R
Spartan-IIE FPGA Family: Functional Description
Table 11: Configuration Modes
Preconfiguration
CCLK
Configuration Mode
Pull-ups
M0
0
M1
0
M2
0
Direction
Data Width
Serial DOUT
Master Serial mode
No
Out
1
Yes
Yes
Yes
No
0
0
1
Slave Parallel mode
(SelectMAP)
0
1
0
In
8
1
1
No
No
0
1
1
Boundary-Scan mode
Slave Serial mode
Notes:
Yes
No
1
0
0
N/A
In
1
0
1
Yes
No
1
1
0
Yes
1
1
1
1. During power-on and throughout configuration, the I/O drivers will be in a high-impedance state. After configuration, all unused I/Os
(those not assigned signals) will remain in a high-impedance state. Pins used as outputs may pulse High at the end of configuration
(see Answer 10504).
2. If the Mode pins are set for preconfiguration pull-ups, those resistors go into effect once the rising edge of INIT samples the Mode
pins. They will stay in effect until GTS is released during startup, after which the UnusedPin bitstream generator option will determine
whether the unused I/Os have a pull-up, pull-down, or no resistor.
•
•
Loading data frames
Start-up
Signals
There are two kinds of pins that are used to configure
Spartan-IIE devices: Dedicated pins perform only specific
configuration-related functions; the other pins can serve as
general purpose I/Os once user operation has begun.
The memory clearing and start-up phases are the same for
all configuration modes; however, the steps for the loading
of data frames are different. Thus, the details for data frame
loading are described separately in the sections devoted to
each mode.
The dedicated pins comprise the mode pins (M2, M1, M0),
the configuration clock pin (CCLK), the PROGRAM pin, the
DONE pin and the boundary-scan pins (TDI, TDO, TMS,
TCK). Depending on the selected configuration mode,
CCLK may be an output generated by the FPGA, or may be
generated externally, and provided to the FPGA as an input.
Initiating Configuration
There are two different ways to initiate the configuration pro-
cess: applying power to the device or asserting the PRO-
GRAM input.
Note that some configuration pins can act as outputs. For
correct operation, these pins require a VCCO of 3.3V to drive
an LVTTL signal or 2.5V to drive an LVCMOS signal. All the
relevant pins fall in banks 2 or 3. The CS and WRITE pins
for Slave Parallel mode are located in bank 1.
Configuration on power-up occurs automatically unless it is
delayed by the user, as described in a separate section
below. The waveform for configuration on power-up is
shown in Configuration Switching Characteristics, page 48.
Before configuration can begin, VCCO Bank 2 must be
greater than 1.0V. Furthermore, all VCCINT power pins must
be connected to a 1.8V supply. For more information on
delaying configuration, see Clearing Configuration Memory,
page 23.
For a more detailed description than that given below, see
Module 1 and XAPP176, Configuration and Readback of
the Spartan-II and Spartan-IIE FPGA Families.
The Process
The sequence of steps necessary to configure Spartan-IIE
devices are shown in Figure 16. The overall flow can be
divided into three different phases.
Once in user operation, the device can be re-configured
simply by pulling the PROGRAM pin Low. The device
acknowledges the beginning of the configuration process by
driving DONE Low, then enters the memory-clearing phase.
•
•
Initiating configuration
Configuration memory clear
22
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DS077-2 (v2.3) June 18, 2008
Product Specification
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