40MX and 42MX FPGA Families
parallel ports are connected to the internal core logic tile and the input, output and control ports of an I/O
buffer to capture and load data into the register to control or observe the logic state of each I/O.
Boundary Scan Register
Figure 1-13 • 42MX IEEE 1149.1 Boundary Scan Circuitry
Table 1-3 • Test Access Port Descriptions
(Test Mode Select)
Serial input for the test logic control bits. Data is captured on the rising edge of the test logic
(Test Clock Input)
Dedicated test logic clock used serially to shift test instruction, test data, and control inputs
on the rising edge of the clock, and serially to shift the output data on the falling edge of the
clock. The maximum clock frequency for TCK is 20 MHz.
(Test Data Input)
Serial input for instruction and test data. Data is captured on the rising edge of the test logic
(Test Data Output)
Serial output for test instruction and data from the test logic. TDO is set to an Inactive Drive
state (high impedance) when data scanning is not in progress.
Table 1-4 • Supported BST Public Instructions
IR Code Instruction
000 Mandatory Allows the external circuitry and board-level interconnections to be
tested by forcing a test pattern at the output pins and capturing test
results at the input pins.
SAMPLE/PRELOAD 001 Mandatory Allows a snapshot of the signals at the device pins to be captured
and examined during operation
Optional Tristates all I/Os to allow external signals to drive pins. Please refer to
the IEEE Standard 1149.1 specification.
Optional Allows state of signals driven from component pins to be determined
from the Boundary-Scan Register. Please refer to the IEEE Standard
1149.1 specification for details.
111 Mandatory Enables the bypass register between the TDI and TDO pins. The test
data passes through the selected device to adjacent devices in the