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ULINK: CONNECTION ISSUES WITH INFINEON XE16X/XC2XXX DEVICES


Information in this article applies to:

  • ULINK USB-JTAG Adapter

QUESTION

I am having trouble using an Infineon XE16x/XC2xxx device with Keil ULINK USB-JTAG Adapter. Whenever I try to start a flash download or a debug session, I get the error message:

No JTAG device found

Infineon XC16x devices work as expected with the same ULINK. Are XE16x/XC2xxx devices not supported by ULINK?

ANSWER

Compared to Infineon XC16x devices, XE16x/XC2xxx devices have a much stronger on-chip pull-down resistor at JTAG pin TRST. In normal operation, this pin should be sampled 'low' during a reset to disable debug features. With ULINK connected, this pin must be 'high'. ULINK generates the TRST signal with an open collector output that has an 10K pull-up resistor. This pull-up resistor is not strong enough to generate a reliable 'high' level.

This problem report does not apply to the ULINK2 adapter because it has different JTAG line drivers.

Please note that Infineon XC2xxx devices are supported with PK166 version 6.08 and later.

RESOLUTION

There are several ways to fix that problem:

  • Use ULINK2 instead of ULINK.
  • Connect an additional 10K pull-up resistor to TRST ( pin 9 on JTAG connector) on your target board while debugging or flash programming with ULINK.
  • Replace the 10K pull-up resistor (R13) in ULINK with a 4.7K resistor. R13 is close to IC2 and T2. Please see the JTAG Interface Schematics for more details. ULINK will still be compatible with other devices.

SEE ALSO

Last Reviewed: Wednesday, July 30, 2008


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