contention on the DONE pin,
depending on the start-up sequence options chosen.
The sequence of operations necessary to configure a
Figure 13: Master/Slave Serial Mode Circuit Diagram
VIRTEX-E
MASTER
SERIAL
VIRTEX-E,
XC4000XL,
SLAVE
XC1701L
PROGRAM
M2
M0 M1
DOUT
CCLK
CLK
3.3V
DATA
CE
CEO
RESET/OE
DONE
DIN
INIT
DONE
PROGRAM
CCLK
DIN
DOUT
M2
M0 M1
(Low Reset Option Used)
330
Ω
XCVE_ds_013_050103
N/C
Note 1: If none of the Virtex FPGAs have been selected to drive DONE, an external pull-up resistor
of 330
Ω should be added to the common DONE line. (For Spartan-XL devices, add a 4.7K Ω
pull-up resistor.) This pull-up is not needed if the DriveDONE attribute is set. If used,
DriveDONE should be selected only for the last device in the configuration chain.
Optional Pull-up
Resistor on Done
1
Figure 14: Slave-Serial Mode Programming Switching Characteristics
4 TCCH
3 TCCO
5 TCCL
2 TCCD
1 TDCC
DIN
CCLK
DOUT
(Output)
X5379_a