Spartan-3E FPGA Family: Functional Description
DS312 (v4.1) July 19, 2013
Product Specification
101
Voltage Compatibility
The 2.5V VCCAUX supply powers the JTAG interface. All of
the user I/Os are separately powered by their respective
VCCO_# supplies.
When connecting the Spartan-3E JTAG port to a 3.3V
interface, the JTAG input pins must be current-limited to
10 mA or less using series resistors. Similarly, the TDO pin
is a CMOS output powered from +2.5V. The TDO output can
directly drive a 3.3V input but with reduced noise immunity.
See
XAPP453: The 3.3V Configuration of Spartan-3
FPGAs for additional information.
JTAG Device ID
Each Spartan-3E FPGA array type has a 32-bit
device-specific JTAG device identifier as shown in
Table 67.
The lower 28 bits represent the device vendor (Xilinx) and
device identifer. The upper four bits, ignored by most tools,
represent the revision level of the silicon mounted on the
printed circuit board.
Table 67 associates the revision code
with a specific stepping level.
JTAG User ID
The Spartan-3E JTAG interface also provides the option to
store a 32-bit User ID, loaded during configuration. The
User ID value is specified via the UserID configuration
Using JTAG Interface to Communicate to a
Configured FPGA Design
After the FPGA is configured, using any of the available
modes, the JTAG interface offers a possible
communications channel to internal FPGA logic. The
BSCAN_SPARTAN3 design primitive provides two private
JTAG instructions to create an internal boundary scan
chain.
X-Ref Target - Figure 65
Figure 65: JTAG Configuration Mode
TDI
TDO
TMS
TCK
VCCINT
VCCAUX
+2.5V
VCCO_2
PROG_B
DONE
GND
+1.2V
HSWAP
VCCO_0
P
VCCO_0
Spartan-3E
FPGA
+2.5V
JTAG
TCK
TMS
Spartan-3E
FPGA
TDI
TMS
TCK
TDO
M2
M1
‘1’
‘0’
M0
‘1’
JTAG
Mode
VCCO_2
TDI
TDO
TMS
TCK
VCCINT
VCCAUX
+2.5V
VCCO_2
PROG_B
DONE
GND
+1.2V
HSWAP
VCCO_0
P
VCCO_0
M2
M1
‘1’
‘0’
M0
‘1’
JTAG
Mode
VCCO_2
DS312-2_56_082009
Table 67: Spartan-3E JTAG Device Identifiers
Spartan-3E
FPGA
4-Bit Revision Code
28-Bit
Vendor/Device
Identifier
Step 0
Step 1
XC3S100E
0x0
0x1
0x1C 10 093
XC3S250E
0x0
0x1
0x1C 1A 093
XC3S500E
0x0
0x2
0x4
0x1C 22 093
XC3S1200E
0x0
0x1
0x2
0x1C 2E 093
XC3S1600E
0x0
0x1
0x2
0x1C 3A 093