11–8
Chapter 11: In-System Programmability Guidelines for MAX II Devices
ISP Troubleshooting Guidelines
TDO Is Not Connected
You will receive an error if the
TDO
port of one device in the chain is not connected.
During in-system programming, data must be shifted in and out of each device in the
JTAG chain through the JTAG pins. Therefore, each device’s
TDO
port must be
connected to the subsequent device’s
TDI
port, and the last device’s
TDO
port must be
connected to the download cable’s
TDO
port.
Incomplete JTAG Chain
You will receive an error if the JTAG chain is not complete. To check if an incomplete
JTAG chain is causing the error, use an oscilloscope to monitor vectors coming out of
each device in the chain. If each device’s
TDO
port does not toggle during in-system
programming, your JTAG chain is not complete.
Noisy TCK Signal
Noise on the
TCK
signal is the most common reason for in-system programming
errors. Noisy transitions on rising or falling edges can cause incorrect clocking of the
IEEE Std. 1149.1 TAP controller, causing the state machine to be lost and in-system
programming to fail. For more information about dealing with noisy
TCK
signals,
refer to
Jam Player Ported Incorrectly
You will receive an error if the Jam Player was not ported correctly for your platform.
To check if the Jam Player is causing the error, apply the
IDCODE
instruction to the
target device using a Jam file. You can use a Jam file to load an
IDCODE
instruction
and then shift out the
IDCODE
value. This test determines if the JTAG chain is set up
correctly and if you can read and write to the JTAG chain properly.
You can download the
idcode.zip
file from the Altera website to obtain the
idcode.jam
file.
Troubleshooting Tips
This section discusses some additional suggestions for troubleshooting ISP issues.
Verify the JTAG Chain Continuity
For in-system programming to occur successfully, the number of devices physically in
the JTAG chain must match the number reported in the Quartus II software. The
following steps show one simple way to verify that the JTAG chain is connected
properly.
1. Open the Programmer in the Quartus II software.
2. Click
Auto Detect
in the Programmer. The Quartus II software reports the number
of devices found on the JTAG chain. If this fails, check the JTAG chain to make sure
it is not broken.
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