XC18V00 Series In-System Programmable Configuration PROMs
8 www.xilinx.com DS026 (v3.9) November 18, 2002
1-800-255-7778 Product Specification
R
Boundary Scan Register
The boundary-scan register is used to control and observe
the state of the device pins during the EXTEST, SAM-
PLE/PRELOAD, and CLAMP instructions. Each output pin
on the XC18V00 has two register stages that contribute to
the boundary-scan register, while each input pin only has
one register stage.
For each output pin, the register stage nearest to TDI con-
trols and observes the output state, and the second stage
closest to TDO controls and observes the High-Z enable
state of the pin.
For each input pin, the register stage controls and observes
the input state of the pin.
Identification Registers
The IDCODE is a fixed, vendor-assigned value that is used
to electrically identify the manufacturer and type of the
device being addressed. The IDCODE register is 32 bits
wide. The IDCODE register can be shifted out for examina-
tion by using the IDCODE instruction. The IDCODE is avail-
able to any other system component via JTAG.
The IDCODE register has the following binary format:
vvvv:ffff:ffff:aaaa:aaaa:cccc:cccc:ccc1
where
v = the die version number
f = the family code (50h for XC18V00 family)
a = the ISP PROM product ID (26h for the XC18V04)
c = the company code (49h for Xilinx)
Note: The LSB of the IDCODE register is always read as
logic “1” as defined by IEEE Std. 1149.1.
Table 5 lists the IDCODE register values for the XC18V00
devices.
The USERCODE instruction gives access to a 32-bit user
programmable scratch pad typically used to supply informa-
tion about the device’s programmed contents. By using the
USERCODE instruction, a user-programmable identifica-
tion code can be shifted out for examination. This code is
loaded into the USERCODE register during programming of
the XC18V00 device. If the device is blank or was not
loaded during programming, the USERCODE register con-
tains FFFFFFFFh.
XC18V00 TAP Characteristics
The XC18V00 family performs both in-system programming
and IEEE 1149.1 boundary-scan (JTAG) testing via a single
4-wire Test Access Port (TAP). This simplifies system
designs and allows standard Automatic Test Equipment to
perform both functions. The AC characteristics of the
XC18V00 TAP are described as follows.
TAP Timing
Figure 4 shows the timing relationships of the TAP signals.
These TAP timing characteristics are identical for both
boundary-scan and ISP operations.
IR[7:5] IR[4] IR[3] IR[2] IR[1:0]
TDI-> 0 0 0 ISP
Status
Security 0 0 1
->TDO
Notes:
1. IR(1:0) = 01 is specified by IEEE Std. 1149.1
Figure 3: Instruction Register Values Loaded into IR as
Part of an Instruction Scan Sequence
Table 5 : IDCODES Assigned to XC18V00 Devices
ISP-PROM IDCODE
XC18V01 05024093h
XC18V02 05025093h
XC18V04 05026093h
XC18V256 05022093h
XC18V512 05023093h
