R
Functional Description
+1.2V
V
VCCINT
HSWAP
VCCO_0
VCCO_0
P
I
VCCO
VCCO_1
LDC0
V
CE#
x8 or
x8/x16
Flash
LDC1
OE#
HDC
WE#
BYTE#
PROM
LDC2
Not available
in VQ100
package
D
A[16:0]
DQ[15:7]
BPI Mode
VCCO_2
D[7:0]
V
‘0’
‘1’
A
M2
M1
M0
DQ[7:0]
A[n:0]
A[23:17]
GND
V
Spartan-3E
FPGA
BUSY
CCLK
‘0’
‘0’
CSI_B
CSO_B
INIT_B
RDWR_B
+2.5V
JTAG
+2.5V
VCCAUX
TDO
+2.5V
TDI
TDI
TMS
TCK
TDO
TMS
TCK
PROG_B
DONE
GND
PROG_B
Recommend
open-drain
driver
DS312-2_49_022305
Figure 55: Byte-wide Peripheral Interface (BPI) Mode Configured from Parallel NOR Flash PROMs
A
During configuration, the value of the M0 mode pin
Depending on the specific processor architecture, the pro-
cessor boots either from the top or bottom of memory. The
FPGA is flexible and boots from the opposite end of mem-
ory from the processor. Only the processor or the FPGA can
boot at any given time. The FPGA can configure first, hold-
ing the processor in reset or the processor can boot first,
asserting the FPGA’s PROG_B pin.
determines how the FPGA generates addresses, as shown
Table 50. When M0 = 0, the FPGA generates addresses
starting at 0 and increments the address on every falling
CCLK edge. Conversely, when M0 = 1, the FPGA gener-
ates addresses starting at 0xFF_FFFF (all ones) and decre-
ments the address on every falling CCLK edge.
The mode select pins, M[2:0], are sampled when the
FPGA’s INIT_B output goes High and must be at defined
logic levels during this time. After configuration, when the
FPGA’s DONE output goes High, the mode pins are avail-
able as full-featured user-I/O pins.
Table 50: BPI Addressing Control
M2
M1
M0 Start Address
Addressing
Incrementing
Decrementing
0
1
0
0
1
Similarly, the FPGA’s HSWAP pin must be Low to
P
0xFF_FFFF
enable pull-up resistors on all user-I/O pins or High to dis-
able the pull-up resistors. The HSWAP control must remain
at a constant logic level throughout FPGA configuration.
After configuration, when the FPGA’s DONE output goes
This addressing flexibility allows the FPGA to share the par-
allel Flash PROM with an external or embedded processor.
72
www.xilinx.com
DS312-2 (v1.1) March 21, 2005
Advance Product Specification
XILINX [ XILINX, INC ]
