8. JTAG Boundary-Scan Testing in MAX V
Devices
December 2010
MV51008-1.0
MV51008-1.0
This chapter describes the IEEE Std.1149.1 (JTAG) boundary-scan testing for Altera®
MAX® V devices. The IEEE Std. 1149.1 BST circuitry available in MAX V devices
provides a cost-effective and efficient way to test systems that contain devices with
tight lead spacing. Circuit boards with Altera and other IEEE Std. 1149.1-compliant
devices can use EXTEST, SAMPLE/PRELOAD, and BYPASSmodes to create serial patterns
that internally test the pin connections between devices and check device operation.
As PCBs become more complex, the requirement for thorough testing becomes
increasingly important. Advances in surface-mount packaging and PCB
manufacturing have resulted in smaller boards, making traditional test methods (for
example, external test probes and “bed-of-nails” test fixtures) harder to implement.
As a result, cost savings from PCB space reductions are sometimes offset by cost
increases in traditional testing methods.
In the 1980s, JTAG developed a specification for boundary-scan testing that was later
standardized as the IEEE Std. 1149.1 specification. This boundary-scan test (BST)
architecture offers the capability to efficiently test components on PCBs with tight
lead spacing.
BST architecture can test pin connections without using physical test probes and
capture functional data while a device is operating normally. Boundary-scan cells
(BSCs) in a device can force signals onto pins, or capture data from pin or core logic
signals. Forced test data is serially shifted into the BSCs. Captured data is serially
shifted out and externally compared to expected results.
Figure 8–1 shows the concept of boundary-scan testing.
Figure 8–1. IEEE Std. 1149.1 Boundary-Scan Testing
Boundary-Scan Cell
Serial
Data In
Serial
Data Out
IC Pin Signal
Core
Logic
Core
Logic
Interconnection
to Be Tested
JTAG Device 1
JTAG Device 2
This chapter describes the following topics:
■
■
■
■
■
“IEEE Std. 1149.1 BST Architecture” on page 8–2
“IEEE Std. 1149.1 Boundary-Scan Register” on page 8–3
“IEEE Std. 1149.1 BST Operation Control” on page 8–6
“I/O Voltage Support in the JTAG Chain” on page 8–13
“Boundary-Scan Test for Programmed Devices” on page 8–14
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MAX V Device Handbook
December 2010
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