Chapter 15: Using the Agilent 3070 Tester for In-System Programming
15–3
Agilent 3070 Development Flow without the PLD ISP Software
Step 1: Create a PCB and Test Fixture
Before starting test development, the first step to successful in-system programming
is the proper layout of the board and the subsequent creation of the test fixture.
Creating the PCB
The following recommendations highlight important areas of PCB design issues:
■
The TCKsignal trace should be treated as carefully as a clock tree. TCKis the clock
for the entire Joint Test Action Group (JTAG) chain of devices. These devices are
edge-triggered on the TCKsignal, so it is imperative that this signal be protected
from high-frequency noise and have good signal integrity. Ensure that the signal
meets the tR and tF parameters specified in the device data sheet.
■
Add a pull-down resistor to TCK. The TCKsignal should be held low through a
pull-down resistor in-between PCF downloads. For more information about
pattern capture format (PCF) downloads, refer to “Step 2: Create a Serial Vector
Format File”. You should hold TCKlow because the Agilent 3070 drivers go into a
“high-Z” state in-between tests and briefly drive low as the next PCF is applied.
When the TCKline “floats”, the programming data stream is corrupted and the
device is not programmed correctly.
■
Provide VCCand GNDtest access points for the nails of the test fixture. During
operation, there should be enough access points to allow quiet PCB operation.
Having too few access points results in a noisy system that can disrupt JTAG
scans.
■
■
Turn off on-board oscillators. During programming, on-board oscillators should
have the ability to be electrically turned off to reduce system noise.
Add external resistors to pull outputs to a defined logic level during
programming.
1
Output pins are tri-stated during programming and are pulled up by a weak internal
resistor. However, Altera recommends that signals requiring a pre-defined level be
externally forced to the appropriate level using an external resistor.
f
For more information about board design for ISP, refer to the In-System
Programmability Guidelines for MAX II Devices chapter in the MAX II Device Handbook.
Creating the Fixture
Providing a clean interface between the test fixture and the target board is essential for
successful in-system programming. To provide a clean interface, use short wires in the
test fixture to improve the TCKconnection. Longer wires can introduce inductive
noise into the system, which can disrupt programming. The wire connecting TCK
should be no longer than 1 inch. Use the Agilent Fixture Consultant to manage the
layout and creation of the test fixture (see the Agilent Board Test Family Manual).
© October 2008 Altera Corporation
MAX II Device Handbook
ALTERA [ ALTERA CORPORATION ]
