
Altera Corporation
9–3
January 2008
Stratix II Device Handbook, Volume 2
IEEE 1149.1 (JTAG) Boundary-Scan Testing for Stratix II and Stratix II GX Devices
Table 9–1 summarizes the functions of each of these pins.
The IEEE Std. 1149.1 BST circuitry requires the following registers:
■
The instruction register determines the action to be performed and
the data register to be accessed.
■
The bypass register is a 1-bit-long data register that provides a
minimum-length serial path between TDI and TDO.
■
The boundary-scan register is a shift register composed of all the
boundary-scan cells of the device.
Table 9–1. IEEE Std. 1149.1 Pin Descriptions
Pin
Description
Function
TDI
Test data input
Serial input pin for instructions as well as test and programming data.
Data is shifted in on the rising edge of TCK.
TDO
Test data output
Serial data output pin for instructions as well as test and programming
data. Data is shifted out on the falling edge of TCK. The pin is tri-stated
if data is not being shifted out of the device.
TMS
Test mode select
Input pin that provides the control signal to determine the transitions of
the Test Access Port (TAP) controller state machine. Transitions within
the state machine occur at the rising edge of TCK. Therefore, TMS
must be set up before the rising edge of TCK. TMS is evaluated on the
rising edge of TCK.
TCK
Test clock input
The clock input to the BST circuitry. Some operations occur at the
rising edge, while others occur at the falling edge.
TRST
Test reset input
(optional)
Active-low input to asynchronously reset the boundary-scan circuit.
This pin should be driven low when not in boundary-scan operation
and for non-JTAG users the pin should be permanently tied to GND.