Virtex-E 1.8 V Extended Memory Field Programmable Gate Arrays
DS025-2 (v3.0) March 21, 2014
Module 2 of 4
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The sequence of operations necessary to configure a
Figure 16 shows the timing of master-serial configuration.
Master-serial mode is selected by a <000> or <100> on the
mode pins (M2, M1, M0).
Table 10 shows the timing infor-
.
At power-up, VCC must rise from 1.0 V to VCC min in less
than 50 ms, otherwise delay configuration by pulling
PROGRAM Low until VCC is valid.
SelectMAP Mode
The SelectMAP mode is the fastest configuration option.
Byte-wide data is written into the FPGA with a BUSY flag
controlling the flow of data.
An external data source provides a byte stream, CCLK, a
Chip Select (CS) signal and a Write signal (WRITE). If
BUSY is asserted (High) by the FPGA, the data must be
held until BUSY goes Low.
Data can also be read using the SelectMAP mode. If
WRITE is not asserted, configuration data is read out of the
FPGA as part of a readback operation.
After configuration, the pins of the SelectMAP port can be
used as additional user I/O. Alternatively, the port can be
retained to permit high-speed 8-bit readback.
Retention of the SelectMAP port is selectable on a
design-by-design basis when the bitstream is generated. If
retention is selected, PROHIBIT constraints are required to
prevent SelectMAP-port pins from being used as user I/O.
Multiple Virtex-E FPGAs can be configured using the
SelectMAP mode, and be made to start-up simultaneously.
To configure multiple devices in this way, wire the individual
CCLK, Data, WRITE, and BUSY pins of all the devices in
parallel. The individual devices are loaded separately by
asserting the CS pin of each device in turn and writing the
appropriate data. See
Table 11 for SelectMAP Write Timing
Characteristics.
Write
Write operations send packets of configuration data into the
FPGA. The sequence of operations for a multi-cycle write
operation is shown below. Note that a configuration packet
can be split into many such sequences. The packet does
not have to complete within one assertion of CS, illustrated
1.
Assert WRITE and CS Low. Note that when CS is
asserted on successive CCLKs, WRITE must remain
Figure 15: Serial Configuration Flowchart
Apply Power
Set PROGRAM = High
Release INIT
If used to delay
configuration
Load a Configuration Bit
High
Low
FPGA makes a final
clearing pass and releases
INIT when finished.
FPGA starts to clear
configuration memory.
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Configuration Completed
End of
Bitstream?
Yes
No
Once per bitstream,
FPGA checks data using CRC
and pulls INIT Low on error.
If no CRC errors found,
FPGA enters start-up phase
causing DONE to go High.
INIT?
Figure 16: Master-Serial Mode Programming Switching Characteristics
Serial Data In
CCLK
(Output)
Serial DOUT
(Output)
1 TDSCK
2
TCKDS
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